Servlet 详细教程 + 案例

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Servlet 详细教程 + 案例

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Servlet 方法介绍

  • init():初始化方法
    • 调用时机:默认情况下,servlet 被第一次访问时,调用
      • 可通过 loadOnStartup 修改
    • 调用次数:1次
  • service():提供服务
    • 调用时机:每一次Servlet被访问时,调用
    • 调用次数:多次
  • destory():销毁方法
    • 调用时机:内存释放或者服务器关闭的时候,Servlet对象会被销毁,调用
    • 调用次数:1次
  • getServletConfig():获取 ServletConfig 对象
  • getServletInfo():获取 Servlet 信息(author、version、copyright)

Servlet urlPattern 配置

  • 一个 Servlet 可以配置多个 urlPattern @WebServlet(urlPatterns = {"/demo3", "/demo4"})
  • urlPattern 配置规则
    • 精确匹配
      • 配置路径:@WebServlet("/demo3")
      • 访问路径:localhost:8080/web-demo/demo3
    • 目录匹配
      • 配置路径:@WebServlet("/user/*")
      • 访问路径:localhost:8080/web-demo/user/aaalocalhost:8080/web-demo/user/bbb
    • 扩展名匹配
      • 配置路径:@WebServlet("*.do")
      • 访问路径:localhost:8080/web-demo/aaa.dolocalhost:8080/web-demo/bbb.do
    • 任意匹配
      • 配置路径:@WebServlet("/")@WebServlet("/*")
      • 访问路径:localhost:8080/web-demo/hehelocalhost:8080/web-demo/haha

//* 的区别

  • 当我们的项目中的Servlet配置了 /,会覆盖掉 tomcat 中的 DefaultServlet,当其他的 url-pattern 都匹配不上时都会走这个Servlet
  • 当我们的项目中配置了 /*,意味着匹配任意访问路径

优先级:精确路径 > 目录路径 > 扩展名路径 > /* > /

IDEA 模板创建 Servlet

#if (${PACKAGE_NAME} && ${PACKAGE_NAME} != "")package ${PACKAGE_NAME};#end
#parse("File Header.java")

#if ($JAVAEE_TYPE == "jakarta")
import jakarta.servlet.*;
import jakarta.servlet.http.*;
import jakarta.servlet.annotation.*;
#else
import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
#end
import java.io.IOException;

@WebServlet("/${Entity_Name}")
public class ${Class_Name} extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }
}
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中文乱码问题

POST 乱码

  • getReader() 默认编码是 iso-8859-1
  • 设置字符输入流的编码为 UTF-8request.setCharacterEncoding("UTF-8");

GET 乱码

在这里插入图片描述

  • URL 编码

    • 将字符串按照编码方式转为二进制
    • 每个字节转为2个16进制并在前边加上% 在这里插入图片描述
  • URL编解码Demo

    package com.ruochen.web;
    
    import java.io.UnsupportedEncodingException;
    import java.net.URLDecoder;
    import java.net.URLEncoder;
    
    public class URLDemo {
        public static void main(String[] args) throws UnsupportedEncodingException {
            String username = "张三";
    
            // 1. URL 编码
            String encode = URLEncoder.encode(username, "utf-8");
            System.out.println(encode);
    
            // 2. URL 解码
            String decode = URLDecoder.decode(encode, "ISO-8859-1");
            System.out.println(decode);
        }
    }
    复制代码
      %E5%BC%A0%E4%B8%89
      å¼ ä¸‰
    复制代码
  • tomcat ISO-8859-1 接码我们无法改变,但是我们可以发现 URL 编码数据和接收打的数据字节是一样的(二进制数据 10101xxxx),这就为我们提供了一种思路:我们可以将乱码的数据转换为字节数据(二进制数据),再将二进制字节数据转换为字符串,demo 如下

    package com.ruochen.web;
    
    import java.io.UnsupportedEncodingException;
    import java.net.URLDecoder;
    import java.net.URLEncoder;
    
    public class URLDemo {
        public static void main(String[] args) throws UnsupportedEncodingException {
            String username = "张三";
    
            // 1. URL 编码
            String encode = URLEncoder.encode(username, "utf-8");
            System.out.println(encode);
    
            // 2. URL 解码
            String decode = URLDecoder.decode(encode, "ISO-8859-1");
            System.out.println(decode);
    
            // 3. 转换为字节数据,编码
            byte[] bytes = decode.getBytes("ISO-8859-1");
            for (byte b : bytes) {
                System.out.print(b + " ");
            }
            System.out.println();
    
            // 4. 将字节数组转换为字符串,解码
            String string = new String(bytes, "utf-8");
            System.out.println(string);
        }
    }
    复制代码
      %E5%BC%A0%E4%B8%89
      å¼ ä¸‰
      -27 -68 -96 -28 -72 -119 
      张三
    复制代码
  • servlet demo

    @WebServlet("/req1")
    public class RequestDemo1 extends HttpServlet {
        @Override
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            // 解决post乱码 getReader() 默认编码是 iso-8859-1
            request.setCharacterEncoding("UTF-8");  // 设置字符输入流的编码
    
            String username = request.getParameter("username");
            System.out.println("解决乱码前:" + username);
    
            // GET 获取参数的方式:getQueryString()
            // 乱码原因:tomcat 进行URL解码,默认的字符集ISO-8859-1
            // 1. 先对乱码进行编码,转为字节数组
            // byte[] bytes = username.getBytes(StandardCharsets.ISO_8859_1);
            // 2. 字节数组解码
            // username = new String(bytes, StandardCharsets.UTF_8);
            username = new String(username.getBytes(StandardCharsets.ISO_8859_1), StandardCharsets.UTF_8);
    
            System.out.println("解决乱码后:" + username);
        }
    
        @Override
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            this.doGet(request, response);
        }
    }
    复制代码

Tomcat 8 之后,已将GET请求乱码问题解决,设置默认的解码方式为 UTF-8

路径问题

  • 明确路径谁使用?
    • 浏览器使用:需要加虚拟目录(项目访问路径)
    • 服务端使用:不需要加虚拟目录
  • 练习
    • <a href = "路径">:加虚拟目录
    • <form action="路径">:加虚拟目录
    • req.getRequestDispatcher("路径"):不需要加虚拟目录
    • resp.sendRedirect("路径"):需要加虚拟目录

Response 响应字符数据

  • 使用 Response 对象获取字符输出流:PrintWriter writer = resp.getWriter();
  • 写数据:write.write("aaa");
  • 可通过设置 header 指定类型:resp.setHeader("content-type", "text/html");
  • 流不需要关闭,resp 对象销毁的时候会自动关闭
  • 中文乱码,设置流的编码:resp.setContentType("text/html;charset=utf-8");

Response 响应字节数据

  • 通过 Response 对象获取字节输出流:ServletOutputStream outputStream = resp.getOutputStream();
  • 写数据:outputStream.write(字节数据);
  • 案例
    package com.ruochen.web;
    
    import javax.servlet.*;
    import javax.servlet.http.*;
    import javax.servlet.annotation.*;
    import java.io.FileInputStream;
    import java.io.IOException;
    
    @WebServlet("/resp1")
    public class ResponseDemo1 extends HttpServlet {
        @Override
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    
            // 1. 读取文件
            FileInputStream fis = new FileInputStream("C:\\Users\\ruochen\\Desktop\\离雨.jpg");
    
            // 2. 获取 response 字节输出流
            ServletOutputStream os = response.getOutputStream();
    
            // 3. 完成流的 copy
            byte[] buff = new byte[1024];
            int len = 0;
            while((len = fis.read(buff)) != -1) {
                os.write(buff, 0, len);
            }
            fis.close();
        }
    
        @Override
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            this.doGet(request, response);
        }
    }
    复制代码
  • 我们可以使用 commons-io 工具类简化上述操作
  • 导入坐标:pom.xml
            <dependency>
                <groupId>commons-io</groupId>
                <artifactId>commons-io</artifactId>
                <version>2.6</version>
            </dependency>
    复制代码
  • 上述循环遍历代码可简化为如下
    IOUtils.copy(fis, os);
    复制代码

用户登录案例

准备工作

  • login.html 放到 webapp 目录下
    <!DOCTYPE html>
    <html lang="en">
    
    <head>
        <meta charset="UTF-8">
        <title>login</title>
        <link href="css/login.css" rel="stylesheet">
    </head>
    
    <body>
    <div id="loginDiv">
        <form action="/web-demo/loginServlet" method="post" id="form">
            <h1 id="loginMsg">LOGIN IN</h1>
            <p>Username:<input id="username" name="username" type="text"></p>
    
