菜鸟mybatis第一个程序

明芫
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才开始学java不久，做的学习记录，不对的地方求大佬指点，课程是b站狂神说

先创建个数据库

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创建普通Maven项目

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创建好后开始配置pom.xml

配置pom.xml

<dependencies>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.46</version>
    </dependency>
    <dependency>
        <groupId>org.mybatis</groupId>
        <artifactId>mybatis</artifactId>
        <version>3.5.2</version>
    </dependency>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.12</version>
    </dependency>
</dependencies>

新建一个modules

image.png

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连接数据库

在子模块的resources下创建连接数据库的xml

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<?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>
    <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://localhost:3306/bookdb?useSSL=false&amp;userUnicode=true&amp;characterEncodeing=UTF-8"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="com/kuang/dao/UserMapper.xml"/>
    </mappers>
</configuration>

创建SqlSession的实例

每个基于 MyBatis 的应用都是以一个 SqlSessionFactory 的实例为核心的

image.png

package com.kuang.utils;

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 java.io.IOException;
import java.io.InputStream;

/**/
public class MyabitsUtils {
    //提升SqlSessionFactory作用域
    private static SqlSessionFactory sqlSessionFactory;

    //从XML中构建 SqlSessionFactory
    static{
        String resource = "mybatis-config.xml";
        try {
            InputStream inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
//    既然有了 SqlSessionFactory，顾名思义，我们可以从中获得 SqlSession 的实例
//    可以通过 SqlSession 实例来直接执行已映射的 SQL 语句
    public static SqlSession getSqlSession(){
        return sqlSessionFactory.openSession();
    }
}

创建pojo

实际就是普通JavaBeans

image.png

package com.kuang.utils;

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 java.io.IOException;
import java.io.InputStream;

/**/
public class MyabitsUtils {
    //提升SqlSessionFactory作用域
    private static SqlSessionFactory sqlSessionFactory;

    //从XML中构建 SqlSessionFactory
    static{
        String resource = "mybatis-config.xml";
        try {
            InputStream inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
//    既然有了 SqlSessionFactory，顾名思义，我们可以从中获得 SqlSession 的实例
//    可以通过 SqlSession 实例来直接执行已映射的 SQL 语句
    public static SqlSession getSqlSession(){
        return sqlSessionFactory.openSession();
    }
}```
package com.kuang.pojo;

//生成实体类
public class User {
    private int id;
    private String name;
    private String pwd;

    public User() {
    }


    public User(int id, String name, String pwd) {
        this.id = id;
        this.name = name;
        this.pwd = pwd;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPwd() {
        return pwd;
    }

    public void setPwd(String pwd) {
        this.pwd = pwd;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + ''' +
                ", pwd='" + pwd + ''' +
                '}';
    }
}

创建UserDao和UserMapper.xml

image.png

package com.kuang.dao;


import com.kuang.pojo.User;

import java.util.List;

public interface UserDao {
    List<User> getUserList();
}

<?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.kuang.dao.UserDao">
    <select id="getUserList" resultType="com.kuang.pojo.User">select * from bookdb.user</select>
</mapper>

最后

在子模块pom加入

<build>
    <resources>
        <resource>
            <directory>src/main/resources</directory>
            <includes>
                <include>**/*.properties</include>
                <include>**/*.xml</include>
            </includes>
            <filtering>false</filtering>
        </resource>
        <resource>
            <directory>src/main/java</directory>
            <includes>
                <include>**/*.properties</include>
                <include>**/*.xml</include>
            </includes>
            <filtering>false</filtering>
        </resource>
    </resources>
</build>

父模块pom

<build>
    <resources>
        <resource>
            <directory>src/main/resources</directory>
            <includes>
                <include>**/*.properties</include>
                <include>**/*.xml</include>
            </includes>
            <filtering>true</filtering>
        </resource>
        <resource>
            <directory>src/main/java</directory>
            <includes>
                <include>**/*.properties</include>
                <include>**/*.xml</include>
            </includes>
            <filtering>true</filtering>
        </resource>
    </resources>
</build>

测试

image.png

package com.kuang.dao;

import com.kuang.pojo.User;
import com.kuang.utils.MyabitsUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.jupiter.api.Test;

import java.util.List;

public class UserDaoTest {
    @Test
    public void test(){
        SqlSession sqlSession = MyabitsUtils.getSqlSession();
            //执行sql
            UserDao userDao = sqlSession.getMapper(UserDao.class);
             //得到返回
            List<User> userList = userDao.getUserList();
        for(User user:userList){
            System.out.println(user);
        }

        //关闭session
        sqlSession.close();
    }
}

结果

image.png

增删改查

UserDao

public interface UserDao {
    //查
    List<User> getUserList();
    User getUserById(int id);
    //增加insert
    int addUser(User user);
    //改
    int UpdateUser(User user);
    //删
    int DeleteUser(int id);
}

UserMapper.xml

<mapper namespace="com.kuang.dao.UserDao">
    <select id="getUserList" resultType="com.kuang.pojo.User">
       select * from bookdb.user
    </select>

    <select id="getUserById" resultType="com.kuang.pojo.User">
      select * from bookdb.user where id = #{id};
    </select>

    <insert id="addUser" parameterType="com.kuang.pojo.User">
        insert into bookdb.user(id,name,pwd,state) values (#{id},#{name},#{pwd},#{state});
    </insert>

    <update id="UpdateUser" parameterType="com.kuang.pojo.User">
        update bookdb.user set name=#{name},pwd=#{pwd} where id=#{id};
    </update>

    <delete id="DeleteUser" parameterType="com.kuang.pojo.User">
        delete from bookdb.user where id=#{id};
    </delete>
</mapper>

UserDaoText

@Test
public void test(){
    //SqlSession
    SqlSession sqlSession = MyabitsUtils.getSqlSession();
    /*方一*/
        //执行sql
        UserDao userDao = sqlSession.getMapper(UserDao.class);
         //得到返回
        List<User> userList = userDao.getUserList();
    /*方一*/
    for(User user:userList){
        System.out.println(user);
    }

    //关闭session
    sqlSession.close();
}
@Test
public void testgetUserById(){
    SqlSession sqlSession = MyabitsUtils.getSqlSession();
    UserDao userDao = sqlSession.getMapper(UserDao.class);
    User users  = userDao.getUserById(1);
    System.out.println(users);
    sqlSession.close();
}
//增
@Test  //增删改需要提交事务
public void testaddUser(){
    SqlSession sqlSession = MyabitsUtils.getSqlSession();
    UserDao userDao = sqlSession.getMapper(UserDao.class);
    int res=userDao.addUser(new User(4,"王五","123456",0));
    if(res>0){
        System.out.println("插入成功");
    }
    sqlSession.commit();
    sqlSession.close();
}
//改UpdateUser
@Test
public void setUpdateUser(){
    SqlSession sqlSession = MyabitsUtils.getSqlSession();
    UserDao userDao = sqlSession.getMapper(UserDao.class);
    int res = userDao.UpdateUser(new User(4,"罗斯","123",0));
    if(res>0){
        System.out.println("修改成功");
    }
    sqlSession.commit();
    sqlSession.close();
}
//删
@Test
public void getDeleteUser(){
    SqlSession sqlSession = MyabitsUtils.getSqlSession();
    UserDao userDao = sqlSession.getMapper(UserDao.class);
    int res = userDao.DeleteUser(4);
    if(res>0){
        System.out.println("删除成功");
    }
    sqlSession.commit();
    sqlSession.close();
}
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