mybatis实现增删改查

在第一次实现对数据库的查询后，练习了对数据库的增删改查；修改UserMapper接口文件和UserMapper.xml文件。还需修改测试文件进行测试

UserMapper.java

package dao;

import pojo.User;

import java.util.List;

public interface UserMapper {
    //查询全部用户
    List<User> getUserList();
    //根据ID查询用户
    User getUserById(int id);
    //插入一个用户
    int addUser(User user);
    //修改用户
    int updateUser(User user);
    //删除用户
    int deleteUser(int id);
}

UserMapper.xml

<?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">
<!--namespace=绑定一个对应的Dao/Mapper接口-->
<mapper namespace="dao.UserMapper">
    <!--id为接口方法，resultType为返回值类型,parameterType参数类型-->
    <select id="getUserList" resultType="pojo.User">
        select * from mybatis.user
    </select>
    <select id="getUserById" parameterType="int" resultType="pojo.User">
        select * from mybatis.user where id = #{id}

    </select>
    <!--对象中的属性可以直接取出来-->
    <insert id="addUser" parameterType="pojo.User">
        insert into mybatis.user (id,name,pwd) values (#{id},#{name},#{pwd})
    </insert>
    <update id="updateUser" parameterType="pojo.User">
        update mybatis.user set name =#{name},pwd=#{pwd} where id = #{id}
    </update>
    <delete id="deleteUser" parameterType="int">
        delete from mybatis.user where id=#{id}
    </delete>
</mapper>

测试文件：UserDaoTest.java

package dao;

import org.apache.ibatis.session.SqlSession;
import org.junit.Test;
import pojo.User;
import utils.MybatisUtils;

import java.util.List;

public class UserDaoTest {
    @Test
    public  void test()
    {
        //获得SqlSession对象
        SqlSession sqlSession=MybatisUtils.getSqlSession();
        //执行Sql

        UserMapper userMapper=sqlSession.getMapper(UserMapper.class);
        List<User> userList=userMapper.getUserList();

        for(User user:userList)
        {
            System.out.println(user.getId());
        }
        //关闭SqlSession
        sqlSession.close();
    }
    @Test
    public void getUserById()
    {
        //获得SqlSession对象
        SqlSession sqlSession=MybatisUtils.getSqlSession();

        //获得接口
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        User user=mapper.getUserById(1);
        System.out.println(user.getName());

        //关闭SqlSession
        sqlSession.close();
    }
    //增删改需要提交事务
    @Test
    public void addUser()
    {
        //获得SqlSession对象
        SqlSession sqlSession=MybatisUtils.getSqlSession();

        //获得接口
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        int flag=mapper.addUser(new User(3,"苗可卓3","3"));
        if(flag>0)
        {
            System.out.println("插入成功");
        }
        //提交事务
        sqlSession.commit();
        //关闭SqlSession
        sqlSession.close();
    }
    @Test
    public void updateUser()
    {
        //获得SqlSession对象
        SqlSession sqlSession=MybatisUtils.getSqlSession();

        //获得接口
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        int flag=mapper.updateUser(new User(1,"苗迪","miaodi"));
        if(flag>0)
        {
            System.out.println("修改成功");
        }
        //提交事务
        sqlSession.commit();
        //关闭SqlSession
        sqlSession.close();
    }
    @Test
    public void deleteUser()
    {
        //获得SqlSession对象
        SqlSession sqlSession=MybatisUtils.getSqlSession();

        //获得接口
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        int flag=mapper.deleteUser(1);
        if(flag>0)
        {
            System.out.println("删除成功");
        }
        //提交事务
        sqlSession.commit();
        //关闭SqlSession
        sqlSession.close();
    }
}

 注意事项，在Sql的CRUD操作中，增删改需要提交事务。