Mybatis-02

2024-02-11 18:06:28

Mybatis

CRUD操作

　　在写完第一个Mybatis程序后，我们对Mybatis也有了一定的认识，也逐渐了解了Mybatis的强大之处。接下来，我们来进行传统的增删改查操作来全面地展示Mybatis。

mapper接口层代码

package com.charles.dao;

import com.charles.pojo.UserInfo;

import java.util.List;

public interface UserMapper {

    // 查询所有用户
    List<UserInfo> queryAll();

    // 通过id查询用户
    UserInfo queryUserById(int iduserInfo);

    // 添加一个用户
    int addUser(UserInfo userInfo);

    // 修改一个用户
    int updateUser(UserInfo userInfo);

    // 删除一个用户
    int deleteUser(int iduserInfo);

}

SQL语句

<?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.charles.dao.UserMapper">
    <select id="queryAll" resultType="com.charles.pojo.UserInfo">
        select * from userinfo;
    </select>

    <select id="queryUserById" resultType="com.charles.pojo.UserInfo">
        select * from userinfo where iduserInfo=#{iduserInfo};
    </select>

    <insert id="addUser" parameterType="com.charles.pojo.UserInfo">
        insert into userinfo values(#{iduserInfo},#{username},#{password},#{perms});
    </insert>

    <update id="updateUser" parameterType="com.charles.pojo.UserInfo">
        update userinfo set username=#{username},password=#{password},perms=#{perms} where iduserInfo=#{iduserInfo};
    </update>

    <delete id="deleteUser" parameterType="int">
        delete from userinfo where iduserInfo=#{iduserInfo};
    </delete>
</mapper>

测试类：

package com.charles.dao;

import com.charles.pojo.UserInfo;
import com.charles.utils.MybatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.List;

public class UserInfoDaoTest {

    @Test
    public void queryAll(){
        SqlSession session = MybatisUtils.getSession();
        UserMapper mapper = session.getMapper(UserMapper.class);
        List<UserInfo> userInfos = mapper.queryAll();

        for (UserInfo user : userInfos){
            System.out.println(user);
        }

        // 使用后需要及时关闭，跟JDBC差不多.
        session.close();
    }

    // 通过Id查询用户
    @Test
    public void queryUserById(){
        SqlSession session = MybatisUtils.getSession();
        UserMapper mapper = session.getMapper(UserMapper.class);
        UserInfo userInfo = mapper.queryUserById(2);
        System.out.println(userInfo);
        session.close();
    }

    // 添加一个用户
    @Test
    public void addUser(){
        SqlSession session = MybatisUtils.getSession();
        UserMapper mapper = session.getMapper(UserMapper.class);
        int cc = mapper.addUser(new UserInfo(4, "CC", "123", "user:null"));
        if (cc > 0) System.out.println("添加成功！！");
        else System.out.println("添加失败~~");
        // 一定要提交，否则数据无效
        session.commit();
        session.close();
    }

    // 修改一个用户
    @Test
    public void updateUser(){
        SqlSession session = MybatisUtils.getSession();
        UserMapper mapper = session.getMapper(UserMapper.class);
        int charles = mapper.updateUser(new UserInfo(1, "Charles", "1234", "user:gold"));
        if (charles>0) System.out.println("修改成功");
        else System.out.println("修改失败");
        session.commit();
        session.close();
    }

    // 删除一个用户
    @Test
    public void deleteUser(){
        SqlSession session = MybatisUtils.getSession();
        UserMapper mapper = session.getMapper(UserMapper.class);
        int i = mapper.deleteUser(4);
        if (i>0) System.out.println("删除成功");
        else System.out.println("用户不存在");
        session.commit();
        session.close();
    }

}

结果展示：

　　1. 通过Id查询