SSM整合初体验

【流程参考自b站狂神说】

一、整合Mybatis层

1. 建数据库

CREATE DATABASE ssmbuild;
USE ssmbuild;
CREATE TABLE books(
bookID INT NOT NULL AUTO_INCREMENT COMMENT '书id',
bookName VARCHAR(100) NOT NULL COMMENT '书名',
bookCounts INT NOT NULL COMMENT '数量',
detail VARCHAR(200) NOT NULL COMMENT '描述',
KEY bookID(bookID)
)ENGINE=INNODB** DEFAULT CHARSET=utf8;

INSERT INTO books(bookID,bookName,bookCounts,detail)VALUES
(1,'Java',1,'从入门到放弃'),
(2,'MySQL',10,'从删库到跑路'),
(3,'Linux',5,'从进门到进牢');

2. 构建普通Maven项目

3. 配置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>org.example</groupId>
    <artifactId>ssmbuild</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>

    <!--依赖：junit，数据库驱动，连接池，servlet，jsp，mybatis，mybatis-spring，spring-->
    <dependencies>

        <!--Junit-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>

        <!--数据库驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.29</version>
        </dependency>

        <!--数据库连接池-->
        <dependency>
            <groupId>com.mchange</groupId>
            <artifactId>c3p0</artifactId>
            <version>0.9.5.5</version>
        </dependency>

        <!--Servlet - jsp-->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>servlet-api</artifactId>
            <version>2.5</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet.jsp</groupId>
            <artifactId>jsp-api</artifactId>
            <version>2.2</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
            <version>1.2</version>
        </dependency>

        <!--Mybatis-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.10</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
            <version>2.0.7</version>
        </dependency>

        <!--Spring-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.3.23</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>5.3.23</version>
        </dependency>


        <!--lombok-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.22</version>
        </dependency>

    </dependencies>


    <!--静态资源导出问题-->
    <build>
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>false</filtering>
            </resource>
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>false</filtering>
            </resource>
        </resources>
    </build>

</project>

4. 连接数据库

5. 建包

6. 配置tomcat+检查lib目录是否存在

配置tomcat

检查lib目录是否存在【无lib目录未导包，将无法开启tomcat】

7. database.propertoes【记得要改url的数据库名字ssmbuild！！！】

jdbc.driver=com.mysql.cj.jdbc.Driver
# 如果使用的是MySQL8.0+,在url最后加上时区配置，不然容易报错：&serverTimezone=Asia/Shanghai
jdbc.url=jdbc:mysql://localhost:3306/ssmbuild?useSSL=false&useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai
jdbc.username=root
jdbc.password=lcy150

8. mybatis-config.xml、applicationContext.xml、XXXMapper.xml格式

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>

</configuration>

applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd">

    <import resource="classpath:spring-dao.xml"/>
    <import resource="classpath:spring-service.xml"/>
    <import resource="classpath:spring-mvc.xml"/>

</beans>

XXXMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="com.lcy.dao.XXXMapper">



</mapper>

9. 建实体类

package com.lcy.pojo;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@AllArgsConstructor
@NoArgsConstructor
public class Books {
    private int bookId;
    private String bookName;
    private int bookCounts;
    private String detail;
}

10. 在mybatis-config.xml设置别名

<?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>
    <!--配置数据源，交给Spring去做-->

    <!--别名-->
    <typeAliases>
        <package name="com.lcy.pojo"/>
    </typeAliases>

</configuration>

==============================准备工作👆============================

==============================dao层👇==============================

11. 在dao层创建接口，设置方法

package com.lcy.dao;

import com.lcy.pojo.Books;
import org.apache.ibatis.annotations.Param;

import java.util.List;

public interface BookMapper {
    //增加一本书
    int addBook(Books books);

    //删除一本书
    int deleteBookById(@Param("bookId") int id);

    //更新一本书
    int updateBook(Books books);

    //查询一本书
    Books queryBookById(@Param("bookId") int id);

    //查询全部的书
    List<Books> queryAllBook();

}

12. 在dao层编写BookMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="com.lcy.dao.BookMapper">

    <insert id="addBook" parameterType="Books">
        insert into ssmbuild.books(bookID, bookName, bookCounts, detail)
        VALUES (#{bookID},#{bookName},#{bookCounts},#{detail});
    </insert>
    
