MyBatis学习笔记（三）查询集合配置

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第一节中查询的方法返回类型为Student，当返回类型为List<Student>时怎么办呢？

这时需要配置resultMap标签．

<?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:Mapper映射 --><!-- 这个文件感觉就像StudentMapper接口的实现一样，只是从java文件变成了xml文件充当了Dao类的功能 --><mapper namespace="com.skymr.mybatis.mappers.StudentMapper"><select id="getStudent" parameterType="int" resultType="Student"><!-- mybatis要自己写sql语句 -->select * from mybatis_Student where id=#{id}</select><!-- 查询所有学生 --><!-- resultMap属性要对应 resultMap的id属性 --><select id="getAllStudents" resultMap="studentMap">select * from mybatis_Student</select><resultMap type="Student" id="studentMap"><id property="id" column="id"/><result property="name" column="name"/><result property="age" column="age"/></resultMap></mapper>

package com.skymr.mybatis.mappers;import java.util.List;import com.skymr.mybatis.model.Student;public interface StudentMapper {public Student getStudent(int id);public List<Student> getAllStudents();}

package com.skymr.mybatis.service;import java.util.List;import org.apache.ibatis.session.SqlSession;import org.junit.After;import org.junit.Before;import org.junit.Test;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import com.skymr.mybatis.mappers.StudentMapper;import com.skymr.mybatis.model.Student;import com.skymr.mybatis.util.MybatisUtil;public class StudentTest2 {private Logger logger = LoggerFactory.getLogger(StudentTest2.class);private SqlSession session;@Beforepublic void beforeTest(){session = MybatisUtil.openSession();}@Afterpublic void afterTest(){session.close();}@Testpublic void testGetAllStudents(){logger.info("测试取得所有学生");StudentMapper mapper = session.getMapper(StudentMapper.class);List<Student> list = mapper.getAllStudents();logger.info(list.toString());}}

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