            <p>Password:<input id="password" name="password" type="password"></p>
    
            <div id="subDiv">
                <input type="submit" class="button" value="login up">
                <input type="reset" class="button" value="reset">&nbsp;&nbsp;&nbsp;
                <a href="register.html">没有账号?点击注册</a>
            </div>
        </form>
    </div>
    
    </body>
    </html>
    复制代码
  • login.css
    * {
        margin: 0;
        padding: 0;
    }
    
    html {
        height: 100%;
        width: 100%;
        overflow: hidden;
        margin: 0;
        padding: 0;
        background: url(../imgs/Desert.jpg) no-repeat 0px 0px;
        background-repeat: no-repeat;
        background-size: 100% 100%;
        -moz-background-size: 100% 100%;
    }
    
    body {
        display: flex;
        align-items: center;
        justify-content: center;
        height: 100%;
    }
    
    #loginDiv {
        width: 37%;
        display: flex;
        justify-content: center;
        align-items: center;
        height: 300px;
        background-color: rgba(75, 81, 95, 0.3);
        box-shadow: 7px 7px 17px rgba(52, 56, 66, 0.5);
        border-radius: 5px;
    }
    
    #name_trip {
        margin-left: 50px;
        color: red;
    }
    
    p {
        margin-top: 30px;
        margin-left: 20px;
        color: azure;
    }
    
    input {
        margin-left: 15px;
        border-radius: 5px;
        border-style: hidden;
        height: 30px;
        width: 140px;
        background-color: rgba(216, 191, 216, 0.5);
        outline: none;
        color: #f0edf3;
        padding-left: 10px;
    }
    #username{
        width: 200px;
    }
    #password{
        width: 202px;
    }
    .button {
        border-color: cornsilk;
        background-color: rgba(100, 149, 237, .7);
        color: aliceblue;
        border-style: hidden;
        border-radius: 5px;
        width: 100px;
        height: 31px;
        font-size: 16px;
    }
    
    #subDiv {
        text-align: center;
        margin-top: 30px;
    }
    #loginMsg{
        text-align: center;color: aliceblue;
    }
    复制代码
  • 创建 db1 数据库,创建 tb_user 表,创建 User 实体类
    -- 创建数据库
    create database db1 character set utf8;
    use db1;
    
    -- 创建用户表
    CREATE TABLE tb_user(
    	id int primary key auto_increment,
    	username varchar(20) unique,
    	password varchar(32)
    );
    
    -- 添加数据
    INSERT INTO tb_user(username,password) values('zhangsan','123'),('lisi','234');
    
    SELECT * FROM tb_user;
    复制代码
    package com.ruochen.pojo;
    
    public class User {
    
        private Integer id;
        private String username;
        private String password;
    
        public Integer getId() {
            return id;
        }
    
        public void setId(Integer id) {
            this.id = id;
        }
    
        public String getUsername() {
            return username;
        }
    
        public void setUsername(String username) {
            this.username = username;
        }
    
        public String getPassword() {
            return password;
        }
    
        public void setPassword(String password) {
            this.password = password;
        }
    
        @Override
        public String toString() {
            return "User{" +
                    "id=" + id +
                    ", username='" + username + '\'' +
                    ", password='" + password + '\'' +
                    '}';
        }
    }
    复制代码
  • 导入MyBatis 坐标,MySQL 驱动坐标
            <dependency>
                <groupId>org.mybatis</groupId>
                <artifactId>mybatis</artifactId>
                <version>3.5.5</version>
            </dependency>
    
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <version>5.1.34</version>
            </dependency>
    复制代码
  • 创建 mybatis-config.xml 核心配置文件,UserMapper.xml 映射文件,UserMapper 接口
    • mybatis-config.xml
    <?xml version="1.0" encoding="UTF-8" ?>
    <!DOCTYPE configuration
            PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
            "http://mybatis.org/dtd/mybatis-3-config.dtd">
    <configuration>
        <!--起别名-->
        <typeAliases>
            <package name="com.ruochen.pojo"/>
        </typeAliases>
    
        <environments default="development">
            <environment id="development">
                <transactionManager type="JDBC"/>
                <dataSource type="POOLED">
                    <property name="driver" value="com.mysql.jdbc.Driver"/>
                    <property name="url" value="jdbc:mysql:///db1?useSSL=false&amp;useServerPrepStmts=true"/>
                    <property name="username" value="root"/>
                    <property name="password" value="ruochen666"/>
                </dataSource>
            </environment>
        </environments>
        <mappers>
            <!--扫描mapper-->
            <package name="com.ruochen.mapper"/>
        </mappers>
    </configuration>
    复制代码
    • UserMapper.xml
    <?xml version="1.0" encoding="UTF-8" ?>
    <!DOCTYPE mapper
            PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
            "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
    <mapper namespace="com.ruochen.mapper.UserMapper">
    
    </mapper>
    复制代码
    • UserMapper.java
    package com.ruochen.mapper;
    
    public interface UserMapper {
    
    }
    复制代码
  • 目录树如下

流程

  • UserMapper.java
    package com.ruochen.mapper;
    
    import com.ruochen.pojo.User;
    import org.apache.ibatis.annotations.Param;
    import org.apache.ibatis.annotations.Select;
    
    public interface UserMapper {
    
        /**
         * 根据用户名和密码查询用户对象
         * @param username
         * @param password
         * @return
         */
        @Select("select * from tb_user where username= #{username} and password = #{password}")
        User select(@Param("username") String username, @Param("password") String password);
    }
    复制代码
  • UserServlet.java
    package com.ruochen.web;
    
    import com.ruochen.mapper.UserMapper;
    import com.ruochen.pojo.User;
    import org.apache.ibatis.io.Resources;
    import org.apache.ibatis.session.SqlSession;
    import org.apache.ibatis.session.SqlSessionFactory;
    import org.apache.ibatis.session.SqlSessionFactoryBuilder;
    
    import javax.servlet.*;
    import javax.servlet.http.*;
    import javax.servlet.annotation.*;
    import java.io.IOException;
    import java.io.InputStream;
    import java.io.PrintWriter;
    
    @WebServlet("/loginServlet")
    public class LoginServlet extends HttpServlet {
        @Override
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            // 1. 接收用户名和密码
            String username = request.getParameter("username");
            String password = request.getParameter("password");
    
            // 2. 调用 MyBatis 完成查询
            // 2.1 获取 SqlSessionFactory 对象
            String resource = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
            // 2.2 获取 SqlSession 对象
            SqlSession sqlSession = sqlSessionFactory.openSession();
            // 2.3 获取 Mapper
            UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
            // 2.4 调用方法
            User user = userMapper.select(username, password);
            // 2.5 释放资源
            sqlSession.close();
    
            // 获取字符输出流,并设置 content-type
            response.setContentType("text/html;charset=utf-8");
            PrintWriter writer = response.getWriter();
            // 3. 判断 User 是否为 null
            if (user != null) {
                // 登录成功
                writer.write("登录成功");
            } else {
                // 登录失败
                writer.write("登录失败");
            }
        }
    
        @Override
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            this.doGet(request, response);
        }
    }
    复制代码

用户注册案例

  • register.html
    <!DOCTYPE html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>欢迎注册</title>
        <link href="css/register.css" rel="stylesheet">
    </head>
    <body>
    
    <div class="form-div">
        <div class="reg-content">
            <h1>欢迎注册</h1>
            <span>已有帐号?</span> <a href="login.html">登录</a>
        </div>
        <form id="reg-form" action="#" method="get">
    
            <table>
    
                <tr>
                    <td>用户名</td>
                    <td class="inputs">
                        <input name="username" type="text" id="username">
                        <br>
                        <span id="username_err" class="err_msg" style="display: none">用户名不太受欢迎</span>
                    </td>
    
                </tr>
    
                <tr>
                    <td>密码</td>
                    <td class="inputs">
                        <input name="password" type="password" id="password">
                        <br>
                        <span id="password_err" class="err_msg" style="display: none">密码格式有误</span>
                    </td>
                </tr>
    
    
            </table>
    
            <div class="buttons">
                <input value="注 册" type="submit" id="reg_btn">
            </div>
            <br class="clear">
        </form>
    
    </div>
    </body>
    </html>
    复制代码
  • UserMapper.java
        /**
         * 根据用户名查询用户对象
         * @param username
         * @return
         */
        @Select("select * from tb_user where username = #{username}")
        User selectByUserName(String username);
    
        /**
         * 添加用户
         * @param user
         */
        @Insert("insert into tb_user values (null, #{username}, #{password});")
        void add(User user);
    复制代码
  • RegisterServlet
    package com.ruochen.web;
    
    import com.ruochen.mapper.UserMapper;
    import com.ruochen.pojo.User;
    import org.apache.ibatis.io.Resources;
    import org.apache.ibatis.session.SqlSession;
    import org.apache.ibatis.session.SqlSessionFactory;
    import org.apache.ibatis.session.SqlSessionFactoryBuilder;
    
    import javax.servlet.*;
    import javax.servlet.http.*;
    import javax.servlet.annotation.*;
    import java.io.IOException;
    import java.io.InputStream;
    
