Mybatis 入门之resultMap与resultType讲解实例

resultMap：适合使用返回值是自定义实体类的情况resultType：适合使用返回值得数据类型是非自定义的，即jdk的提供的类型resultMap ： type：映射实体类的数据类型id：resultMap的唯一标识column:库表的字段名property：实体类里的属性名配置映射文件：<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd"><!-- namespace:当前库表映射文件的命名空间，唯一的不能重复 --><mapper namespace="com.hao947.sql.mapper.PersonMapper"><!-- type:映射实体类的数据类型 id：resultMap的唯一标识 --><resultMap type="person" id="BaseResultMap"><!-- column:库表的字段名 property:实体类里的属性名 --><id column="person_id" property="personId" /><result column="name" property="name" /><result column="gender" property="gender" /><result column="person_addr" property="personAddr" /><result column="birthday" property="birthday" /></resultMap><!--id:当前sql的唯一标识parameterType：输入参数的数据类型resultType：返回值的数据类型#{}:用来接受参数的，如果是传递一个参数#{id}内容任意，如果是多个参数就有一定的规则,采用的是预编译的形式select* from person p where p.id = ? ，安全性很高 --><!-- sql语句返回值类型使用resultMap --><select id="selectPersonById" parameterType="java.lang.Integer"resultMap="BaseResultMap">select * from person p where p.person_id = #{id}</select><!-- resultMap:适合使用返回值是自定义实体类的情况resultType：适合使用返回值的数据类型是非自定义的，即jdk的提供的类型 --><select id="selectPersonCount" resultType="java.lang.Integer">select count(*) fromperson</select><select id="selectPersonByIdWithMap" parameterType="java.lang.Integer"resultType="java.util.Map">select * from person p where p.person_id= #{id}</select></mapper>

实体类Person.java

<pre name="code" class="java">package com.hao947.model;import java.util.Date;public class Person {private Integer personId;private String name;private Integer gender;private String personAddr;private Date birthday;@Overridepublic String toString() {return "Person [personId=" + personId + ", name=" + name + ", gender="+ gender + ", personAddr=" + personAddr + ", birthday="+ birthday + "]";}}

测试类

public class PersonTest {SqlSessionFactory sqlSessionFactory;@Beforepublic void setUp() throws Exception {// 读取资源流InputStream in = Resources.getResourceAsStream("sqlMapConfig.xml");// 初始化session工厂sqlSessionFactory = new SqlSessionFactoryBuilder().build(in);}@Testpublic void selectPersonById() {// 创建一个sqlsessionSqlSession session = sqlSessionFactory.openSession();try {Person p = session.selectOne("com.hao947.sql.mapper.PersonMapper.selectPersonById", 1);System.out.println(p);} finally {session.close();}}@Testpublic void selectPersonCount() {// 创建一个sqlsessionSqlSession session = sqlSessionFactory.openSession();try {Integer p = session.selectOne("com.hao947.sql.mapper.PersonMapper.selectPersonCount");System.out.println(p);} finally {session.close();}}@Testpublic void selectPersonByIdWithMap() {// 创建一个sqlsessionSqlSession session = sqlSessionFactory.openSession();try {Map<String ,Object> map = session.selectOne("com.hao947.sql.mapper.PersonMapper.selectPersonByIdWithMap",1);System.out.println(map);} finally {session.close();}}}