Mybatis一对一结果映射

落日映苍穹つ 2023-07-03 06:04 252阅读 0赞

目录结构

目录结构

创建数据库相应的表

一个账户对应一个用户
accout

  1. CREATE TABLE `account` (
  2.   `aid` int(11) NOT NULL AUTO_INCREMENT,
  3.   `accountname` varchar(20) DEFAULT NULL,
  4.   `money` float(10,2) DEFAULT NULL,
  5.   `userId` int(11) DEFAULT NULL,
  6.   PRIMARY KEY (`aid`),
  7.   KEY `userId` (`userId`),
  8.   CONSTRAINT `account_ibfk_1` FOREIGN KEY (`userId`) REFERENCES `user` (`id`)
  9. ) ENGINE=InnoDB AUTO_INCREMENT=7 DEFAULT CHARSET=utf8;

user

  1. CREATE TABLE `user` (
  2.   `id` int(11) NOT NULL AUTO_INCREMENT,
  3.   `username` varchar(20) DEFAULT NULL,
  4.   `PASSWORD` varchar(20) DEFAULT NULL,
  5.   `sex` varchar(2) DEFAULT NULL,
  6.   `birthday` date DEFAULT NULL,
  7.   PRIMARY KEY (`id`)
  8. ) ENGINE=InnoDB AUTO_INCREMENT=47 DEFAULT CHARSET=utf8;

domain 实体类

Account

  1. package com.william.domain;
  3. /**
  4.  * @author ：lijunxuan
  5.  * @date ：Created in 2020/2/2  20:35
  6.  * @description ：
  7.  * @version: 1.0
  8.  */
  9. public class Account {
  10.     Integer aid;
  11.     String accountname;
  12.     Float money;
  13.     Integer userId;
  14.     User user;
  16.     @Override
  17.     public String toString() {
  18.         return "Account{" +
  19.                 "aid=" + aid +
  20.                 ", accountname='" + accountname + '\'' +
  21.                 ", money=" + money +
  22.                 ", userId=" + userId +
  23.                 ", user=" + user +
  24.                 '}';
  25.     }
  27.     public Integer getAid() {
  28.         return aid;
  29.     }
  31.     public void setAid(Integer aid) {
  32.         this.aid = aid;
  33.     }
  35.     public String getAccountname() {
  36.         return accountname;
  37.     }
  39.     public void setAccountname(String accountname) {
  40.         this.accountname = accountname;
  41.     }
  43.     public Float getMoney() {
  44.         return money;
  45.     }
  47.     public void setMoney(Float money) {
  48.         this.money = money;
  49.     }
  51.     public Integer getUserId() {
  52.         return userId;
  53.     }
  55.     public void setUserId(Integer userId) {
  56.         this.userId = userId;
  57.     }
  59.     public User getUser() {
  60.         return user;
  61.     }
  63.     public void setUser(User user) {
  64.         this.user = user;
  65.     }
  66. }

User

  1. package com.william.domain;
  3. /**
  4.  * @author ：lijunxuan
  5.  * @date ：Created in 2020/2/2  20:37
  6.  * @description ：
  7.  * @version: 1.0
  8.  */
  9. public class User {
  10.     Integer id;
  11.     String username;
  12.     String PASSWORD;
  13.     String sex;
  14.     String birthday;
  16.     @Override
  17.     public String toString() {
  18.         return "User{" +
  19.                 "id=" + id +
  20.                 ", username='" + username + '\'' +
  21.                 ", PASSWORD='" + PASSWORD + '\'' +
  22.                 ", sex='" + sex + '\'' +
  23.                 ", birthday='" + birthday + '\'' +
  24.                 '}';
  25.     }
  27.     public Integer getId() {
  28.         return id;
  29.     }
  31.     public void setId(Integer id) {
  32.         this.id = id;
  33.     }
  35.     public String getUsername() {
  36.         return username;
  37.     }
  39.     public void setUsername(String username) {
  40.         this.username = username;
  41.     }
  43.     public String getPASSWORD() {
  44.         return PASSWORD;
  45.     }
  47.     public void setPASSWORD(String PASSWORD) {
  48.         this.PASSWORD = PASSWORD;
  49.     }
  51.     public String getSex() {
  52.         return sex;
  53.     }
  55.     public void setSex(String sex) {
  56.         this.sex = sex;
  57.     }
  59.     public String getBirthday() {
  60.         return birthday;
  61.     }
  63.     public void setBirthday(String birthday) {
  64.         this.birthday = birthday;
  65.     }
  66. }

mapper Dao

  1. package com.william.mapper;
  3. import com.william.domain.Account;
  4. import com.william.domain.QueryVo;
  5. import com.william.domain.Usert;
  6. import org.apache.ibatis.annotations.Param;
  8. import java.util.HashMap;
  9. import java.util.List;
  11. public interface Usermapper {
  12.     List<Account> findByhaha();
  13. }

mapper.xml 映射文件

可以有两种配置方式：

方式一：

  1. <?xml version="1.0" encoding="UTF-8" ?>
  2. <!DOCTYPE mapper
  3.         PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
  4.         "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
  5. <mapper namespace="com.william.mapper.Usermapper">
  6.     <resultMap id="accoutMap" type="account">
  7.         <id property="aid" column="aid"></id>
  8.         <result property="accountname" column="accountname"></result>
  9.         <result property="money" column="money"></result>
  10.         <result property="userId" column="userId"></result>
  11.         <result property="user.id" column="id"></result>
  12.         <result property="user.username" column="username"></result>
  13.         <result property="user.PASSWORD" column="PASSWORD"></result>
  14.         <result property="user.sex" column="sex"></result>
  15.         <result property="user.birthday" column="birthday"></result>
  16.     </resultMap>
  17.     <select id="findByhaha" resultMap="accoutMap">
  18.         select * from account a ,user u where a.userId=u.id;
  19.     </select>
  20. </mapper>

