Mybatis_接口编程

Mybatis参考使用文档：http://www.mybatis.org/mybatis-3/zh/index.html

1.项目结构

2.新增EmployeeMapper.java接口代码

package com.atguigu.mybatis.dao;import com.atguigu.mybatis.bean.Employee;public interface EmployeeMapper {public Employee getEmpById(Integer id);}

3.EmployeeMapper.xml改动

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.atguigu.mybatis.dao.EmployeeMapper">
<!-- 
namespace:名称空间;  指定接口全类名
id:唯一标识
resultType：返回值类型
#{id}：从传递过来的参数中取出id值 public Employee getEmpById();
--><select id="getEmpById" resultType="com.atguigu.mybatis.bean.Employee">select id,last_name lastName,email,gender from tbl_employee where id = #{id}</select>
</mapper>

①namespace指定接口全名
②id指定接口方法

3.MybatisTest.java

package com.atguigu.mybatis.test;import java.io.IOException;
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.atguigu.mybatis.bean.Employee;
import com.atguigu.mybatis.dao.EmployeeMapper;public class MybatisTest {private SqlSessionFactory getSqlSessionFactory() throws IOException {String resource = "mybatis-config.xml";InputStream inputStream = Resources.getResourceAsStream(resource);return new SqlSessionFactoryBuilder().build(inputStream);}@Testpublic void test02() throws IOException {/*1.创建sqlSessionFactory对象*/SqlSessionFactory sqlSessionFactory =getSqlSessionFactory();/*2.获取SqlSession对象*/SqlSession openSession= sqlSessionFactory.openSession();try {/*3.获取接口的实现对象*/EmployeeMapper mapper=openSession.getMapper(EmployeeMapper.class);//mapper为代理对象，执行增删改查Employee employee=mapper.getEmpById(1);System.out.println(employee);} finally {openSession.close();}}
}