Mybatis面向接口编程、参数传递

╰半夏微凉° 2024-02-18 16:28 9阅读 0赞

先写一个接口：

package com.dw.dao;
    
    import java.util.List;
    
    import com.dw.entity.User;
    
    public interface UserDao {
       public void insertUser(User user);
       public void deleteUser(Integer id);
       public List selectById(Integer id);
       public void updateUser(User user);
    }

这里不再写接口的实现类，通过xml文件，并在其中写入要执行的逻辑的sql语句；通过getMapper()方法可以得到该接口的代理对象：

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">
      <mapper namespace="com.dw.dao.UserDao">  //这里要写接口的类名
         <insert id="insertUser"  parameterType="com.dw.entity.User">
            insert into user(username,password) values(#{username},#{password})
         </insert>
         <delete id="deleteUser" parameterType="com.dw.entity.User">
            delete from user where user.id=#{id}
         </delete>
         <select id="selectById" resultType="com.dw.entity.User">   //id要与接口中的方法名一致
            select * from user as u where u.id=#{id}
         </select>
         <update id="updateUser" parameterType="com.dw.entity.User">
            update user as u set u.username=#{username},u.password=#{password} where u.id=#{id}
         </update>
      </mapper>

测试：

package com.dw.dao.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.dw.dao.UserDao;
    import com.dw.entity.User;
    
    public class daoTest {
    	private SqlSession session;
    	private InputStream inputStream ;
    	private SqlSessionFactory sessionFactory;	
    	private UserDao userDao;
    
    	//测试增删查改
      @Test
      public void testInsert(){
    	  init();  
    	  User user = new User();
    	  user.setUsername("纣王");
    	  user.setPassword("123456");
    	  userDao.insertUser(user);
    	  session.commit();
    	  destory();
      }
      
      @Test
      public void testDelete(){
    	  init();  
          userDao.deleteUser(4);
    	  session.commit();
    	  destory();
      }
     
      @Test
      public void testSelect(){
    	  init();  
          User user = (User)(userDao.selectById(3).iterator().next());
          System.out.println("user:"+user);
    	  session.commit();
    	  destory();
      }  
      
      @Test
      public void testUpdate(){
    	  init();  
          User user = (User)(userDao.selectById(2).iterator().next());
          user.setUsername("张三");
          userDao.updateUser(user);
    	  session.commit();
    	  destory();
      }
      
      
    	private void init(){
    		try {
    			inputStream = Resources.getResourceAsStream("config.xml");
    			sessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
    			session = sessionFactory.openSession();
    			userDao = session.getMapper(UserDao.class);
    		} catch (IOException e) {
    			e.printStackTrace();      <parameterMap type="com.dw.entity.User" id="userMap">
            <parameter property="username"/>
            <parameter property="password"/>
         </parameterMap>
         <insert id="inserMap" parameterMap="userMap">
             insert into user(username,password) values(#{u},#{p})
         </insert> 
    
    }}private void destory(){if(session != null){session.close();}if(inputStream != null){try {inputStream.close();} catch (IOException e) {e.printStackTrace();}}} }
     
     ------------------------------------------------------------------------------------------------------------------- 
     参数传递： 
     1、八种基本类型、POJO类 ，可以用parameterType也可以不用 
     2、Map 类型： 
     可以使用parameterMap ， 也可以不用： 
     使用parameterMap 时： 
     
          <parameterMap type="com.dw.entity.User" id="userMap">
            <parameter property="username"/>
            <parameter property="password"/>
         </parameterMap>
         <insert id="inserMap" parameterMap="userMap">
             insert into user(username,password) values(#{u},#{p})
         </insert> 
    
       @Test
      public void testMap(){
    	  init();  
    	  Map<String, String> mp = new HashMap<String, String>();
    	  mp.put("u", "冷锋");
    	  mp.put("p", "123456");
          userDao.inserMap(mp);
    	  session.commit();
    	  destory();
      }  注意 u 、p参数要一致