    @WebServlet("/registerServlet")
    public class RegisterServlet extends HttpServlet {
        @Override
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            // 1. 接收用户数据
            String username = request.getParameter("username");
            String password = request.getParameter("password");
    
            // 封装用户对象
            User user = new User();
            user.setUsername(username);
            user.setPassword(password);
    
            // 2. 调用 Mapper 根据用户名查询用户对象
            // 2.1 获取 SqlSessionFactory 对象
            String resource = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
            // 2.2 获取 SqlSession 对象
            SqlSession sqlSession = sqlSessionFactory.openSession();
            // 2.3 获取 Mapper
            UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
            // 2.4 调用方法
            User u = userMapper.selectByUserName(username);
    
            // 3. 判断用户对象是否为 null
            if (u == null) {
                // 用户名不存在,添加用户
                userMapper.add(user);
                // 提交事务
                sqlSession.commit();
            } else {
                // 用户名存在,给出提示信息
                response.setContentType("text/html;charset=utf-8");
                response.getWriter().write("用户名已存在");
            }
            // 释放资源
            sqlSession.close();
        }
    
        @Override
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            this.doGet(request, response);
        }
    }
    复制代码

代码优化

  • 创建 SqlSessionFactory 代码优化
    • 代码重复:工具类
    • SqlSessionFacroty 工厂只创建一次,不要重复创建:静态代码块
    package com.ruochen.util;
    
    import org.apache.ibatis.io.Resources;
    import org.apache.ibatis.session.SqlSessionFactory;
    import org.apache.ibatis.session.SqlSessionFactoryBuilder;
    
    import java.io.IOException;
    import java.io.InputStream;
    
    public class SqlSessionFactoryUtils {
    
        private static SqlSessionFactory sqlSessionFactory;
    
        static {
            // 静态代码块会随着类的加载自动执行,且只执行一次
    
            try {
                String resource = "mybatis-config.xml";
                InputStream inputStream = Resources.getResourceAsStream(resource);
                sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        public static SqlSessionFactory getSqlSessionFactory() {
            return sqlSessionFactory;
        }
    }
    复制代码

案例

准备工作

  • 创建新的模块 brand_demo,引入坐标
  • pom.xml
    <?xml version="1.0" encoding="UTF-8"?>
    <project xmlns="http://maven.apache.org/POM/4.0.0"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
        <modelVersion>4.0.0</modelVersion>
    
        <groupId>com.ruochen</groupId>
        <artifactId>brand-demo</artifactId>
        <version>1.0-SNAPSHOT</version>
        <packaging>war</packaging>
    
        <properties>
            <maven.compiler.source>8</maven.compiler.source>
            <maven.compiler.target>8</maven.compiler.target>
        </properties>
    
        <dependencies>
            <!--mybatis-->
            <dependency>
                <groupId>org.mybatis</groupId>
                <artifactId>mybatis</artifactId>
                <version>3.5.5</version>
            </dependency>
    
            <!--mysql-->
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <version>5.1.34</version>
            </dependency>
    
            <!--servlet-->
            <dependency>
                <groupId>javax.servlet</groupId>
                <artifactId>javax.servlet-api</artifactId>
                <version>3.1.0</version>
                <scope>provided</scope>
            </dependency>
    
            <!--jsp-->
            <dependency>
                <groupId>javax.servlet.jsp</groupId>
                <artifactId>jsp-api</artifactId>
                <version>2.2</version>
                <scope>provided</scope>
            </dependency>
    
            <!--jstl-->
            <dependency>
                <groupId>jstl</groupId>
                <artifactId>jstl</artifactId>
                <version>1.2</version>
            </dependency>
    
            <!--standard-->
            <!--jstl 1.2 版本不需要此依赖-->
            <!--
            <dependency>
                <groupId>taglibs</groupId>
                <artifactId>standard</artifactId>
                <version>1.1.2</version>
            </dependency>
            -->
        </dependencies>
    
        <build>
            <plugins>
                <plugin>
                    <groupId>org.apache.tomcat.maven</groupId>
                    <artifactId>tomcat7-maven-plugin</artifactId>
                    <version>2.1</version>
                </plugin>
            </plugins>
        </build>
    
    </project>
    复制代码
  • 创建三层架构的包结构
  • 数据库表 tb_brand
    -- 创建数据库
    create database db1 character set utf8;
    use db1;
    
    -- 删除tb_brand表
    drop table if exists tb_brand;
    -- 创建tb_brand表
    create table tb_brand
    (
        -- id 主键
        id           int primary key auto_increment,
        -- 品牌名称
        brand_name   varchar(20),
        -- 企业名称
        company_name varchar(20),
        -- 排序字段
        ordered      int,
        -- 描述信息
        description  varchar(100),
        -- 状态:0:禁用  1:启用
        status       int
    );
    -- 添加数据
    insert into tb_brand (brand_name, company_name, ordered, description, status)
    values ('三只松鼠', '三只松鼠股份有限公司', 5, '好吃不上火', 0),
           ('华为', '华为技术有限公司', 100, '华为致力于把数字世界带入每个人、每个家庭、每个组织,构建万物互联的智能世界', 1),
           ('小米', '小米科技有限公司', 50, 'are you ok', 1);
    
    
    SELECT * FROM tb_brand;
    复制代码
  • 实体类 Brand
    package com.ruochen.pojo;
    
    /**
     * 品牌实体类
     */
    
    public class Brand {
        // id 主键
        private Integer id;
        // 品牌名称
        private String brandName;
        // 企业名称
        private String companyName;
        // 排序字段
        private Integer ordered;
        // 描述信息
        private String description;
        // 状态:0:禁用  1:启用
        private Integer status;
    
    
        public Brand() {
        }
    
        public Brand(Integer id, String brandName, String companyName, String description) {
            this.id = id;
            this.brandName = brandName;
            this.companyName = companyName;
            this.description = description;
        }
    
        public Brand(Integer id, String brandName, String companyName, Integer ordered, String description, Integer status) {
            this.id = id;
            this.brandName = brandName;
            this.companyName = companyName;
            this.ordered = ordered;
            this.description = description;
            this.status = status;
        }
    
        public Integer getId() {
            return id;
        }
    
        public void setId(Integer id) {
            this.id = id;
        }
    
        public String getBrandName() {
            return brandName;
        }
    
        public void setBrandName(String brandName) {
            this.brandName = brandName;
        }
    
        public String getCompanyName() {
            return companyName;
        }
    
        public void setCompanyName(String companyName) {
            this.companyName = companyName;
        }
    
        public Integer getOrdered() {
            return ordered;
        }
    
        public void setOrdered(Integer ordered) {
            this.ordered = ordered;
        }
    
        public String getDescription() {
            return description;
        }
    
        public void setDescription(String description) {
            this.description = description;
        }
    
        public Integer getStatus() {
            return status;
        }
    
        public void setStatus(Integer status) {
            this.status = status;
        }
    
        @Override
        public String toString() {
            return "Brand{" +
                    "id=" + id +
                    ", brandName='" + brandName + '\'' +
                    ", companyName='" + companyName + '\'' +
                    ", ordered=" + ordered +
                    ", description='" + description + '\'' +
                    ", status=" + status +
                    '}';
        }
    }
    复制代码
  • MyBatis 基础环境
    • MyBatis-config.xml
    <?xml version="1.0" encoding="UTF-8" ?>
    <!DOCTYPE configuration
            PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
            "http://mybatis.org/dtd/mybatis-3-config.dtd">
    <configuration>
        <!--起别名-->
        <typeAliases>
            <package name="com.ruochen.pojo"/>
        </typeAliases>
    
        <environments default="development">
            <environment id="development">
                <transactionManager type="JDBC"/>
                <dataSource type="POOLED">
                    <property name="driver" value="com.mysql.jdbc.Driver"/>
                    <property name="url"
                          value="jdbc:mysql:///db1?useSSL=false&amp;useServerPrepStmts=true&amp;useUnicode=true&amp;characterEncoding=UTF-8"/>
                    <property name="username" value="root"/>
                    <property name="password" value="ruochen666"/>
                </dataSource>
            </environment>
        </environments>
        <mappers>
            <!--扫描mapper-->
            <package name="com.ruochen.mapper"/>
        </mappers>
    </configuration>
    复制代码
    • BrandMapper.xml
    <?xml version="1.0" encoding="UTF-8" ?>
    <!DOCTYPE mapper
            PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
            "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
    <mapper namespace="com.ruochen.mapper.BrandMapper">
    
