Mybatis（5）：使用sql映射文件，将返回结果封装为ResulMap

四部曲：

1.写接口  +  2.写映射sql  + 3.把mapper注册到mybatis的配置文件  + 4.写单元测试和运行

      今天通过使用Mybatis框架·，将MySQL查询得到的数据封装为ResulMap，并映射到实体类User.java。这个过程是通过设置<select ></select >的resultMap属性为<resultMap></resultMap>的id，从而调用了它。

下面是具体的代码：

（1）首先新建一个User.java文件，作为这次的实体类，注意一定要有setter方法（mybatis通过setter访问器进行读取）：

package com.smbms.entities;

import java.util.Date;
import java.util.List;

public class User {
private Integer id;
private String userCode;
private String userName;
private String userPassword;
private Integer gender;
private Date birthday;
private String phone;
private String address ;
private Integer userRole;
private Integer createdBy;
private Date creationDate;
private Integer modifyBy;
private Date modifyDate;

public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getUserCode() {
return userCode;
}
public void setUserCode(String userCode) {
this.userCode = userCode;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getUserPassword() {
return userPassword;
}
public void setUserPassword(String userPassword) {
this.userPassword = userPassword;
}
public Integer getGender() {
return gender;
}
public void setGender(Integer gender) {
this.gender = gender;
}
public Date getBirthday() {
return birthday;
}
public void setBirthday(Date birthday) {
this.birthday = birthday;
}
public String getPhone() {
return phone;
}
public void setPhone(String phone) {
this.phone = phone;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
public Integer getUserRole() {
return userRole;
}
public void setUserRole(Integer userRole) {
this.userRole = userRole;
}
public Integer getCreatedBy() {
return createdBy;
}
public void setCreatedBy(Integer createdBy) {
this.createdBy = createdBy;
}
public Date getCreationDate() {
return creationDate;
}
public void setCreationDate(Date creationDate) {
this.creationDate = creationDate;
}
public Integer getModifyBy() {
return modifyBy;
}
public void setModifyBy(Integer modifyBy) {
this.modifyBy = modifyBy;
}
public Date getModifyDate() {
return modifyDate;
}
public void setModifyDate(Date modifyDate) {
this.modifyDate = modifyDate;
}
public User(Integer id, String userCode, String userName, String userPassword, Integer gender, Date birthday,
String phone, String address, Integer userRole, Integer createdBy, Date creationDate, Integer modifyBy,
Date modifyDate) {
super();
this.id = id;
this.userCode = userCode;
this.userName = userName;
this.userPassword = userPassword;
this.gender = gender;
this.birthday = birthday;
this.phone = phone;
this.address = address;
this.userRole = userRole;
this.createdBy = createdBy;
this.creationDate = creationDate;
this.modifyBy = modifyBy;
this.modifyDate = modifyDate;
}
public User() {
super();
// TODO 自动生成的构造函数存根
}
@Override
public String toString() {
return "User [id=" + id + ", userCode=" + userCode + ", userName=" + userName + ", userPassword=" + userPassword
+ ", gender=" + gender + ", birthday=" + birthday + ", phone=" + phone + ", address=" + address
+ ", userRole=" + userRole + ", createdBy=" + createdBy + ", creationDate=" + creationDate
+ ", modifyBy=" + modifyBy + ", modifyDate=" + modifyDate + "]";
}

}

（2）然后，新建一个接口类 UserMapper.java，定义一个新的方法 public List<User> getUserList(User user) ;：

package com.smbms.dao;

import java.util.List;
import java.util.Map;

import org.apache.ibatis.annotations.Param;

import com.smbms.entities.User;

public interface UserMapper {

public List<User> getUserList(User user);

}

（3）然后，新建一个UserMapper.xml文件，用来编写sql映射语句：
【业务模型传递参数到sql执行查询操作：parameterType = "com.smbms.entities.User“；】

【数据库返回的结果到业务模型，调用了 resultMap：resultMap="userlist" 】

<?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">
<mapper namespace="com.smbms.dao.UserMapper">
<select id="getUserList" resultMap="userlist" parameterType="com.smbms.entities.User">
select u.*,r.rolename from  smbms_user u ,smbms_role r
where u.username like CONCAT('%',#{username},'%')
and u.userRole = #{userRole} and u.userRole = r.id
</select>
<resultMap type="com.smbms.entities.User" id="userlist">
<result property="id" column="id"/>
<result property="userCode" column="userCode"/>
<result property="userName" column="username"/>
<result property="phone" column="phone"/>
<result property="birthday" column="birthday"/>
<result property="gender" column="gender"/>
<result property="userRole" column="userRole"/>
<result property="userRoleName" column="userRoleName"/>
</resultMap>
</mapper>

（4）编写测试用例，导入JUnit4.jar后，可以新建测试用例UserTest.java：

package com.smbms.entities;

import java.io.IOException;
import java.io.InputStream;
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.smbms.dao.ProviderMapper;
import com.smbms.dao.UserMapper;

public class UserTest {

public SqlSession getSqlSession() throws IOException{
String resource = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
SqlSessionFactory build = new SqlSessionFactoryBuilder().build(inputStream);
SqlSession openSession = build.openSession();
return openSession;
}

//使用resultMap完成查询结果的展现
@Test
public void test06() throws IOException{
User user = new User();
user.setUserName("mmb");
user.setUserRole(110);
SqlSession session = getSqlSession();
UserMapper mapper = session.getMapper(UserMapper.class);
List<User> userByUsername = mapper.getUserList(user);
for(User user1:userByUsername){
System.out.println("+*+:" +user
4000
1.getUserRoleName()+user1.getPhone()+user1.getUserCode()+user1.getUserName()+user1.getUserRole());
}
}

}

由此完成一个小Demo。

注意之处：

（1）ResulMap 具有两个元素：type 和 id ，type对应结果映射的实体类，id 是Map的唯一标识；

（2）result 是 ResulMap 下的标签元素，具有两个属性：property 和 column， column 对应于数据库的列名，property 对应于实体类定义的属性变量。