<?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="dao.EmployeeDAO"><!-- 命名空间等于接口的完整名字，包名加接口名 -->
  <!-- id要求唯一 
       parameterType:填写实体类的完整名字
  -->
  <!-- 插入语句 -->
  <insert id="save" parameterType="entity.Employee">
   INSERT INTO T_TABLE VALUES(2,#{name},#{age})
  </insert>
  <!-- 根据id查询语句 -->
  <select id="findByID" parameterType="int" resultType="entity.Employee">
   SELECT * FROM T_TABLE WHERE ID=#{id}
  </select>
  <!-- 查询所有结果,不需要参数类型 -->
  <select id="findAll" resultType="entity.Employee">
  SELECT * FROM T_TABLE
  </select>
  <!-- 修改操作 -->
  <update id="modify" parameterType="entity.Employee">
  UPDATE T_TABLE SET NAME=#{name},AGE=#{age} WHERE ID=#{id}
  </update>
  <!-- 删除操作 -->
  <delete id="delete" parameterType="int">
  DELETE FROM T_TABLE WHERE ID=#{ididid} 
  </delete>
  
  <!-- 返回map类型的结果 -->
  <!-- 也可以将返回结果简写成map，map即为java.util.Map -->
  <select id="findOne" parameterType="int" resultType="java.util.Map">
   SELECT * FROM T_TABLE WHERE ID=#{id}
  </select>
  
  <!-- 使用resultMap解决表的字段名和实体类的属性名不一致的情况 -->
  <resultMap id="resultMapID" type="entity.NewEmployee">
    <result property="empID" column="id" />
    <result property="empName" column="name" />
    <result property="empAge" column="age" />
  </resultMap>
  
  <select id="findOneByNewEmp" parameterType="int" resultMap="resultMapID">
  SELECT * FROM T_TABLE WHERE ID=#{id}
  </select>
  
</mapper>

import java.util.List;
import java.util.Map;

import entity.Employee;
import entity.NewEmployee;

/**
 * Mapper映射器
 * @author*/
public interface EmployeeDAO {    
    //将一条数据插入数据库
    public void save(Employee e);
    //查询所有结果
    public List<Employee> findAll();
    //根据id来查找结果
    public Employee findByID(int id);
    //修改操作
    public void modify(Employee e);
    //删除操作
    public void delete(int id);
    //返回类型为map的查询，根据id来查询
    public Map findOne(int id);
    //当表的字段名和实体类的属性名不一致时，根据id来查询
    public NewEmployee findOneByNewEmp(int id);    
}

import java.util.List;
import java.util.Map;

import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Before;
import org.junit.Test;

import dao.EmployeeDAO;
import entity.Employee;
import entity.NewEmployee;

public class testMapper {
        //先拿到sqlSession
        private SqlSession session;
        @Before
        public void init() {
            String config="SqlMapConfig.xml";
            SqlSessionFactoryBuilder ssfb=new SqlSessionFactoryBuilder();
            //读取SqlMapConfig.xml文件，预编译sql写入map
            SqlSessionFactory ssf=ssfb.build(testMapper.class.getClassLoader().getResourceAsStream(config));
            session=ssf.openSession();        
        }
        
        //测试mapper映射器 插入记录
        @Test
        public void test1() {
            //mybatis会返回一个符合mapper映射器要求的对象
            EmployeeDAO dao=session.getMapper(EmployeeDAO.class);            
            Employee e=new Employee();
            e.setName("qiaofeng");
            e.setAge(38);
            //调用对象的插入方法
            dao.save(e);
            //提交事务s
            session.commit();
            session.close();
        }
        /**
         * 查询所有员工操作
         */
        @Test
        public void test2() {
            //mybatis会返回一个符合mapper映射器要求的对象
            EmployeeDAO dao=session.getMapper(EmployeeDAO.class);
            List<Employee> list=dao.findAll();
            System.out.println(list);
            session.close();
        }
        /**
         * 根据ID来查找员工信息
         */
        @Test
        public void test3() {
            EmployeeDAO dao=session.getMapper(EmployeeDAO.class);
            Employee emp=dao.findByID(2);
            System.out.println(emp);
            session.close();
        }
        /**
         * 修改操作
         */
        @Test
        public void test4() {
            EmployeeDAO dao=session.getMapper(EmployeeDAO.class);
            Employee emp=dao.findByID(2);
            emp.setAge(emp.getAge()*2);
            //修改
            dao.modify(emp);
            session.commit();
            session.close();
            
        }
        /**
         * 删除操作
         */
        @Test
        public void test5() {
            EmployeeDAO dao=session.getMapper(EmployeeDAO.class);
            dao.delete(5);
            session.commit();
            session.close();
        }
}