    </mapper>
    复制代码
    • BrandMapper 接口
    package com.ruochen.mapper;
    
    public interface BrandMapper {
    }
    复制代码
  • 目录树如下

业务 - 查询所有

  • Dao 层:BrandMapper
        /**
         * 查询所有
         * @return
         */
        @Select("select * from tb_brand")
        @ResultMap("brandResultMap")
        List<Brand> selectAll();
    复制代码
    • BrandMapper.xml
    <?xml version="1.0" encoding="UTF-8" ?>
    <!DOCTYPE mapper
            PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
            "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
    <mapper namespace="com.ruochen.mapper.BrandMapper">
    
        <resultMap id="brandResultMap" type="brand">
            <result column="brand_name" property="brandName"></result>
            <result column="company_name" property="companyName"></result>
        </resultMap>
    </mapper>
    复制代码
  • 工具类:SqlSessionFactoryUtils
    package com.ruochen.utils;
    
    import org.apache.ibatis.io.Resources;
    import org.apache.ibatis.session.SqlSessionFactory;
    import org.apache.ibatis.session.SqlSessionFactoryBuilder;
    
    import java.io.IOException;
    import java.io.InputStream;
    
    public class SqlSessionFactoryUtils {
    
        private static SqlSessionFactory sqlSessionFactory;
    
        static {
            //静态代码块会随着类的加载而自动执行,且只执行一次
    
            try {
                String resource = "mybatis-config.xml";
                InputStream inputStream = Resources.getResourceAsStream(resource);
                sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    
    
        public static SqlSessionFactory getSqlSessionFactory(){
            return sqlSessionFactory;
        }
    }
    复制代码
  • Service 层:BrandService
    package com.ruochen.service;
    
    import com.ruochen.mapper.BrandMapper;
    import com.ruochen.pojo.Brand;
    import com.ruochen.utils.SqlSessionFactoryUtils;
    import org.apache.ibatis.session.SqlSession;
    import org.apache.ibatis.session.SqlSessionFactory;
    
    import java.util.List;
    
    public class BrandService {
        // 1. 获取 sqlSessionFactory
        SqlSessionFactory factory = SqlSessionFactoryUtils.getSqlSessionFactory();
    
        /**
         * 查询所有功能
         * @return
         */
        public List<Brand> selectAll() {
            // 调用BrandMapper.selectAll()
            // 2. 获取 SqlSession
            SqlSession sqlSession = factory.openSession();
            // 3. 获取 BrandMapper
            BrandMapper mapper = sqlSession.getMapper(BrandMapper.class);
            // 4. 调用方法
            List<Brand> brands = mapper.selectAll();
            // 5. 释放资源
            sqlSession.close();
    
            return brands;
        }
    }
    复制代码
  • Web 层
    • index.html
    <!DOCTYPE html>
    <html lang="en">
        <head>
            <meta charset="UTF-8">
            <title>Title</title>
        </head>
        <body>
            <a href="/brand-demo/selectAllServlet">查询所有</a>
    
        </body>
    </html>
    复制代码
    • SelectAllServlet
    package com.ruochen.web;
    
    import com.ruochen.pojo.Brand;
    import com.ruochen.service.BrandService;
    
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import java.io.IOException;
    import java.util.List;
    
    @WebServlet("/selectAllServlet")
    public class SelectAllServlet extends HttpServlet {
    	private BrandService brandService = new BrandService();
    	
        @Override
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            // 1. 调用 BrandService 完成查询
            List<Brand> brands = brandService.selectAll();
    
            // 2. 存入request域中
            request.setAttribute("brand", brands);
    
            // 3. 转发到 brand.jsp
            request.getRequestDispatcher("/brand.jsp").forward(request, response);
    
        }
    
        @Override
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            this.doGet(request, response);
        }
    }
    复制代码
    • brand.jsp
    <%--
      Created by IntelliJ IDEA.
      User: ruochen
      Date: 2022/2/27
      Time: 12:33
      To change this template use File | Settings | File Templates.
    --%>
    <%@ page contentType="text/html;charset=UTF-8" language="java" %>
    <%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
    <html>
        <head>
            <title>Title</title>
        </head>
        <body>
            <input type="button" value="新增"><br>
            <hr>
            <table border="1" cellspacing="0" width="80%">
                <tr>
                    <th>序号</th>
                    <th>品牌名称</th>
                    <th>企业名称</th>
                    <th>排序</th>
                    <th>品牌介绍</th>
                    <th>状态</th>
                    <th>操作</th>
                </tr>
    
                <c:forEach items="${brands}" var="brand" varStatus="status">
                    <tr align="center">
                        <td>${status.count}</td>
                        <td>${brand.brandName}</td>
                        <td>${brand.companyName}</td>
                        <td>${brand.ordered}</td>
                        <td>${brand.description}</td>
                        <c:if test="${brand.status == 1}">
                            <td>启用</td>
                        </c:if>
                        <c:if test="${brand.status != 1}">
                            <td>禁用</td>
                        </c:if>
    
                        <td><a href="#">修改</a> <a href="#">删除</a></td>
                    </tr>
                </c:forEach>
            </table>
        </body>
    </html>
    复制代码
  • 测试 在这里插入图片描述

注意点:resultMap 的使用:属性名称和数据库字段名称不一致

业务 - 添加

  • Dao 层:BrandMapper
        @Insert("insert into tb_brand values (null, #{brandName}, #{companyName}, #{ordered}, #{description}, #{status});")
        void add(Brand brand);
    复制代码
  • Service 层:BrandService
        /**
         * 添加
         * @param brand
         */
        public void add(Brand brand) {
            // 2. 获取 SqlSession
            SqlSession sqlSession = factory.openSession();
            // 3. 获取 BrandMapper
            BrandMapper mapper = sqlSession.getMapper(BrandMapper.class);
            // 4. 调用方法
            mapper.add(brand);
    
            // 提交事务
            sqlSession.commit();
    
            // 释放资源
            sqlSession.close();
        }
    复制代码
  • Web 层:brand.jsp
    <%--
      Created by IntelliJ IDEA.
      User: ruochen
      Date: 2022/2/27
      Time: 12:33
      To change this template use File | Settings | File Templates.
    --%>
    <%@ page contentType="text/html;charset=UTF-8" language="java" %>
    <%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
    <html>
        <head>
            <title>Title</title>
        </head>
        <body>
            <input type="button" value="新增" id="add"><br>
            <hr>
            <table border="1" cellspacing="0" width="80%">
                <tr>
                    <th>序号</th>
                    <th>品牌名称</th>
                    <th>企业名称</th>
                    <th>排序</th>
                    <th>品牌介绍</th>
                    <th>状态</th>
                    <th>操作</th>
                </tr>
    
                <c:forEach items="${brands}" var="brand" varStatus="status">
                    <tr align="center">
                        <td>${status.count}</td>
                        <td>${brand.brandName}</td>
                        <td>${brand.companyName}</td>
                        <td>${brand.ordered}</td>
                        <td>${brand.description}</td>
                        <c:if test="${brand.status == 1}">
                            <td>启用</td>
                        </c:if>
                        <c:if test="${brand.status != 1}">
                            <td>禁用</td>
                        </c:if>
    
                        <td><a href="#">修改</a> <a href="#">删除</a></td>
                    </tr>
                </c:forEach>
            </table>
        </body>
    
        <script>
            document.getElementById("add").onclick = function () {
                location.href = "/brand-demo/addBrand.jsp";
            }
        </script>
    </html>
    复制代码
    • addBrand.jsp
    <%--
      Created by IntelliJ IDEA.
      User: ruochen
      Date: 2022/2/27
      Time: 13:32
      To change this template use File | Settings | File Templates.
    --%>
    <%@ page contentType="text/html;charset=UTF-8" language="java" %>
    <html>
        <head>
            <meta charset="UTF-8">
            <title>添加品牌</title>
        </head>
        <body>
            <h3>添加品牌</h3>
            <form action="/brand-demo/AddServlet" method="post">
                品牌名称:<input name="brandName"><br>
                企业名称:<input name="companyName"><br>
                排序:<input name="ordered"><br>
                描述信息:<textarea rows="5" cols="20" name="description"></textarea><br>
                状态:
                <input type="radio" name="status" value="0">禁用
                <input type="radio" name="status" value="1">启用<br>
    
                <input type="submit" value="提交">
            </form>
        </body>
    </html>
    复制代码
    • AddBrandServlet
    package com.ruochen.web;
    
    import com.ruochen.pojo.Brand;
    import com.ruochen.service.BrandService;
    
    import javax.servlet.*;
    import javax.servlet.http.*;
    import javax.servlet.annotation.*;
    import java.io.IOException;
    
