MyBatis篇】四. MyBatis高级第三章 注解开发（共三章）

MyBatis高级第三章 注解开发

github源码(day56-mybatis-senior) https://github.com/1196557363/ideaMavenProject
【MyBatis篇】四. MyBatis高级第一章 #{}和${}符号的区别
【MyBatis篇】四. MyBatis高级第二章 缓存

项目准备

1. 因为在同一个module中所以大环境不用改,参考第一章的项目准备
2. 将接口com.wpj.dao.IUserDao2 改为 com.wpj.dao3.IUserDao2 已示区分知识点
3. 注解开发可以不用mapper映射文件
4. MyBatis的mapper映射记得加。

1. Select

1.1 MyBatis.xml

<mappers>
	<mapper resource="mapper/IUserDao2.xml"/>
	<mapper resource="mapper2/IUserDao2.xml"/>
	<!--如果是注解开发这里要写接口-->
	<mapper class="com.wpj.dao3.IUserDao2" />
</mappers>

1.2 IUserDao2接口

package com.wpj.dao3;

import com.wpj.bean.*;
import org.apache.ibatis.annotations.*;

/**
 * ClassName: IUserDao2
 * Description:
 *
 * @author JieKaMi
 * @version 1.0
 * @date: 2020\1\7 0007 19:02
 * @since JDK 1.8
 */
public interface IUserDao2 {

    @Select(value="select * from user where id = #{id}")
    User getUserById(Integer id);
}

1.3 test

import com.wpj.bean.*;

import com.wpj.dao3.*;
import org.apache.ibatis.io.*;
import org.apache.ibatis.session.*;
import org.junit.*;

import java.io.*;

/**
 * ClassName: MyBatisTest
 * Description:
 *
 * @author JieKaMi
 * @version 1.0
 * @date: 2020\1\7 0007 19:19
 * @since JDK 1.8
 */
public class MyBatisTest3 {
    @Test
    public void testGetUserById(){
        String config = "MyBatis.xml";
        InputStream is = null;
        try {
            is = Resources.getResourceAsStream(config);
            SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
            SqlSession sqlSession = sqlSessionFactory.openSession();
            IUserDao2 userDao = sqlSession.getMapper(IUserDao2.class);
            User user = userDao.getUserById(1);

            System.out.println(user);
            sqlSession.close();

        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if(is!=null) {
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

2 Results

@Results(value={
        @Result(id =true, property="id", column="id"),
        @Result(property="name", column="name"),
        @Result(property="pwd", column="pwd"),
        @Result(property="age", column="age")})
@Select(value="select * from user where id = #{id}")
User getUserById(Integer id);

3 ResultMap复用

@Results(id="userResults",value={
        @Result(id =true, property="id", column="id"),
        @Result(property="name", column="name"),
        @Result(property="pwd", column="pwd"),
        @Result(property="age", column="age")})
@Select(value="select * from user where id = #{id}")
User getUserById(Integer id);


@ResultMap("userResults")
User getUserById2(Integer id);