19.mapper代理开发

将UserMapper.java和UserMapper.xml放在同一个目录下，是为了mapper的批量扫描

1.mapper.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">
//namespace必须和UserMapper.java类地址相同
<mapper namespace="com.chinglee.ssm.mapper.UserMapper">
    <select id="findUserByIdMapper" parameterType="int" resultType="com.chinglee.ssm.po.User">
        SELECT * FROM USER WHERE id=#{value}
    </select>
</mapper>

2.UserMapper.java

package com.chinglee.ssm.mapper;

import com.chinglee.ssm.po.User;

/**
 * Created by Administrator on 2017/11/2 0002.
 */
public interface UserMapper {
    public User findUserByIdMapper(int id) throws Exception;
}

3.SqlMapConfig.xml配置批量加载mapper

  <!--批量加载mapper
           指定mapper接口的包名，mybatis自动扫描包下面所有mapper接口进行加载
           遵循一些规范：需要将mapper接口类名和mapper.xml映射文件名称保持一致，且在一个目录中
         前提：使用mapper代理的方法
        -->
        <package name="com.chinglee.ssm.mapper"/>

4.applicationContext.xml中实现mapper的sqlSessionFactory的批量注入。

<!-- mapper批量扫描，从mapper包中扫描出mapper接口，自动创建代理对象并且在spring容器中注册
    遵循规范：将mapper.java和mapper.xml映射文件名称保持一致，且在一个目录中
    自动扫描出来的mapper的bean的id为mapper类名（首字母小写）
    -->
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <!-- 指定扫描的包名，如果扫描多个包，每个包中间使用半角逗号分隔-->
        <property name="basePackage" value="com.chinglee.ssm.mapper"/>
        <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"/>
    </bean>

5.测试

创建UserMapperTest类

package com.chinglee.ssm.mapper;

import org.junit.Before;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

/**
 * Created by Administrator on 2017/11/2 0002.
 */
public class UserMapperTest {
    private ApplicationContext applicationContext;
    @Before
    public void setUp() throws Exception {
       applicationContext=new ClassPathXmlApplicationContext("classpath:spring/applicationContext.xml");

    }

    @Test
    public void findUserByIdMapper() throws Exception {
        UserMapper userMapper= (UserMapper) applicationContext.getBean("userMapper");
        userMapper.findUserByIdMapper(1);

    }

}