    @WebServlet("/addServlet")
    public class AddServlet extends HttpServlet {
        private BrandService service = new BrandService();
    
        @Override
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            // 1. 接收表单提交的数据,封装为一个 Brand 对象
            String brandName = request.getParameter("brandName");
            String companyName = request.getParameter("companyName");
            String ordered = request.getParameter("ordered");
            String description = request.getParameter("description");
            String status = request.getParameter("status");
    
            Brand brand = new Brand();
            brand.setBrandName(brandName);
            brand.setCompanyName(companyName);
            brand.setOrdered(Integer.parseInt(ordered));
            brand.setDescription(description);
            brand.setStatus(Integer.parseInt(status));
    
            // 2. 调用 service 完成添加
            service.add(brand);
    
            // 3. 转发到查询所有 Servlet
            request.getRequestDispatcher("/selectAllServlet").forward(request, response);
        }
    
        @Override
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            this.doGet(request, response);
        }
    }
    复制代码
  • 测试

业务 - 修改(数据回显)

  • Dao 层:BrandMapper
        /**
         * 根据 id 查询
         * @param id
         * @return
         */
        @Select("select * from tb_brand where id = #{id}")
        @ResultMap("brandResultMap")
        Brand selectById(int id);
    复制代码
  • Service 层:BrandService
        /**
         * 根据 id 查询
         * @param id
         * @return
         */
        public Brand selectById(int id) {
            // 调用BrandMapper.selectAll()
            // 2. 获取 SqlSession
            SqlSession sqlSession = factory.openSession();
            // 3. 获取 BrandMapper
            BrandMapper mapper = sqlSession.getMapper(BrandMapper.class);
            // 4. 调用方法
            Brand brand = mapper.selectById(id);
            // 5. 释放资源
            sqlSession.close();
    
            return brand;
        }
    复制代码
  • Web 层:brand.jsp
    <td><a href="/brand-demo/selectByIdServlet?id=${brand.id}">修改</a> <a href="#">删除</a></td>
    复制代码
    • SelectByIdServlet
    package com.ruochen.web;
    
    import com.ruochen.pojo.Brand;
    import com.ruochen.service.BrandService;
    
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import java.io.IOException;
    
    @WebServlet("/selectByIdServlet")
    public class SelectByIdServlet extends HttpServlet {
        private BrandService brandService = new BrandService();
    
        @Override
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            // 1. 接收id
            String id = request.getParameter("id");
            // 2. 调用 service
            Brand brand = brandService.selectById(Integer.parseInt(id));
            // 3. 存储到 request 中
            request.setAttribute("brand", brand);
            // 4. 转发到 update.jsp
            request.getRequestDispatcher("/update.jsp").forward(request, response);
        }
    
        @Override
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            this.doGet(request, response);
        }
    }
    复制代码
    • update.jsp
    <%--
      Created by IntelliJ IDEA.
      User: ruochen
      Date: 2022/2/27
      Time: 13:32
      To change this template use File | Settings | File Templates.
    --%>
    <%@ page contentType="text/html;charset=UTF-8" language="java" %>
    <%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
    <html>
        <head>
            <meta charset="UTF-8">
            <title>修改品牌</title>
        </head>
        <body>
            <h3>修改品牌</h3>
            <form action="#" method="post">
                品牌名称:<input name="brandName" value="${brand.brandName}"><br>
                企业名称:<input name="companyName" value="${brand.companyName}"><br>
                排序:<input name="ordered" value="${brand.ordered}"><br>
                描述信息:<textarea rows="5" cols="20" name="description">${brand.description}</textarea><br>
                状态:
                <c:if test="${brand.status == 0}">
                    <input type="radio" name="status" value="0" checked>禁用
                    <input type="radio" name="status" value="1">启用<br>
                </c:if>
                <c:if test="${brand.status == 1}">
                    <input type="radio" name="status" value="0">禁用
                    <input type="radio" name="status" value="1" checked>启用<br>
                </c:if>
    
                <input type="submit" value="提交">
            </form>
        </body>
    </html>
    复制代码
  • 测试

业务 - 修改(修改数据)

  • Dao 层:BrandMapper
        /**
         * 修改
         * @param brand
         */
        @Update("update tb_brand set brand_name = #{brandName}, company_name = #{companyName}, ordered = #{ordered}, " +
                "description = #{description}, status = #{status} where id = #{id}")
        void update(Brand brand);
    复制代码
  • Service 层:BrandService
        /**
         * 修改
         * @param brand
         */
        public void update(Brand brand) {
            // 2. 获取 SqlSession
            SqlSession sqlSession = factory.openSession();
            // 3. 获取 BrandMapper
            BrandMapper mapper = sqlSession.getMapper(BrandMapper.class);
            // 4. 调用方法
            mapper.update(brand);
    
            // 提交事务
            sqlSession.commit();
    
            // 释放资源
            sqlSession.close();
        }
    复制代码
  • Web 层:update.jsp
    <%--
      Created by IntelliJ IDEA.
      User: ruochen
      Date: 2022/2/27
      Time: 13:32
      To change this template use File | Settings | File Templates.
    --%>
    <%@ page contentType="text/html;charset=UTF-8" language="java" %>
    <%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
    <html>
        <head>
            <meta charset="UTF-8">
            <title>修改品牌</title>
        </head>
        <body>
            <h3>修改品牌</h3>
            <form action="/brand-demo/updateServlet" method="post">
                <%-- 隐藏域,提交 id --%>
                <input type="hidden" name="id" value="${brand.id}">
                    
                品牌名称:<input name="brandName" value="${brand.brandName}"><br>
                企业名称:<input name="companyName" value="${brand.companyName}"><br>
                排序:<input name="ordered" value="${brand.ordered}"><br>
                描述信息:<textarea rows="5" cols="20" name="description">${brand.description}</textarea><br>
                状态:
                <c:if test="${brand.status == 0}">
                    <input type="radio" name="status" value="0" checked>禁用
                    <input type="radio" name="status" value="1">启用<br>
                </c:if>
                <c:if test="${brand.status == 1}">
                    <input type="radio" name="status" value="0">禁用
                    <input type="radio" name="status" value="1" checked>启用<br>
                </c:if>
    
                <input type="submit" value="提交">
            </form>
        </body>
    </html>
    复制代码
    • updateServlet
    package com.ruochen.web;
    
    import com.ruochen.pojo.Brand;
    import com.ruochen.service.BrandService;
    
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import java.io.IOException;
    
    @WebServlet("/updateServlet")
    public class UpdateServlet extends HttpServlet {
        private BrandService service = new BrandService();
    
        @Override
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    
            // 处理 post 请求的乱码问题
            request.setCharacterEncoding("utf-8");
    
            // 1. 接收表单提交的数据,封装为一个 Brand 对象
            String id = request.getParameter("id");
            String brandName = request.getParameter("brandName");
            String companyName = request.getParameter("companyName");
            String ordered = request.getParameter("ordered");
            String description = request.getParameter("description");
            String status = request.getParameter("status");
    
            Brand brand = new Brand();
            brand.setId(Integer.parseInt(id));
            brand.setBrandName(brandName);
            brand.setCompanyName(companyName);
            brand.setOrdered(Integer.parseInt(ordered));
            brand.setDescription(description);
            brand.setStatus(Integer.parseInt(status));
    
            // 2. 调用 service 完成修改
            service.update(brand);
    
            // 3. 转发到查询所有 Servlet
            request.getRequestDispatcher("/selectAllServlet").forward(request, response);
        }
    
        @Override
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            this.doGet(request, response);
        }
    }
    复制代码
  • 测试

业务 - 删除

  • Dao 层:BrandMapper
        /**
         * 删除
         * @param id
         */
        @Delete("delete from tb_brand where id = #{id}")
        void delete(int id);
    复制代码
  • Service 层:BrandService
        /**
         * 删除
         * @param id
         */
        public void delete(int id) {
            // 2. 获取 SqlSession
            SqlSession sqlSession = factory.openSession();
            // 3. 获取 BrandMapper
            BrandMapper mapper = sqlSession.getMapper(BrandMapper.class);
            // 4. 调用方法
            mapper.delete(id);
    
            // 提交事务
            sqlSession.commit();
    
            // 释放资源
            sqlSession.close();
        }
    复制代码
  • Web 层:brand.jsp
    <td><a href="/brand-demo/selectByIdServlet?id=${brand.id}">修改</a> <a
    href="/brand-demo/deleteServlet?id=${brand.id}">删除</a></td>
    复制代码
    • DeleteServlet
    package com.ruochen.web;
    
    import com.ruochen.pojo.Brand;
    import com.ruochen.service.BrandService;
    
