第五简单mybatis resulstMap-helloworld及动态sql

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步骤：

Jar包导入，生成数据库表，创建与src同级资源目录config,test目录(注意，config,test均为资源目录)

1.创建实体类：

User.java

package com.xiangshuai.mybatis.pojo;

import java.util.Date;

public classUser {

private int id;

private Integersex;

private Datebirthday;

private Stringaddress;

private Stringusername;

public User(Integersex, Date birthday, Stringaddress, String username) {

super();

this.sex =sex;

this.birthday =birthday;

this.address =address;

this.username =username;

}

public User() {

super();

// TODO Auto-generated constructor stub

}

public String getUsername() {

returnusername;

}

public void setUsername(String username) {

this.username =username;

}

public int getId() {

returnid;

}

public void setId(intid) {

this.id =id;

}

public Integer getSex() {

returnsex;

}

public void setSex(Integer sex) {

this.sex =sex;

}

public Date getBirthday() {

returnbirthday;

}

public void setBirthday(Date birthday) {

this.birthday =birthday;

}

public String getAddress() {

returnaddress;

}

public void setAddress(String address) {

this.address =address;

}

@Override

public String toString() {

return"User [id="+ id +", sex="+ sex+", birthday=" + birthday + ", address=" + address+ ", username="

+username + "]";

}

VO.java

package com.xiangshuai.mybatis.pojo;

import java.util.List;

* * 入参类型包装类

* 有 user和 user id这集合两个属性

* */

public classVO {

privateUseruser;

privateList<Integer>idList;

public List<Integer>getIdList() {

returnidList;

}

public voidsetIdList(List<Integer> idList) {

this.idList =idList;

}

public User getUser() {

returnuser;

}

public void setUser(User user) {

this.user =user;

}

2.建实体类对应的映射文件UserMapper.xml（局部xml文件）

<?xmlversion="1.0"encoding="UTF-8"?>

<!DOCTYPEmapper

PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"

"http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<!-- 注意：在mapper代理时，它具有特殊及重要的作用，在这里 namespace="com.xiangshuai.mybatis.mapper.UserMapper"

对应mapper接口UserMapper的全类名-->

<mappernamespace="com.xiangshuai.mybatis.mapper.UserMapper">

<!-- 将 select查出来的结果集映射到 resultMap标签对应的 type类型中

其实resultType也是先resultMap将映射到resultType类型中但并不需要我们自己

操作-->

<resultMaptype="com.xiangshuai.mybatis.pojo.User"id="UserRstMap">

<idcolumn="id"property="id"/>

<resultcolumn="username"property="username"/>

<resultcolumn="sex"property="sex"/>

</resultMap>

<selectid="findUserRstMap"parameterType="int"resultMap="UserRstMap">

selectid,username,birthday,sex,address fromuser where id = #{id}

</select>

<sqlid="whereClause">

<iftest="user !=null">

<iftest="user.username!= null and user.username != ''">

ANDusername LIKE '%${user.username}%'

</if>

<iftest="user.sex !=null and user.sex != ''">

ANDsex = #{user.sex}

</if>

<iftest="idList !=null">

ANDid IN

<foreachcollection="idList"item="id"open="("close=")"

separator=",">

#{id}

</foreach>

</if>

</sql>

<selectid="findUserList"parameterType="com.xiangshuai.mybatis.pojo.VO"

resultType="com.xiangshuai.mybatis.pojo.User">

SELECT* FROM user

<where>

<includerefid="whereClause"/>

</where>

</select>

<selectid="findUserCount"parameterType="com.xiangshuai.mybatis.pojo.VO"

resultType="int">

SELECTcount(*) FROM user

<where>

<includerefid="whereClause"/>

</where>

</select>

</mapper>

3.将UserMapper.xml（局部xml文件）mapper到 SqlMapConfig.xml（全局配置文件）中

<?xmlversion="1.0"encoding="UTF-8"?>

<!DOCTYPEconfiguration

PUBLIC "-//mybatis.org//DTD Config 3.0//EN"

