3. mybatis的修改、删除和查询

修改、删除和查询操作

1 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="com.bobo.pojo.User">
    <!-- 添加用户 -->
    <insert id="addUser" parameterType="com.bobo.pojo.User" >
        insert into t_user (username,address,gender)values(#{username},#{address},#{gender})
    </insert>
    <!-- 更新用户信息 -->
    <update id="updateUser" parameterType="com.bobo.pojo.User">
        update t_user set username=#{username} ,address=#{address},gender=#{gender} where id =#{id}
    </update>
    <!--  删除用户信息 -->
    <delete id="deleteUser" >
        delete from t_user where id=#{id}
    </delete>
    <!-- 查询所有用户信息 -->
    <select id="queryAll" resultType="com.bobo.pojo.User">
        select * from t_user
    </select>
    <!-- 根据用户编号查询用户信息 -->
    <select id="queryById" parameterType="java.lang.Integer" resultType="com.bobo.pojo.User">
        select * from t_user where id = #{id}
    </select>
</mapper>

2 测试代码

package com.bobo.test;

import com.bobo.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 org.junit.jupiter.api.Test;


import java.io.InputStream;
import java.util.List;

public class TestDemo01 {

    /**
     * MyBatis案例
     */
   @Test
    public void test01() throws Exception{
        // 1.读取核心配置文件
        InputStream in = Resources.getResourceAsStream("mybatis-cfg.xml");
        // 2.获取一个SqlSessionFactory对象
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(in);
        // 3.获取一个SqlSession对象 基于SqlSessionFactory获取
        SqlSession sqlSession = factory.openSession();
        // 添加数据 ORM框架 面试对象操作
        User user = new User("翠花","深圳福田","2");
        // 4.执行数据库操作 statement= namespace+"."+id
        int count = sqlSession.insert("com.bobo.pojo.User.addUser", user);
        System.out.println("影响的行数..."+count);
        // 5.MyBatis中默认是不会自动提交DML操作的数据的
       sqlSession.commit();
       // 6.关闭会话
       sqlSession.commit();
    }

    @Test
    public void test02() throws Exception{
       InputStream in = Resources.getResourceAsStream("mybatis-cfg.xml");
       SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(in);
        SqlSession sqlSession = factory.openSession();
        User user = new User(19,"翠花","北京海淀","女");
        int i = sqlSession.update("com.bobo.pojo.User.updateUser", user);
        System.out.println("影响的行数:" + i);
        sqlSession.commit();
        sqlSession.close();
    }

    @Test
    public void deleteUser() throws Exception{
        InputStream in = Resources.getResourceAsStream("mybatis-cfg.xml");
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(in);
        SqlSession sqlSession = factory.openSession();
        int i = sqlSession.delete("com.bobo.pojo.User.deleteUser", 20);
        System.out.println("影响的行数:" + i);
        sqlSession.commit();
        sqlSession.close();

    }
    @Test
    public void queryAll() throws Exception{
        InputStream in = Resources.getResourceAsStream("mybatis-cfg.xml");
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(in);
        SqlSession sqlSession = factory.openSession();
        List<User> lists = sqlSession.selectList("com.bobo.pojo.User.queryAll");
        for (User user : lists) {
            System.out.println(user);
        }
        sqlSession.close();

    }

    @Test
    public void queryById() throws Exception{
        InputStream in = Resources.getResourceAsStream("mybatis-cfg.xml");
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(in);
        SqlSession sqlSession = factory.openSession();
        List<User> lists = sqlSession.selectList("com.bobo.pojo.User.queryById",19);
        for (User user : lists) {
            System.out.println(user);
        }
        sqlSession.close();

    }
}