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import java.io.IOException;
    
    @WebServlet("/deleteServlet")
    public class DeleteServlet extends HttpServlet {
        private BrandService service = new BrandService();
    
        @Override
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            // 1. 接收 id
            String id = request.getParameter("id");
            // 2. 调用 service
            service.delete(Integer.parseInt(id));
            // 3. 转发到查询所有 Servlet
            request.getRequestDispatcher("/selectAllServlet").forward(request, response);
        }
    
        @Override
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            this.doGet(request, response);
        }
    }
    复制代码
  • 测试

业务 - 用户登录

  • Dao 层:UserMapper.java
    package com.ruochen.mapper;
    
    import com.ruochen.pojo.User;
    import org.apache.ibatis.annotations.Insert;
    import org.apache.ibatis.annotations.Param;
    import org.apache.ibatis.annotations.Select;
    
    public interface UserMapper {
    
    
        /**
         * 根据用户名和密码查询用户对象
         * @param username
         * @param password
         * @return
         */
        @Select("select * from tb_user where username = #{username} and password = #{password}")
        User select(@Param("username") String username,@Param("password")  String password);
    
        /**
         * 根据用户名查询用户对象
         * @param username
         * @return
         */
        @Select("select * from tb_user where username = #{username}")
        User selectByUsername(String username);
    
        /**
         * 添加用户
         * @param user
         */
        @Insert("insert into tb_user values(null,#{username},#{password})")
        void add(User user);
    }
    复制代码
    • User.java
    package com.ruochen.pojo;
    
    public class User {
    
        private Integer id;
        private String username;
        private String password;
    
        public Integer getId() {
            return id;
        }
    
        public void setId(Integer id) {
            this.id = id;
        }
    
        public String getUsername() {
            return username;
        }
    
        public void setUsername(String username) {
            this.username = username;
        }
    
        public String getPassword() {
            return password;
        }
    
        public void setPassword(String password) {
            this.password = password;
        }
    
        @Override
        public String toString() {
            return "User{" +
                    "id=" + id +
                    ", username='" + username + '\'' +
                    ", password='" + password + '\'' +
                    '}';
        }
    }
    复制代码
    • UserMapper.xml
    <?xml version="1.0" encoding="UTF-8" ?>
    <!DOCTYPE mapper
            PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
            "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
    <mapper namespace="com.ruochen.mapper.UserMapper">
    
    </mapper>
    复制代码
  • Service 层:UserService.java
    package com.ruochen.service;
    
    import com.ruochen.mapper.UserMapper;
    import com.ruochen.pojo.User;
    import com.ruochen.utils.SqlSessionFactoryUtils;
    import org.apache.ibatis.session.SqlSession;
    import org.apache.ibatis.session.SqlSessionFactory;
    
    public class UserService {
        SqlSessionFactory factory = SqlSessionFactoryUtils.getSqlSessionFactory();
    
        /**
         * 登录方法
         * @param username
         * @param password
         * @return
         */
        public User login(String username, String password) {
            // 2. 获取 SqlSession
            SqlSession sqlSession = factory.openSession();
            // 3. 获取 UserMapper
            UserMapper mapper = sqlSession.getMapper(UserMapper.class);
            // 4. 调用方法
            User user = mapper.select(username, password);
            // 5. 释放资源
            sqlSession.close();
    
            return user;
        }
    }
    复制代码
  • Web 层:login.jsp
    <%--
      Created by IntelliJ IDEA.
      User: ruochen
      Date: 2022/2/27
      Time: 15:45
      To change this template use File | Settings | File Templates.
    --%>
    <%@ page contentType="text/html;charset=UTF-8" language="java" %>
    <html>
    
        <head>
            <meta charset="UTF-8">
            <title>login</title>
            <link href="css/login.css" rel="stylesheet">
        </head>
    
        <body>
            <div id="loginDiv" style="height: 350px">
                <form action="/brand-demo/loginServlet" id="form">
                    <h1 id="loginMsg">LOGIN IN</h1>
                    <div id="errorMsg">${login_msg}</div>
                    <p>Username:<input id="username" name="username" type="text"></p>
    
                    <p>Password:<input id="password" name="password" type="password"></p>
                    <p>Remember:<input id="remember" name="remember" type="checkbox"></p>
                    <div id="subDiv">
                        <input type="submit" class="button" value="login up">
                        <input type="reset" class="button" value="reset">&nbsp;&nbsp;&nbsp;
                        <a href="register.html">没有账号?</a>
                    </div>
                </form>
            </div>
    
        </body>
    </html>
    复制代码
    • brand.jsp 添加
    <h1>${user.username},欢迎您</h1>
    复制代码
    • LoginServlet
    package com.ruochen.web;
    
    import com.ruochen.pojo.User;
    import com.ruochen.service.UserService;
    
    import javax.servlet.*;
    import javax.servlet.http.*;
    import javax.servlet.annotation.*;
    import java.io.IOException;
    
    @WebServlet("/loginServlet")
    public class LoginServlet extends HttpServlet {
        private UserService service = new UserService();
    
        @Override
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            // 1. 获取用户名和密码
            String username = request.getParameter("username");
            String password = request.getParameter("password");
    
            // 2. 调用 service 查询
            User user = service.login(username, password);
    
            // 3. 判断
            if (user != null) {
                // 登录成功,,跳转到查询所有的 BrandServlet
    
                // 将登录成功的user对象存储到 session
                HttpSession session = request.getSession();
                session.setAttribute("user", user);
    
                String contextPath = request.getContextPath();
                response.sendRedirect(contextPath + "/selectAllServlet");
            } else {
                // 登录失败
    
                // 存储错误信息到 request
                request.setAttribute("login_msg", "用户名或密码错误");
    
                // 跳转到 login.jsp
                request.getRequestDispatcher("/login.jsp").forward(request, response);
            }
        }
    
        @Override
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            this.doGet(request, response);
        }
    }
    复制代码
  • 测试

业务 - 记住用户

  • 如何自动填充用户名和密码?
    • 将用户名和密码写入Cookie中,并且持久化存储 Cookie,下次访问浏览器会自动携带 Cookie
    • 在页面获取 Cookie 数据后,设置到用户名和密码框中
  • 何时写 Cookie?
    • 登录成功
    • 用户勾选记住用户复选框
  • LoginServlet
    package com.ruochen.web;
    
    import com.ruochen.pojo.User;
    import com.ruochen.service.UserService;
    
    import javax.servlet.*;
    import javax.servlet.http.*;
    import javax.servlet.annotation.*;
    import java.io.IOException;
    
    @WebServlet("/loginServlet")
    public class LoginServlet extends HttpServlet {
        private UserService service = new UserService();
    
        @Override
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            // 1. 获取用户名和密码
            String username = request.getParameter("username");
            String password = request.getParameter("password");
    
            // 获取复选框数据
            String remember = request.getParameter("remember");
    
            // 2. 调用 service 查询
            User user = service.login(username, password);
    
            // 3. 判断
            if (user != null) {
                // 登录成功,,跳转到查询所有的 BrandServlet
    
                // 判断用户是否勾选记住我
                if ("1".equals(remember)) {
                    // 勾选了,发送 Cookie
    
                    // 1. 创建 Cookie 对象
                    Cookie c_username = new Cookie("username", username);
                    Cookie c_password = new Cookie("password", password);
                    // 设置 Cookie 存活时间
                    c_username.setMaxAge(60 * 60 * 24 * 7);
                    c_password.setMaxAge(60 * 60 * 24 * 7);
                    // 2. 发送 Cookie
                    response.addCookie(c_username);
                    response.addCookie(c_password);
                }
                // 将登录成功的user对象存储到 session
                HttpSession session = request.getSession();
                session.setAttribute("user", user);
    
                String contextPath = request.getContextPath();
                response.sendRedirect(contextPath + "/selectAllServlet");
            } else {
                // 登录失败
    
                // 存储错误信息到 request
                request.setAttribute("login_msg", "用户名或密码错误");
    
                // 跳转到 login.jsp
                request.getRequestDispatcher("/login.jsp").forward(request, response);
            }
        }
    
        @Override
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            this.doGet(request, response);
        }
    }
    复制代码
  • login.jsp
    <%--
      Created by IntelliJ IDEA.
      User: ruochen
      Date: 2022/2/27
      Time: 15:45
      To change this template use File | Settings | File Templates.
    --%>
    <%@ page contentType="text/html;charset=UTF-8" language="java" %>
    <html>
    
        <head>
            <meta charset="UTF-8">
            <title>login</title>
            <link href="css/login.css" rel="stylesheet">
        </head>
    