"http://mybatis.org/dtd/mybatis-3-config.dtd">

<propertiesresource="db.properties">

</properties>

<!-- <typeAliases>

单个别名定义

<typeAliastype="com.itheima.mybatis.po.User" alias="user"/>

批量别名定义（推荐）

package：指定包名称来为该包下的po类声明别名，默认的别名就是类名（首字母大小写都可）

<packagename="com.itheima.mybatis.po" />

</typeAliases>

-->

<environmentsdefault="development">

<environmentid="development">

<transactionManagertype="JDBC"></transactionManager>

<dataSourcetype="POOLED">

<propertyname="driver"value="${db.driver}"/>

<propertyname="url"value="${db.url}"/>

<propertyname="username"value="${db.username}"/>

<propertyname="password"value="${db.password}"/>

</dataSource>

</environment>

</environments>

<mapperresource="UserMapper.xml"/>

</mappers>

</configuration>

4.严格参照UserMapper.xml 按照mapper规范创建mapper接口UserMapper.java

package com.xiangshuai.mybatis.mapper;

import java.util.List;

importcom.xiangshuai.mybatis.pojo.User;

importcom.xiangshuai.mybatis.pojo.VO;

public interface UserMapper {

public User findUserRstMap(int id);

public List<User> findUserList(VO vo);

public int findUserCount(VO vo);

}

5.测试类Demo1.java

package com.xiangshuai.test;

import java.io.IOException;

import java.io.InputStream;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

importorg.apache.ibatis.binding.MapperRegistry;

import org.apache.ibatis.io.Resources;

importorg.apache.ibatis.session.SqlSession;

importorg.apache.ibatis.session.SqlSessionFactory;

import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import org.junit.Before;

import org.junit.Test;

importcom.xiangshuai.mybatis.mapper.UserMapper;

import com.xiangshuai.mybatis.pojo.User;

import com.xiangshuai.mybatis.pojo.VO;

public class Demo1 {

/*mybatis开发方式mapper开发非mapper开始：查询，操作和hibernate很像，也是先造实体类，然后配实体类的XML映射文件，然后将实体类的XML映射文件mapper到全局映射 XML文件

SqlMapConfig.xml中去，

* */

privateSqlSessionFactory sqlSessionFactory;

@Before

publicvoid before(){

//读取配置文件

//全局配置文件的路径

Stringresource = "SqlMapConfig.xml";

InputStreaminputStream = null;

try{

inputStream= Resources.getResourceAsStream(resource);

}catch (IOException e) {

//TODO Auto-generated catch block

e.printStackTrace();

}

//创建SqlSessionFactory

sqlSessionFactory = newSqlSessionFactoryBuilder().build(inputStream);

}

//resultMap标签测试

@Test

public void findUserByUsername(){

//创建mapper对象 -- UserMapper对象

SqlSessionsqlsession = sqlSessionFactory.openSession();

UserMappermapper = sqlsession.getMapper(UserMapper.class);

//调用mapper完成增删改查方法

Useruser = mapper.findUserRstMap(1);

System.out.println(user);

}

//动态sql测试1,根据VO包装类对象动态SQL查询user

@Test

publicvoid findUserList(){

//创建mapper对象 -- UserMapper对象

SqlSessionsqlsession = sqlSessionFactory.openSession();

UserMappermapper = sqlsession.getMapper(UserMapper.class);

//调用mapper完成增删改查方法 ----在这里如果username='三'那么就只拼装username='三'的sql,其它字段不拼接，详见UserMapper.xml

Useruser = new User();user.setUsername("三");;VO vo = newVO();vo.setUser(user);

List<User>users = mapper.findUserList(vo);

System.out.println(users);

}

//动态sql测试1,根据 id 查总人数，如果id 在 idList中就查出来

@Test

publicvoid findUserCount(){

//创建mapper对象 -- UserMapper对象

SqlSessionsqlsession = sqlSessionFactory.openSession();

UserMappermapper = sqlsession.getMapper(UserMapper.class);

//调用mapper完成增删改查方法 ----在这里如果username='三'那么就只拼装username='三'的sql,其它字段不拼接，详见UserMapper.xml

List<Integer>idList=Arrays.asList(1,10,5);VO vo = new VO();vo.setIdList(idList);

intcount = mapper.findUserCount(vo);

System.out.println(count);

}

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