详解MyBatis开发Dao层的两种方式（Mapper动态代理方式）

<?  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.xyfer.mapper.UserMapper\">
  <!-- 根据id查询用户 -->
  <select id=\"getUserById\" parameterType=\"int\" resultType=\"com.xyfer.po.User\">
    select * from user where id = #{id}
  </select>
  <!-- 添加用户 -->
  <insert id=\"insertUser\" parameterType=\"com.xyfer.po.User\">
  <selectKey keyProperty=\"id\" order=\"AFTER\" resultType=\"java.lang.Integer\">
    select LAST_INSERT_ID() 
  </selectKey>
   insert into user(username,birthday,sex,address) 
   values(#{username},#{birthday},#{sex},#{address})
  </insert>
  <!-- 修改用户 -->
  <update id=\"updateUser\" parameterType=\"com.xyfer.po.User\">
    update user set username=#{username},birthday=#{birthday},sex=#{sex},address=#{address}
    where id=#{id}
  </update>
  <!-- 删除用户 -->
  <delete id=\"deleteUserById\" parameterType=\"int\">
    delete from user where id=#{id}
  </delete>
 </mapper>

package com.xyfer.mapper;

import com.xyfer.po.User;

public interface UserMapper {
  
  public User getUserById(int id);  //根据id值查询一个用户
  public void insertUser(User user); //新增一个用户
  public void updateUser(User user); //修改一个用户
  public void deleteUser(int id);  //删除一个用户

}

<mappers>
  <mapper resource=\"UserMapper. \"/>
</mappers>

package com.xyfer.mapper;

import static org.junit.Assert.*;

import java.io.InputStream;
import java.util.Date;

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.Before;
import org.junit.Test;

import com.xyfer.po.User;

import junit. work.TestCase;

public class UserMapperTest extends TestCase{

  private SqlSessionFactory sqlSessionFactory;
  
  protected void setUp() throws Exception {
    SqlSessionFactoryBuilder sessionFactoryBuilder = new SqlSessionFactoryBuilder();
    InputStream inputStream = Resources.getResourceAsStream(\"SqlMapConfig. \");
    sqlSessionFactory = sessionFactoryBuilder.build(inputStream);
  }


  @Test
  public void testGetUserById() {
    //获取sqlsession
    SqlSession sqlsession = sqlSessionFactory.openSession();
    //获取UserMapper接口代理对象
    UserMapper userMapper = sqlsession.getMapper(UserMapper.class);
    //调用代理对象方法
    User user = userMapper.getUserById(10);
    //打印结果
    System.out.println(user);
    //关闭sqlsession
    sqlsession.close();
  }

  @Test
  public void testInsertUser() {
    //获取sqlsession
    SqlSession sqlsession = sqlSessionFactory.openSession();
    //获取UserMapper接口代理对象
    UserMapper userMapper = sqlsession.getMapper(UserMapper.class);
    //新建一个对象
    User user = new User();
    user.setUsername(\"小谢\");
    user.setSex(\"男\");
    user.setBirthday(new Date());
    user.setAddress(\"浙江省杭州市\");
    //调用代理对象方法
    userMapper.insertUser(user);
    //关闭sqlsession
    sqlsession.close();
  }

  @Test
  public void testUpdateUser() {
    //获取sqlsession
    SqlSession sqlsession = sqlSessionFactory.openSession();
    //获取UserMapper接口代理对象
    UserMapper userMapper = sqlsession.getMapper(UserMapper.class);
    //新建一个对象
    User user = new User();
    user.setUsername(\"小谢\");
    user.setSex(\"男\");
    user.setBirthday(new Date());
    user.setAddress(\"上海市\");
    //调用代理对象方法
    userMapper.updateUser(user);
    //关闭sqlsession
    sqlsession.close();
  }

  @Test
  public void testDeleteUser() {
    //获取sqlsession
    SqlSession sqlsession = sqlSessionFactory.openSession();
    //获取UserMapper接口代理对象
    UserMapper userMapper = sqlsession.getMapper(UserMapper.class);
    //调用代理对象方法
    userMapper.deleteUser(6);
    //关闭sqlsession
    sqlsession.close();
  }

}