        <body>
            <div id="loginDiv" style="height: 350px">
                <form action="/brand-demo/loginServlet" method="post" id="form">
                    <h1 id="loginMsg">LOGIN IN</h1>
                    <div id="errorMsg">${login_msg}</div>
                    <p>Username:<input id="username" name="username" value="${cookie.username.value}" type="text"></p>
    
                    <p>Password:<input id="password" name="password" value="${cookie.password.value}" type="password"></p>
                    <p>Remember:<input id="remember" name="remember" value="1" type="checkbox"></p>
                    <div id="subDiv">
                        <input type="submit" class="button" value="login up">
                        <input type="reset" class="button" value="reset">&nbsp;&nbsp;&nbsp;
                        <a href="register.html">没有账号?</a>
                    </div>
                </form>
            </div>
    
        </body>
    </html>
    复制代码
  • 测试

业务 - 注册

  • UserService.java
        /**
         * 注册方法
         *
         * @param user
         * @return
         */
        public boolean register(User user) {
            // 2. 获取 SqlSession
            SqlSession sqlSession = factory.openSession();
            // 3. 获取 UserMapper
            UserMapper mapper = sqlSession.getMapper(UserMapper.class);
            // 4. 判断用户名是否存在
            User u = mapper.selectByUsername(user.getUsername());
            if (u == null) {
                // 用户名不存在,注册
                mapper.add(user);
                sqlSession.commit();
            }
            sqlSession.close();
            return u == null;
        }
    复制代码
  • register.jsp
    <%--
      Created by IntelliJ IDEA.
      User: ruochen
      Date: 2022/2/27
      Time: 16:24
      To change this template use File | Settings | File Templates.
    --%>
    <%@ page contentType="text/html;charset=UTF-8" language="java" %>
    <html>
        <head>
            <meta charset="UTF-8">
            <title>欢迎注册</title>
            <link href="css/register.css" rel="stylesheet">
        </head>
        <body>
    
            <div class="form-div">
                <div class="reg-content">
                    <h1>欢迎注册</h1>
                    <span>已有帐号?</span> <a href="login.html">登录</a>
                </div>
                <form id="reg-form" action="/brand-demo/registerServlet" method="post">
    
                    <table>
    
                        <tr>
                            <td>用户名</td>
                            <td class="inputs">
                                <input name="username" type="text" id="username">
                                <br>
                            	<span id="username_err" class="err_msg">${register_msg}</span>
                            </td>
    
                        </tr>
    
                        <tr>
                            <td>密码</td>
                            <td class="inputs">
                                <input name="password" type="password" id="password">
                                <br>
                                <span id="password_err" class="err_msg" style="display: none">密码格式有误</span>
                            </td>
                        </tr>
    
    
                        <tr>
                            <td>验证码</td>
                            <td class="inputs">
                                <input name="checkCode" type="text" id="checkCode">
                                <img src="imgs/a.jpg">
                                <a href="#" id="changeImg">看不清?</a>
                            </td>
                        </tr>
    
                    </table>
    
                    <div class="buttons">
                        <input value="注 册" type="submit" id="reg_btn">
                    </div>
                    <br class="clear">
                </form>
    
            </div>
        </body>
    </html>
    复制代码
  • login.jsp 添加
    <div id="errorMsg">${login_msg} ${register_msg}</div>
    <a href="register.jsp">没有账号?</a>
    复制代码
  • RegisterServlet
    package com.ruochen.web;
    
    import com.ruochen.pojo.User;
    import com.ruochen.service.UserService;
    
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.*;
    import java.io.IOException;
    
    @WebServlet("/registerServlet")
    public class RegisterServlet extends HttpServlet {
        private UserService service = new UserService();
    
        @Override
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            // 1. 获取用户名和密码
            String username = request.getParameter("username");
            String password = request.getParameter("password");
    
            User user = new User();
            user.setUsername(username);
            user.setPassword(password);
    
            // 2. 调用 service 注册
            boolean flag = service.register(user);
            // 3. 判断注册成功与否
            if (flag) {
                // 注册成功,跳转登录页面
                request.setAttribute("register_msg", "注册成功,请登录");
                request.getRequestDispatcher("/login.jsp").forward(request, response);
            } else {
                // 注册失败,跳转到注册页面
                request.setAttribute("register_msg", "用户名已存在");
                request.getRequestDispatcher("/register.jsp").forward(request, response);
            }
        }
    
        @Override
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            this.doGet(request, response);
        }
    }
    复制代码
  • 测试

业务 - 注册验证码

  • 验证码工具类:checkCodeUtil.java
    package com.ruochen.utils;
    
    import javax.imageio.ImageIO;
    import java.awt.*;
    import java.awt.geom.AffineTransform;
    import java.awt.image.BufferedImage;
    import java.io.*;
    import java.util.Arrays;
    import java.util.Random;
    
    /**
     * 生成验证码工具类
     */
    public class CheckCodeUtil {
    
        public static final String VERIFY_CODES = "123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        private static Random random = new Random();
    
        /**
         * 输出随机验证码图片流,并返回验证码值(一般传入输出流,响应response页面端,Web项目用的较多)
         *
         * @param w          图片宽度
         * @param h          图片高度
         * @param os         输出流
         * @param verifySize 数据长度
         * @return 验证码数据
         * @throws IOException
         */
        public static String outputVerifyImage(int w, int h, OutputStream os, int verifySize) throws IOException {
            String verifyCode = generateVerifyCode(verifySize);
            outputImage(w, h, os, verifyCode);
            return verifyCode;
        }
    
        /**
         * 使用系统默认字符源生成验证码
         *
         * @param verifySize 验证码长度
         * @return
         */
        public static String generateVerifyCode(int verifySize) {
            return generateVerifyCode(verifySize, VERIFY_CODES);
        }
    
        /**
         * 使用指定源生成验证码
         *
         * @param verifySize 验证码长度
         * @param sources    验证码字符源
         * @return
         */
        public static String generateVerifyCode(int verifySize, String sources) {
            // 未设定展示源的字码,赋默认值大写字母+数字
            if (sources == null || sources.length() == 0) {
                sources = VERIFY_CODES;
            }
            int codesLen = sources.length();
            Random rand = new Random(System.currentTimeMillis());
            StringBuilder verifyCode = new StringBuilder(verifySize);
            for (int i = 0; i < verifySize; i++) {
                verifyCode.append(sources.charAt(rand.nextInt(codesLen - 1)));
            }
            return verifyCode.toString();
        }
    
        /**
         * 生成随机验证码文件,并返回验证码值 (生成图片形式,用的较少)
         *
         * @param w
         * @param h
         * @param outputFile
         * @param verifySize
         * @return
         * @throws IOException
         */
        public static String outputVerifyImage(int w, int h, File outputFile, int verifySize) throws IOException {
            String verifyCode = generateVerifyCode(verifySize);
            outputImage(w, h, outputFile, verifyCode);
            return verifyCode;
        }
    
    
        /**
         * 生成指定验证码图像文件
         *
         * @param w
         * @param h
         * @param outputFile
         * @param code
         * @throws IOException
         */
        public static void outputImage(int w, int h, File outputFile, String code) throws IOException {
            if (outputFile == null) {
                return;
            }
            File dir = outputFile.getParentFile();
            //文件不存在
            if (!dir.exists()) {
                //创建
                dir.mkdirs();
            }
            try {
                outputFile.createNewFile();
                FileOutputStream fos = new FileOutputStream(outputFile);
                outputImage(w, h, fos, code);
                fos.close();
            } catch (IOException e) {
                throw e;
            }
        }
    
        /**
         * 输出指定验证码图片流
         *
         * @param w
         * @param h
         * @param os
         * @param code
         * @throws IOException
         */
        public static void outputImage(int w, int h, OutputStream os, String code) throws IOException {
            int verifySize = code.length();
            BufferedImage image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
            Random rand = new Random();
            Graphics2D g2 = image.createGraphics();
            g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
    
            // 创建颜色集合,使用java.awt包下的类
            Color[] colors = new Color[5];
            Color[] colorSpaces = new Color[]{Color.WHITE, Color.CYAN,
                    Color.GRAY, Color.LIGHT_GRAY, Color.MAGENTA, Color.ORANGE,
                    Color.PINK, Color.YELLOW};
            float[] fractions = new float[colors.length];
            for (int i = 0; i < colors.length; i++) {
                colors[i] = colorSpaces[rand.nextInt(colorSpaces.length)];
                fractions[i] = rand.nextFloat();
            }
            Arrays.sort(fractions);
            // 设置边框色
            g2.setColor(Color.GRAY);
            g2.fillRect(0, 0, w, h);
    
            Color c = getRandColor(200, 250);
            // 设置背景色
            g2.setColor(c);
            g2.fillRect(0, 2, w, h - 4);
    