    <delete id="deleteBookById" parameterType="int">
        delete from ssmbuild.books where bookID = #{bookId}
    </delete>

    <update id="updateBook" parameterType="Books">
        update ssmbuild.books
        set bookName = #{bookName},bookCounts = #{bookCounts},detail = #{detail}
        where bookID = #{bookID};
    </update>

    <select id="queryBookById" resultType="Books">
        select * from ssmbuild.books where bookID = #{bookId}
    </select>

    <select id="queryAllBook" resultType="Books">
        select * from ssmbuild.books
    </select>

</mapper>

13. 在mybatis-config.xml中绑定mapper

<!--绑定mapper-->
<mappers>
    <mapper class="com.lcy.dao.BookMapper"/>
</mappers>

============================service业务层👇==========================

14. 在service创建BookService接口

package com.lcy.service;

import com.lcy.pojo.Books;

import java.util.List;

public interface BookService {
    //增加一本书
    int addBook(Books books);

    //删除一本书
    int deleteBookById(int id);

    //更新一本书
    int updateBook(Books books);

    //查询一本书
    Books queryBookById(int id);

    //查询全部的书
    List<Books> queryAllBook();
}

15. 在service层创建BookServiceImpl实现BookService接口

package com.lcy.service;

import com.lcy.dao.BookMapper;
import com.lcy.pojo.Books;

import java.util.List;

public class BookServiceImpl implements BookService {

    //service调dao层：组合dao层
    private BookMapper bookMapper;

    public void setBookMapper(BookMapper bookMapper) {
        this.bookMapper = bookMapper;
    }


    
    @Override
    public int addBook(Books books) {
        return bookMapper.addBook(books);
    }

    @Override
    public int deleteBookById(int id) {
        return bookMapper.deleteBookById(id);
    }

    @Override
    public int updateBook(Books books) {
        return bookMapper.updateBook(books);
    }

    @Override
    public Books queryBookById(int id) {
        return bookMapper.queryBookById(id);
    }

    @Override
    public List<Books> queryAllBook() {
        return bookMapper.queryAllBook();
    }
}

【即：Service层调用dao层】

二、整合Spring层

1. spring-dao.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd">

    <!--1.关联数据库配置文件-->
    <context:property-placeholder location="classpath:database.properties"/>

    <!--2.连接池
        dbcp:半自动化操作，不能自动连接
        c3p0:自动化操作，自动化加载配置文件，并且可以自动设置到对象中
        druid:
        hikari:
    -->
    <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="driverClass" value="${jdbc.driver}"/>
        <property name="jdbcUrl" value="${jdbc.url}"/>
        <property name="user" value="${jdbc.username}"/>
        <property name="password" value="${jdbc.password}"/>

        <!--c3p0连接池的私有属性-->
        <property name="maxPoolSize" value="30"/>
        <property name="minPoolSize" value="10"/>
        <!--关闭连接后不自动commit-->
        <property name="autoCommitOnClose" value="false"/>
        <!--获取连接超时时间-->
        <property name="checkoutTimeout" value="10000"/>
        <!--当获取连接失败重试次数-->
        <property name="acquireRetryAttempts" value="2"/>
    </bean>


    <!--3.sqlSessionFactory-->
    <bean id = "sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <!--引用上面的dataSource-->
        <property name="dataSource" ref="dataSource"/>
        <!--绑定Mybatis的配置文件-->
        <property name="configLocation" value="classpath:mybatis-config.xml"/>
    </bean>

    <!--4.配置dao接口扫描包，动态的实现了dao接口可以注入到Spring容器中-->
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <!--注入sqlSessionFactory-->
        <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"/>
        <!--要扫描的dao包-->
        <property name="basePackage" value="com.lcy.dao"/>
    </bean>

</beans>

2. spring-service.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd">

    <!--1.扫描service层下的包-->
    <context:component-scan base-package="com.lcy.service"/>
    
    <!--2.将所有业务类注入到Spring，可以通过配置或注解实现-->
    <bean id="BookServiceImpl" class="com.lcy.service.BookServiceImpl">
        <property name="bookMapper" ref="bookMapper"/>
    </bean>

