4.Mapper接口方式操作数据库

1.UserMapper接口代码　

package com.gzcgxt.oa.mapper;

import java.sql.Savepoint;
import java.util.List;

import com.gzcgxt.oa.domain.User;

public interface UserMapper {
    
    //保存用户
    void save(User u);
    
    //删除用户
    void delete(Integer id);
    
    //修改用户
    void update(User u);
    
    //查询单个对象
    User find(Integer id);
    
    //查询所有对象
    List<User> listAll();
}

2.UserMapper.xml配置文件

<?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.gzcgxt.erp.UserMapper">
    
    <insert id="save">
        INSERT INTO `user` SET name=#{name}
    </insert>
    
    <delete id="delete">
        DELETE FROM `user` WHERE id=#{id}
    </delete>
    
    <update id="update">
        UPDATE `user` SET name=#{name} WHERE id=#{id}
    </update>
    
    <select id="find" resultType="User">
        SELECT * FROM `user` WHERE id=#{id} 
    </select>
    
    <select id="listAll" resultType="User">
        SELECT * FROM `user` ORDER BY id desc
    </select>
    
</mapper>

3.测试代码-查询

package com.gzcgxt.oa.test;

import java.io.InputStream;

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 com.gzcgxt.oa.domain.User;
import com.gzcgxt.oa.mapper.UserMapper;



public class App {
    
    @Test
    public void sayInterface() throws Exception
    {
        InputStream in = Resources.getResourceAsStream("mybatis.xml");
        // 构造mybatis工厂对像
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(in);
        // 获取连接
        SqlSession session = factory.openSession();
        //获取UserMapper接口对象
        UserMapper userMapper = session.getMapper(UserMapper.class);
        //查询指定id用户信息
        User u = userMapper.find(2);
        System.out.println(u);
    }
}

 

4.测试增加　

@Test
    public void saySave() throws Exception
    {
        InputStream in = Resources.getResourceAsStream("mybatis.xml");
        // 构造mybatis工厂对像
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(in);
        // 获取连接
        SqlSession session = factory.openSession();
        //获取UserMapper接口对象
        UserMapper userMapper = session.getMapper(UserMapper.class);
        
        User u=new User();
        u.setName("xxxxxx");

        userMapper.save(u);
    }

DEBUG [main] - ooo Using Connection [com.mysql.jdbc.JDBC4Connection@68fd54a6]
DEBUG [main] - ==> Preparing: INSERT INTO `user` SET name=?
DEBUG [main] - ==> Parameters: xxxxxx(String)