[知了堂学习笔记]_mybatis_03如何快速搭建mybatis框架之二
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5.配置实体类和数据库表的映射文件
MyBatis的映射文件主要关联实体类与数据库表，主要目的是将表返回的数据映射到实体类(封装)
<?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"><!-- 给mapper指定一个唯一的namespace，namespace的值习惯上设置成报名+sql映射文件名 --><mapper namespace="com.zhiliaotang.mybatis.mapper.StudentMapper"> <!-- 解决表的字段名称和实体类属性不一样 --> <!-- MyBatis中多表映射 --> <resultMap type="Student01" id="baseResultMap"> <id column="SNO" property="s_no"/> <result column="SBIRTHDAY" property="s_birthday"/> <result column="SNAME" property="s_name"/> <result column="SSEX" property="s_sex"/> <result column="CLASS" property="s_class"/> </resultMap> <resultMap type="Student" id="Student"> <id column="SNO" property="sno"/> <result column="SNAME" property="sname"/> <result column="SSEX" property="ssex"/> <result column="SBIRTHDAY" property="sBirthday"/> <result column="CLASS" property="clas"/> <association property="teacher" javaType="Teacher"> <id column="TNO" property="tno"/> <result column="TNAME" property="tname"/><result column="TSEX" property="tsex"/> <result column="TBIRTHDAY" property="tBirthday"/> <result column="PROF" property="prof"/> <result column="DEPART" property="depart"/ </association> </resultMap <parameterMap type="Student01" id="baseParameterMap"> <parameter property="s_no" javaType="java.lang.String"/> <parameter property="s_name" javaType="java.lang.String"/> <parameter property="s_sex" javaType="java.lang.String"/> <parameter property="s_birthday" javaType="java.util.Date"/> <parameter property="s_class" javaType="java.lang.String"/> </parameterMap> <!-- 查询 --> <!-- 使用占位符：#｛｝表示一个占位符 --> <select id="getInfo" resultType="Student"> select * from student where SNO = 108 </select> <select id="getInfoById" resultType="Student"> select * from student where SNO = #{sno} and SBIRTHDAY = #{sBirthday} </select> <select id="getInfo01" resultMap="baseResultMap"> select * from student where SNO = 108 </select> <select id="getInfoById01" resultMap="baseResultMap" parameterMap="baseParameterMap"> select * from student where SNO = #{s_no} and SBIRTHDAY = #{s_birthday} </select> <!-- 测试if标签 --> <select id="dySelectIf" resultType="Student" parameterType="Student" > select * from student where 1=1 <if test="sno != null"> and sno = #{sno} </if> <if test="sBirthday != null"> and sBirthday = #{sBirthday} </if> </select><!-- 测试 choose标签--> <select id="dySelectChoose" resultType="Student" parameterType="Student"> select * from student where 1=1 <choose> <when test="sno != null"> and sno = #{sno} </when> <when test="sBirthday != null"> and sBirthday = #{sBirthday} </when> </choose> </select> <!-- 测试 where标签--> <select id="dySelectWhere" resultType="Student" parameterType="Student"> select * from student <where> <if test="sno != null"> and sno = #{sno} </if> <if test="sBirthday != null"> and sBirthday = #{sBirthday} </if> </where> </select> <!-- 测试update --> <update id="dyUpate" parameterType="Student"> update student <set> <if test="sno != null"> sBirthday = #{sBirthday} </if> </set> <where> <if test="sno != null"> and sno = #{sno} </if> </where> </update><!-- 测试forEach标签 --> <select id="dyForEach" parameterType="java.util.List" resultType="Student"> select * from student where sno in <foreach collection="list" index="index" item="item" open="(" close=")" separator=","> #{item} </foreach> </select> <!-- 测试forEachMap标签 --> <select id="dyForEachMap" parameterType="java.util.Map" resultType="Student"> select * from student where sno in <foreach collection="ids" index="index" item="item" open="(" close=")" separator=","> #{item} </foreach> </select> <!-- 测试trim标签 --> <select id="dyTrim" resultType="Student" parameterType="Student"> select * from student <trim prefix="where" prefixOverrides="and | or"> <if test="sno != null"> and sno = #{sno} </if> <if test="sBirthday != null "> and sBirthday = #{sBirthday} </if> </trim> </select> <!-- 测试多对一关系映射 --> <select id="getStudent" resultMap="Student" parameterType="java.lang.String"> select * from student a,teacher b where a.tno = b.tno and a.sno = #{sno} </select></mapper>6.测试MyBatis
