Mybatis20_Mybatis的增删改查操作3

一、MyBatis的插入数据操作

　1. 编写UserMapper映射文件

<?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="userMapper">
    <!--查询操作-->
    <select id="findAll" resultType="com.itheima.domain.User">
        select * from user
    </select>
    <!--插入操作-->
    <insert id="add" parameterType="com.itheima.domain.User">
        insert into user values(#{id},#{username},#{password})
    </insert>
</mapper>

　2. 编写插入实体User的代码

package com.itheima.test;

import com.itheima.domain.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 org.junit.Test;
import java.io.IOException;
import java.io.InputStream;
import java.util.List;

public class MyBatisTest {

    @Test
    public void test2() throws IOException {
        //模拟user对象
        User user = new User();
        user.setUsername("tom");
        user.setPassword("abc");
        InputStream resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
        SqlSession sqlSession = sqlSessionFactory.openSession();
        int insert = sqlSession.insert("userMapper.add", user);
        System.out.println(insert);
        //mybatis执行更新操作 提交事务
        sqlSession.commit();
        sqlSession.close();
    }
}

　　执行test2，检查插入成功：

　3. 插入操作注意问题

• 插入语句使用insert标签
• 在映射文件中使用parameterType属性指定要插入的数据类型
• Sql语句中使用#{实体属性名}方式引用实体中的属性值
• 插入操作使用的API是sqlSession.insert(“命名空间.id”,实体对象);
• 插入操作涉及数据库数据变化，所以要使用sqlSession对象显示的提交事务，即sqlSession.commit()

二、MyBatis的修改数据操作

　1. 编写UserMapper映射文件

<?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="userMapper">
    <!--查询操作-->
    <select id="findAll" resultType="com.itheima.domain.User">
        select * from user
    </select>
    <!--插入操作-->
    <insert id="add" parameterType="com.itheima.domain.User">
        insert into user values(#{id},#{username},#{password})
    </insert>
    <!--修改操作-->
    <update id="update" parameterType="com.itheima.domain.User">
        update user set username=#{username},password=#{password} where id=#{id}
    </update>
</mapper>

　2. 编写修改实体User的代码

package com.itheima.test;

import com.itheima.domain.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 org.junit.Test;
import java.io.IOException;
import java.io.InputStream;
import java.util.List;

public class MyBatisTest {

    @Test
    //修改操作
    public void test3() throws IOException {
        //模拟user对象
        User user = new User();
        user.setId(6);
        user.setUsername("lucy");
        user.setPassword("123");
        InputStream resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
        SqlSession sqlSession = sqlSessionFactory.openSession();
        int update = sqlSession.update("userMapper.update", user);
        System.out.println(update);
        sqlSession.commit();
        sqlSession.close();
    }
}

　　执行test3，检查结果：

　3. 修改操作注意问题

• 修改语句使用update标签
• 修改操作使用的API是sqlSession.update(“命名空间.id”,实体对象);

三、MyBatis的删除数据操作

　1. 编写UserMapper映射文件

<?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="userMapper">
    <!--查询操作-->
    <select id="findAll" resultType="com.itheima.domain.User">
        select * from user
    </select>
    <!--插入操作-->
    <insert id="add" parameterType="com.itheima.domain.User">
        insert into user values(#{id},#{username},#{password})
    </insert>
    <!--修改操作-->
    <update id="update" parameterType="com.itheima.domain.User">
        update user set username=#{username},password=#{password} where id=#{id}
    </update>
    <!--删除操作 #{}里面随便写-->
    <delete id="delete" parameterType="java.lang.Integer">
        delete from user where id=#{id}
    </delete>
</mapper>

　2. 编写删除数据的代码

package com.itheima.test;

import com.itheima.domain.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 org.junit.Test;
import java.io.IOException;
import java.io.InputStream;
import java.util.List;

public class MyBatisTest {

    @Test
    //删除操作
    public void test4() throws IOException {
        InputStream resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
        SqlSession sqlSession = sqlSessionFactory.openSession();
        int delete = sqlSession.delete("userMapper.delete", 6);
        System.out.println(delete);
        sqlSession.commit();
        sqlSession.close();
    }
}

　　执行test4，检查结果：

　3. 删除操作注意问题

• 删除语句使用delete标签
• Sql语句中使用#{任意字符串}方式引用传递的单个参数，根据多个条件删除时则传递的仍旧是User对象，那么parameterType=User
• 删除操作使用的API是sqlSession.delete(“命名空间.id”,Object);

四、知识小结