    <!--3.声明式事务配置-->
    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <!--注入数据源-->
        <property name="dataSource" ref="dataSource"/>
    </bean>

    <!--4.aop事务支持-->


</beans>

三、整合SpringMVC层

1. 加入web支持

2. 配置web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">

    <!--DispatchServlet-->
    <servlet>
        <servlet-name>applicationContext</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:applicationContext.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>applicationContext</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>

    <!--配置解决中文乱码过滤-->
    <filter>
        <filter-name>encodingFilter</filter-name>
        <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
        <init-param>
            <param-name>encoding</param-name>
            <param-value>utf-8</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>encodingFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

    <!--Session-->
    <session-config>
        <session-timeout>15</session-timeout>
    </session-config>

</web-app>

3. 配置spring-mvc.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc.xsd">

    <!--1.注解驱动-->
    <mvc:annotation-driven/>

    <!--2.静态资源过滤-->
    <mvc:default-servlet-handler/>

    <!--3.扫描包：controller-->
    <context:component-scan base-package="com.lcy.controller"/>

    <!--4.视图解析器-->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <property name="suffix" value=".jsp"/>
    </bean>

</beans>

四、实际业务（controller层）

1. 写controller层，BookController.class

package com.lcy.controller;

import com.lcy.pojo.Books;
import com.lcy.service.BookService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import java.util.List;

@Controller
@RequestMapping("/book")
public class BookController {
    //controller 调 service
    @Autowired
    @Qualifier("BookServiceImpl")
    private BookService bookService;

    //查询全部书籍，并返回书籍展示页面
    @RequestMapping("/allBook")
    public String list(Model model){

        List<Books> list = bookService.queryAllBook();

        model.addAttribute("list",list);

        return "allBook";
    }

}

2. 写jsp页面：在web-WEB-INF-jsp中写allBook.jsp，在web写index.jsp

allBook.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>书籍展示</title>
</head>
<body>

<h1>书籍展示</h1>

</body>
</html>

index.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
  <head>
    <title>首页</title>
  </head>
  <body>
    <a href="${pageContext.request.contextPath}/book/allBook">进入书籍页面</a>
  </body>
</html>

3. 此时启动报错

问题：bean不存在

排错步骤：

1. 查看这个bean注入是否成功 在BookController中点击，可成功跳转至spring-service.xml，说明bean注入成功

2. Junit单元测试，看我们的代码是否能查询出来结果【MyTest.class】

import com.lcy.pojo.Books;
import com.lcy.service.BookService;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class MyTest {
    @Test
    public void test(){
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        BookService bookServiceImpl = (BookService) context.getBean("BookServiceImpl");
        for (Books books : bookServiceImpl.queryAllBook()) {
            System.out.println(books);
        }

    }
}

此处我代码报错，查询后发现问题：

• ① applicationContext.xml为空，没有import进spring的三个xml文件，更正如下

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd">

    <import resource="classpath:spring-dao.xml"/>
    <import resource="classpath:spring-service.xml"/>
    <import resource="classpath:spring-mvc.xml"/>

</beans>

• ② spring-dao.xml和spring-service.xml的beans标签有xmlns:context，但是下面没有 www.springframework.org/schema/cont… www.springframework.org/schema/cont…
• 更正：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd">

• ③ spring-mvc.xml中beans标签的xmlns:context和xmlns:mvc顺序写反了，且下方地址也要一一对应
• 更正：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc.xsd">

• ④之前打开可以连接数据库，过几天打开显示数据库连接失败，首页跳转报500错误： 记得先点开Database的表连上数据库！！！

测试成功

3. 上述两个点排除问题后，可确定底层没问题，此时有可能是spring出了问题

4. SpringMVC，整合的时候没调用到service层的bean：

• ① applicationContext.xml没有注入xml【2.①已解决】
• ② web.xml中我们也绑定过配置文件！查看web.xml可知是只绑定了spring-mvc.xml，而没有绑定整合后的applicationContext.xml 【spring-mvc.xml中并没有service bean，所以报空指针】 更正：

<!--DispatchServlet-->
<servlet>
    <servlet-name>applicationContext</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:applicationContext.xml</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
    <servlet-name>applicationContext</servlet-name>
    <url-pattern>/</url-pattern>
</servlet-mapping>