package com.zhiliaotang.mybatis.test;import java.io.IOException;import java.io.Reader;import java.text.ParseException;import java.text.SimpleDateFormat;import java.util.ArrayList;import java.util.Date;import java.util.HashMap;import java.util.List;import java.util.Map;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.zhiliaotang.mybatis.dao.StudentDao;import com.zhiliaotang.mybatis.model.Student;import com.zhiliaotang.mybatis.model.Student01;import com.zhiliaotang.mybatis.model.Teacher;public class MyBatisTest { //加载配置文件 private static SqlSessionFactory sqlSessionFactory; private static Reader reader; static { try { reader = Resources.getResourceAsReader("config.xml"); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader); } //查询id为108的信息 @Test public void m01() { //CRUD //获取SqlSession对象//执行映射文件中SQL语句 //返回结果 SqlSession sqlSession = sqlSessionFactory.openSession(); String sql = "com.zhiliaotang.mybatis.mapper.StudentMapper.getInfo"; Student student = sqlSession.selectOne(sql); System.out.println(student.getSno() +" "+student.getSname()+" "+student.getSsex()+" "+student.getsBirthday()+" "+student.getClas()); sqlSession.close(); } //条件查询 @Test public void m02() { SqlSession sqlSession = sqlSessionFactory.openSession(); String sql = "com.zhiliaotang.mybatis.mapper.StudentMapper.getInfoById"; Student student = sqlSession.selectOne(sql, 108); System.out.println(student.getSno() +" "+student.getSname()+" "+student.getSsex()+" "+student.getsBirthday()+" "+student.getClas()); sqlSession.close(); } //数据类型不匹配的情况（时间类型） @Test public void m03() throws ParseException{ SqlSession sqlSession = sqlSessionFactory.openSession(); String s = "1977-09-01 00:00:00"; SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); String sql = "com.zhiliaotang.mybatis.mapper.StudentMapper.getInfoById"; Student student = sqlSession.selectOne(sql, new Student("108", sdf.parse(s))); System.out.println(student.getSno() +" "+student.getSname()+" "+student.getSsex()+" "+student.getsBirthday()+" "+student.getClas()); sqlSession.close(); } //字段名与表名不相同时的情况处理 @Test public void m04() { SqlSession sqlSession = sqlSessionFactory.openSession(); String sql = "com.zhiliaotang.mybatis.mapper.StudentMapper.getInfo01"; Student01 student01 = sqlSession.selectOne(sql); System.out.println(student01.getS_no()+" "+student01.getS_name()+" "+student01.getS_sex()+" "+student01.getS_birthday()+" "+student01.getS_class()); sqlSession.close(); }@Test public void m05() throws ParseException { SqlSession sqlSession = sqlSessionFactory.openSession(); String s = "1977-09-01 00:00:00"; SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); String sql = "com.zhiliaotang.mybatis.mapper.StudentMapper.getInfoById01"; Student01 student01 = sqlSession.selectOne(sql, new Student01("108",sdf.parse(s))); System.out.println(student01.getS_no()+" "+student01.getS_name()+" "+student01.getS_sex()+" "+student01.getS_birthday()+" "+student01.getS_class()); sqlSession.close(); } /*@Test public void m06() { SqlSession sqlSession = sqlSessionFactory.openSession(); Date date = new Date(); String sql = "com.zhiliaotang.mybatis.mapper.StudentMapper.insertStudent"; Student01 student01 = sqlSession.selectOne(sql,new Student01("110","豆豆","女",date ,"7201")); System.out.println(student01.getS_no()+" "+student01.getS_name()+" "+student01.getS_sex()+" "+student01.getS_birthday()+" "+student01.getS_class()); sqlSession.commit(); sqlSession.close(); }*/ //测试if @Test public void m07() throws ParseException { SqlSession sqlSession = sqlSessionFactory.openSession(); String s = "1977-09-01 00:00:00"; SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); String sql = "com.zhiliaotang.mybatis.mapper.StudentMapper.dySelectIf"; Student student = sqlSession.selectOne(sql,new Student("108",sdf.parse(s))); System.out.println(student.getSno()+" "+student.getsBirthday()); sqlSession.close(); } //测试choose @Test public void m08() throws ParseException { SqlSession sqlSession = sqlSessionFactory.openSession(); String s = "1977-09-01 00:00:00"; SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");String sql = "com.zhiliaotang.mybatis.mapper.StudentMapper.dySelectChoose"; Student student = sqlSession.selectOne(sql,new Student("108",sdf.parse(s))); System.out.println(student.getSno()+" "+student.getsBirthday()); sqlSession.close(); } //测试where @Test public void m09() throws ParseException { SqlSession sqlSession = sqlSessionFactory.openSession(); String s = "1977-09-01 00:00:00"; SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); String sql = "com.zhiliaotang.mybatis.mapper.StudentMapper.dySelectWhere"; Student student = sqlSession.selectOne(sql,new Student("108",sdf.parse(s))); System.out.println(student.getSno()+" "+student.getsBirthday()); sqlSession.close(); } //测试update @Test public void m10() throws ParseException { SqlSession sqlSession = sqlSessionFactory.openSession(); String s = "1977-09-01 10:20:30"; SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); String sql = "com.zhiliaotang.mybatis.mapper.StudentMapper.dyUpate"; sqlSession.update(sql, new Student("108",sdf.parse(s))); sqlSession.commit(); sqlSession.close(); } //测试forEach @Test public void m11() { SqlSession sqlSession = sqlSessionFactory.openSession(); String sql = "com.zhiliaotang.mybatis.mapper.StudentMapper.dyForEach"; List<String> list = new ArrayList<>(); list.add("107"); list.add("108"); List<Student> listStudent = sqlSession.selectList(sql, list); for(Student stu : listStudent) { System.out.println(stu.getSno()+" "+stu.getsBirthday()); } sqlSession.close(); } //测试trim @Test public void m13() throws ParseException { SqlSession sqlSession = sqlSessionFactory.openSession(); String sql = "com.zhiliaotang.mybatis.mapper.StudentMapper.dyTrim"; String s = "1977-09-01 10:20:30"; SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); Student student = sqlSession.selectOne(sql,new Student("108",sdf.parse(s))); System.out.println(student.getSno()+" "+student.getsBirthday()); sqlSession.close(); } //测试多对一关系映射 @Test public void m14() { SqlSession sqlSession = sqlSessionFactory.openSession(); String sql = "com.zhiliaotang.mybatis.mapper.StudentMapper.getStudent"; Student student = sqlSession.selectOne(sql,"108"); //mybatis返回是一个学生的实体对象 //如果要显示学生对应老师名称，按照对象的方式去寻找老师的对象，再去获取老师的属性 //多对一关系，子表对应父表的关系 Teacher teacher = student.getTeacher(); System.out.println(student.getSname()+" "+teacher.getTname()); sqlSession.close(); } //测试一对多关系映射 @Test public void m15() { SqlSession sqlSession = sqlSessionFactory.openSession(); String sql = "com.zhiliaotang.mybatis.mapper.TeacherMapper.getTeacher"; //mybatis返回的是一个老师的实体对象 //如果显示一个老师下面的多个学生，先找老师对象，然后找学生对象 Teacher teacher = sqlSession.selectOne(sql,"804"); List<Student> student = teacher.getStudent(); for(Student s : student) { System.out.println(teacher.getTname()+" "+s.getSname()); } sqlSession.close(); }//测试使用Map快速多表查询 @Test public void m16() { SqlSession sqlSession = sqlSessionFactory.openSession(); String sql = "com.zhiliaotang.mybatis.mapper.TeacherMapper.getTeacherMap"; List<Map> list = sqlSession.selectList(sql, "804"); for(Map map : list) { System.out.println(map.get("TNAME")+" "+map.get("SNAME")); } sqlSession.close(); } //接口注释测试 @Test public void m17() { SqlSession sqlSession = sqlSessionFactory.openSession(); //初始化接口对象 //调用接口中方法就是去执行某一个数据库的操作 StudentDao studentDao = sqlSession.getMapper(StudentDao.class); Student student = studentDao.getStudent("108"); System.out.println(student.getSno()+" "+student.getSname()); sqlSession.close(); }}阅读全文
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