JavaWeb_(Mybatis框架)Mapper动态代理开发_三

　　MyBatis Mapper动态代理开发4+1 (4大原则+1注意)：

　　　　1、接口方法名需要与mapper.xml的要调用的sql语句的id一致；
　　　　2、接口的形参类型需要与mapper.xml parameterType一致；
　　　　3、接口的返回值需要与mapper.xml resultType一致；
　　　　4、mapper.xml中namespace要与接口的全包名一致；
　　　　5、注意mapper动态代理开发中，根据返回值类型来自动选择；

　　在Dao层开发，需要写一个接口，需要写一个实现类，需要一个Mapper.xml三个文件才能操作数据库

　　Mapper动态代理只需要实现一个接口和一个配置文件，就可以实现以上操作

一、通过 id查询用户

<?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.Gary.mapper.UserMapper">
 
     <select id="selectUserById" parameterType="Integer" resultType="com.Gary.bean.User">
         select * from user where u_id = #{id}
     </select>
     
     <!-- #{}占位符 尽量使用#{}来解决问题 -->
     <!-- ${}字符串拼接   容易sql注入 (or 1 = 1) -->
     
     <!-- ${value}中间的字符串一定需要使用value -->
     <select id="selectUserByName" parameterType="String" resultType="com.Gary.bean.User">
         <!-- select * from user where u_username like '%${value}%' -->
              select * from user where u_username like "%"#{name}"%"
     </select>
     
     <!-- 添加用户 参数为全包名 -->
     <insert id="insertUser" parameterType="com.Gary.bean.User">
         insert into user values(null,#{u_username},#{u_password},#{u_sex},#{u_createTime},#{u_cid})
     </insert>
     
    <!-- 根据id修改username字段的语句 -->
     <update id="updateUser" parameterType="com.Gary.bean.User">
         update user set u_username = #{u_username} where u_id = #{u_id}
     </update>
     
     <!-- 根据id删除用户 -->
     <delete id="deleteUserById" parameterType="Integer">
         delete from user where u_id = #{id}
     </delete>
     
</mapper>

UserMapper.xml

package com.Gary.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.Gary.bean.User;
import com.Gary.mapper.UserMapper;

public class MapperTest {

    @Test
    public void Test1() throws IOException {
        //读取配置文件
        String resource = "sqlMapConfig.xml";
                
        InputStream in = Resources.getResourceAsStream(resource);
                
        //创建sqlSessionFactory
        SqlSessionFactory ssf = new SqlSessionFactoryBuilder().build(in);
                
        //生产一个sqlSession
        SqlSession session = ssf.openSession();
                
        UserMapper mapper = session.getMapper(UserMapper.class);
        
        User user = mapper.selectUserById(1);
        
        System.out.println(user);
        
    }
    
}

MapperTest.java

二、通过名字模糊查询用户列表

<?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.Gary.mapper.UserMapper">
 
     <select id="selectUserById" parameterType="Integer" resultType="com.Gary.bean.User">
         select * from user where u_id = #{id}
     </select>
     
     <!-- #{}占位符 尽量使用#{}来解决问题 -->
     <!-- ${}字符串拼接   容易sql注入 (or 1 = 1) -->
     
     <!-- ${value}中间的字符串一定需要使用value -->
     <select id="selectUserByName" parameterType="String" resultType="com.Gary.bean.User">
         <!-- select * from user where u_username like '%${value}%' -->
              select * from user where u_username like "%"#{name}"%"
     </select>
     
     <!-- 添加用户 参数为全包名 -->
     <insert id="insertUser" parameterType="com.Gary.bean.User">
         insert into user values(null,#{u_username},#{u_password},#{u_sex},#{u_createTime},#{u_cid})
     </insert>
     
    <!-- 根据id修改username字段的语句 -->
     <update id="updateUser" parameterType="com.Gary.bean.User">
         update user set u_username = #{u_username} where u_id = #{u_id}
     </update>
     
     <!-- 根据id删除用户 -->
     <delete id="deleteUserById" parameterType="Integer">
         delete from user where u_id = #{id}
     </delete>
     
</mapper>

UserMapper.xml

package com.Gary.test;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;

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.Gary.bean.User;
import com.Gary.mapper.UserMapper;

public class MapperTest2 {

    @Test
    public void Test2() throws IOException {
        //读取配置文件
        String resource = "sqlMapConfig.xml";
                
        InputStream in = Resources.getResourceAsStream(resource);
                
        //创建sqlSessionFactory
        SqlSessionFactory ssf = new SqlSessionFactoryBuilder().build(in);
                
        //生产一个sqlSession
        SqlSession session = ssf.openSession();
                
        UserMapper mapper = session.getMapper(UserMapper.class);
        
        List<User> list = mapper.selectUserByName("王");
        
        for(User u : list) {
            System.out.println(u);
        }
        
    }
    
}

MapperTest2.java

JavaWeb_(Mybatis框架)Mapper动态代理开发_三

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