            // 绘制干扰线
            Random random = new Random();
            // 设置线条的颜色
            g2.setColor(getRandColor(160, 200));
            for (int i = 0; i < 20; i++) {
                int x = random.nextInt(w - 1);
                int y = random.nextInt(h - 1);
                int xl = random.nextInt(6) + 1;
                int yl = random.nextInt(12) + 1;
                g2.drawLine(x, y, x + xl + 40, y + yl + 20);
            }
    
            // 添加噪点
            // 噪声率
            float yawpRate = 0.05f;
            int area = (int) (yawpRate * w * h);
            for (int i = 0; i < area; i++) {
                int x = random.nextInt(w);
                int y = random.nextInt(h);
                // 获取随机颜色
                int rgb = getRandomIntColor();
                image.setRGB(x, y, rgb);
            }
            // 添加图片扭曲
            shear(g2, w, h, c);
    
            g2.setColor(getRandColor(100, 160));
            int fontSize = h - 4;
            Font font = new Font("Algerian", Font.ITALIC, fontSize);
            g2.setFont(font);
            char[] chars = code.toCharArray();
            for (int i = 0; i < verifySize; i++) {
                AffineTransform affine = new AffineTransform();
                affine.setToRotation(Math.PI / 4 * rand.nextDouble() * (rand.nextBoolean() ? 1 : -1), (w / verifySize) * i + fontSize / 2, h / 2);
                g2.setTransform(affine);
                g2.drawChars(chars, i, 1, ((w - 10) / verifySize) * i + 5, h / 2 + fontSize / 2 - 10);
            }
    
            g2.dispose();
            ImageIO.write(image, "jpg", os);
        }
    
        /**
         * 随机颜色
         *
         * @param fc
         * @param bc
         * @return
         */
        private static Color getRandColor(int fc, int bc) {
            if (fc > 255) {
                fc = 255;
            }
            if (bc > 255) {
                bc = 255;
            }
            int r = fc + random.nextInt(bc - fc);
            int g = fc + random.nextInt(bc - fc);
            int b = fc + random.nextInt(bc - fc);
            return new Color(r, g, b);
        }
    
        private static int getRandomIntColor() {
            int[] rgb = getRandomRgb();
            int color = 0;
            for (int c : rgb) {
                color = color << 8;
                color = color | c;
            }
            return color;
        }
    
        private static int[] getRandomRgb() {
            int[] rgb = new int[3];
            for (int i = 0; i < 3; i++) {
                rgb[i] = random.nextInt(255);
            }
            return rgb;
        }
    
        private static void shear(Graphics g, int w1, int h1, Color color) {
            shearX(g, w1, h1, color);
            shearY(g, w1, h1, color);
        }
    
        private static void shearX(Graphics g, int w1, int h1, Color color) {
    
            int period = random.nextInt(2);
    
            boolean borderGap = true;
            int frames = 1;
            int phase = random.nextInt(2);
    
            for (int i = 0; i < h1; i++) {
                double d = (double) (period >> 1)
                        * Math.sin((double) i / (double) period
                        + (6.2831853071795862D * (double) phase)
                        / (double) frames);
                g.copyArea(0, i, w1, 1, (int) d, 0);
                if (borderGap) {
                    g.setColor(color);
                    g.drawLine((int) d, i, 0, i);
                    g.drawLine((int) d + w1, i, w1, i);
                }
            }
    
        }
    
        private static void shearY(Graphics g, int w1, int h1, Color color) {
    
            int period = random.nextInt(40) + 10; // 50;
    
            boolean borderGap = true;
            int frames = 20;
            int phase = 7;
            for (int i = 0; i < w1; i++) {
                double d = (double) (period >> 1)
                        * Math.sin((double) i / (double) period
                        + (6.2831853071795862D * (double) phase)
                        / (double) frames);
                g.copyArea(i, 0, 1, h1, 0, (int) d);
                if (borderGap) {
                    g.setColor(color);
                    g.drawLine(i, (int) d, i, 0);
                    g.drawLine(i, (int) d + h1, i, h1);
                }
    
            }
    
        }
    }
    复制代码
  • register.jsp
    <tr>
        <td>验证码</td>
        <td class="inputs">
            <input name="checkCode" type="text" id="checkCode">
            <img id="checkCodeImg" src="/brand-demo/checkCodeServlet">
            <a href="#" id="changeImg">看不清?</a>
        </td>
    </tr>
    <script>
        document.getElementById("changeImg").onclick = function () {
            document.getElementById("checkCodeImg").src = "/brand-demo/checkCodeServlet?" + new Date().getMilliseconds();
        };
    
        document.getElementById("checkCodeImg").onclick = function () {
            document.getElementById("checkCodeImg").src = "/brand-demo/checkCodeServlet?" + new Date().getMilliseconds();
        };
    </script>
    复制代码
  • CheckCodeServlet.java
    package com.ruochen.web;
    
    import com.ruochen.utils.CheckCodeUtil;
    
    import javax.servlet.ServletException;
    import javax.servlet.ServletOutputStream;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import javax.servlet.http.HttpSession;
    import java.io.IOException;
    
    @WebServlet("/checkCodeServlet")
    public class CheckCodeServlet extends HttpServlet {
        @Override
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            // 生成验证码
            ServletOutputStream os = response.getOutputStream();
            String checkCode = CheckCodeUtil.outputVerifyImage(100, 50, os, 4);
    
            // 存入 session
            HttpSession session = request.getSession();
            session.setAttribute("checkCodeGen", checkCode);
    
        }
    
        @Override
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            this.doGet(request, response);
        }
    }
    复制代码
  • RegisterServlet.java
    package com.ruochen.web;
    
    import com.ruochen.pojo.User;
    import com.ruochen.service.UserService;
    
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.*;
    import java.io.IOException;
    
    @WebServlet("/registerServlet")
    public class RegisterServlet extends HttpServlet {
        private UserService service = new UserService();
    
        @Override
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            // 1. 获取用户名和密码
            String username = request.getParameter("username");
            String password = request.getParameter("password");
    
            User user = new User();
            user.setUsername(username);
            user.setPassword(password);
    
            // 获取用户输入的验证码
            String checkCode = request.getParameter("checkCode");
    
            // 程序生成的验证码,从 session 获取
            HttpSession session = request.getSession();
            String checkCodeGen = (String) session.getAttribute("checkCodeGen");
    
            // 比对
            if (!checkCodeGen.equalsIgnoreCase(checkCode)) {
                request.setAttribute("register_msg", "验证码错误");
                request.getRequestDispatcher("/register.jsp").forward(request, response);
    
                // 不允许注册
                return;
            }
    
            // 2. 调用 service 注册
            boolean flag = service.register(user);
            // 3. 判断注册成功与否
            if (flag) {
                // 注册成功,跳转登录页面
                request.setAttribute("register_msg", "注册成功,请登录");
                request.getRequestDispatcher("/login.jsp").forward(request, response);
            } else {
                // 注册失败,跳转到注册页面
                request.setAttribute("register_msg", "用户名已存在");
                request.getRequestDispatcher("/register.jsp").forward(request, response);
            }
        }
    
        @Override
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            this.doGet(request, response);
        }
    }
    复制代码
  • 测试

业务 - 登录验证

  • LoginFilter
    package com.ruochen.web.filter;
    
    import javax.servlet.*;
    import javax.servlet.annotation.*;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpSession;
    import java.io.IOException;
    
    /**
     * 登录验证的过滤器
     */
    @WebFilter("/*")
    public class LoginFilter implements Filter {
        @Override
        public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws ServletException, IOException {
    
            HttpServletRequest req = (HttpServletRequest) request;
            // 判断访问资源路径是否和登录注册相关
            String[] urls = {"/login.jsp", "/imgs/", "/css/", "/loginServlet", "/register.jsp", "/registerServlet", "/checkCodeServlet"};
            // 获取当前访问的资源路径
            String url = req.getRequestURL().toString();
            // 循环判断
            for (String u : urls) {
                if (url.contains(u)) {
                    // 包含
                    // 放行
                    chain.doFilter(request, response);
                    return;
                }
            }
    
            // 1. 判断 session 中是否有 user
            HttpSession session = req.getSession();
            Object user = session.getAttribute("user");
    
            // 2. 判断user是否为 null
            if (user != null) {
                // 已登录
                // 放行
                chain.doFilter(request, response);
            } else {
                // 未登录,存储提示信息,跳转到登录页面
                req.setAttribute("login_msg", "您尚未登录!");
                req.getRequestDispatcher("/login.jsp").forward(req, response);
            }
    
        }
    
        public void init(FilterConfig config) throws ServletException {
        }
    
        public void destroy() {
        }
    
    }
    复制代码
  • 测试
分类:
后端
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分类:
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