方式二：使用association标签

  1. <?xml version="1.0" encoding="UTF-8" ?>
  2. <!DOCTYPE mapper
  3.         PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
  4.         "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
  5. <mapper namespace="com.william.dao.AccountDao">
  6.     <resultMap id="resultMap" type="account">
  7.         <id column="aid" property="aid"></id>
  8.         <result column="accountname" property="accountname"></result>
  9.         <result column="money" property="money"></result>
  10.         <result column="userId" property="userId"></result>
  11.         <!--association ; 关联 联想 配置一对一映射-->
  12.         <!--
  13.         property ：属性名
  14.         javaType ： 属性的类型
  15.         -->
  16.         <association property="user" javaType="user">
  17.           <id column="id" property="id"></id>
  18.           <result column="username" property="username"></result>
  19.             <result column="PASSWORD" property="PASSWORD"></result>
  20.             <result column="sex" property="sex"></result>
  21.             <result column="birthday" property="birthday"></result>
  22.         </association>
  23.     </resultMap>
  24.     <select id="findAll" resultMap="resultMap">
  25.         select * from account a,user u where a.userId=u.id;
  26.     </select>
  27. </mapper>

配置文件

1.db.properties 数据库配置文件

  1. jdbc.driver=com.mysql.jdbc.Driver
  2. jdbc.url=jdbc:mysql://localhost:3306/web02
  3. jdbc.user=root
  4. jdbc.password=root

2.log4j.properties日志文件

  1. # Set root category priority to INFO and its only appender to CONSOLE.
  2. #log4j.rootCategory=INFO, CONSOLE            debug   info   warn error fatal
  3. log4j.rootCategory=debug, CONSOLE, LOGFILE, info
  5. # Set the enterprise logger category to FATAL and its only appender to CONSOLE.
  6. log4j.logger.org.apache.axis.enterprise=FATAL, CONSOLE
  8. # CONSOLE is set to be a ConsoleAppender using a PatternLayout.
  9. log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender
  10. log4j.appender.CONSOLE.layout=org.apache.log4j.PatternLayout
  11. log4j.appender.CONSOLE.layout.ConversionPattern=%d{ISO8601} %-6r [%15.15t] %-5p %30.30c %x - %m\n
  13. # LOGFILE is set to be a File appender using a PatternLayout.
  14. log4j.appender.LOGFILE=org.apache.log4j.FileAppender
  15. log4j.appender.LOGFILE.File=d:\axis.log
  16. log4j.appender.LOGFILE.Append=true
  17. log4j.appender.LOGFILE.layout=org.apache.log4j.PatternLayout
  18. log4j.appender.LOGFILE.layout.ConversionPattern=%d{ISO8601} %-6r [%15.15t] %-5p %30.30c %x - %m\n

3.核心配置文件Mybatis-config.xml

  1. <?xml version="1.0" encoding="UTF-8" ?>
  2. <!DOCTYPE configuration
  3.         PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
  4.         "http://mybatis.org/dtd/mybatis-3-config.dtd">
  5. <configuration>
  6.     <properties resource="db.properties"></properties>
  7.     <typeAliases>
  8.         <package name="com.william.domain"></package>
  9.     </typeAliases>
  10.     <environments default="develoment">
  11.         <environment id="develoment">
  12.             <transactionManager type="JDBC"/>
  13.             <dataSource type="POOLED">
  14.                 <property name="driver" value="${jdbc.driver}"></property>
  15.                 <property name="url" value="${jdbc.url}"></property>
  16.                 <property name="username" value="${jdbc.user}"></property>
  17.                 <property name="password" value="${jdbc.password}"></property>
  18.             </dataSource>
  19.         </environment>
  20.     </environments>
  21.     <mappers>
  22.         <!--<mapper resource="com/william/Mapper.xml"></mapper>-->
  23.         <package name="com.william.mapper"></package>
  24.     </mappers>
  25. </configuration>

test测试类

  1. package com.william.test;
  3. import com.william.domain.Account;
  4. import com.william.domain.QueryVo;
  5. import com.william.domain.Usert;
  6. import com.william.mapper.Usermapper;
  7. import org.apache.ibatis.io.Resources;
  8. import org.apache.ibatis.session.SqlSession;
  9. import org.apache.ibatis.session.SqlSessionFactory;
  10. import org.apache.ibatis.session.SqlSessionFactoryBuilder;
  11. import org.junit.Test;
  13. import java.io.IOException;
  14. import java.util.HashMap;
  15. import java.util.List;
  17. /**
  18.  * @author ：lijunxuan
  19.  * @date ：Created in 2020/2/2  13:28
  20.  * @description ：
  21.  * @version: 1.0
  22.  */
  23. public class TestMyBatis {
  24.     /**
  25.      * 查询所有的账户相同的
  26.      */
  27.     @Test
  28.     public void selectAll(){
  29.         try {
  30.             SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("Mybatis-config.xml"));
  31.             SqlSession sqlSession = sqlSessionFactory.openSession(true);
  32.             Usermapper mapper = sqlSession.getMapper(Usermapper.class);
  33.             List<Account> list = mapper.findByhaha();
  34.             for (Account account : list) {
  35.                 System.out.println(account.getAid());
  36.                 System.out.println(account);
  37.             }
  38.         } catch (IOException e) {
  39.             e.printStackTrace();
  40.         }
  41.     }
  42. }

测试结果

测试结果

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