Mybatis一对一结果映射

目录结构

创建数据库相应的表

一个账户对应一个用户
accout

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

user

CREATE TABLE `user` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `username` varchar(20) DEFAULT NULL,
  `PASSWORD` varchar(20) DEFAULT NULL,
  `sex` varchar(2) DEFAULT NULL,
  `birthday` date DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=47 DEFAULT CHARSET=utf8;

domain 实体类

Account

package com.william.domain;

/**
 * @author ：lijunxuan
 * @date ：Created in 2020/2/2  20:35
 * @description ：
 * @version: 1.0
 */
public class Account {
    Integer aid;
    String accountname;
    Float money;
    Integer userId;
    User user;

    @Override
    public String toString() {
        return "Account{" +
                "aid=" + aid +
                ", accountname='" + accountname + '\'' +
                ", money=" + money +
                ", userId=" + userId +
                ", user=" + user +
                '}';
    }

    public Integer getAid() {
        return aid;
    }

    public void setAid(Integer aid) {
        this.aid = aid;
    }

    public String getAccountname() {
        return accountname;
    }

    public void setAccountname(String accountname) {
        this.accountname = accountname;
    }

    public Float getMoney() {
        return money;
    }

    public void setMoney(Float money) {
        this.money = money;
    }

    public Integer getUserId() {
        return userId;
    }

    public void setUserId(Integer userId) {
        this.userId = userId;
    }

    public User getUser() {
        return user;
    }

    public void setUser(User user) {
        this.user = user;
    }
}

User

package com.william.domain;

/**
 * @author ：lijunxuan
 * @date ：Created in 2020/2/2  20:37
 * @description ：
 * @version: 1.0
 */
public class User {
    Integer id;
    String username;
    String PASSWORD;
    String sex;
    String birthday;

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", PASSWORD='" + PASSWORD + '\'' +
                ", sex='" + sex + '\'' +
                ", birthday='" + birthday + '\'' +
                '}';
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPASSWORD() {
        return PASSWORD;
    }

    public void setPASSWORD(String PASSWORD) {
        this.PASSWORD = PASSWORD;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public String getBirthday() {
        return birthday;
    }

    public void setBirthday(String birthday) {
        this.birthday = birthday;
    }
}

mapper Dao

package com.william.mapper;

import com.william.domain.Account;
import com.william.domain.QueryVo;
import com.william.domain.Usert;
import org.apache.ibatis.annotations.Param;

import java.util.HashMap;
import java.util.List;

public interface Usermapper {
    List<Account> findByhaha();
}

mapper.xml 映射文件

<?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.william.mapper.Usermapper">
    <resultMap id="accoutMap" type="account">
        <id property="aid" column="aid"></id>
        <result property="accountname" column="accountname"></result>
        <result property="money" column="money"></result>
        <result property="userId" column="userId"></result>
        <result property="user.id" column="id"></result>
        <result property="user.username" column="username"></result>
        <result property="user.PASSWORD" column="PASSWORD"></result>
        <result property="user.sex" column="sex"></result>
        <result property="user.birthday" column="birthday"></result>
    </resultMap>
    <select id="findByhaha" resultMap="accoutMap">
        select * from account a ,user u where a.userId=u.id;
    </select>
</mapper>

配置文件

1.db.properties 数据库配置文件

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

2.log4j.properties日志文件

# Set root category priority to INFO and its only appender to CONSOLE.
#log4j.rootCategory=INFO, CONSOLE            debug   info   warn error fatal
log4j.rootCategory=debug, CONSOLE, LOGFILE, info

# Set the enterprise logger category to FATAL and its only appender to CONSOLE.
log4j.logger.org.apache.axis.enterprise=FATAL, CONSOLE

# CONSOLE is set to be a ConsoleAppender using a PatternLayout.
log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender
log4j.appender.CONSOLE.layout=org.apache.log4j.PatternLayout
log4j.appender.CONSOLE.layout.ConversionPattern=%d{ISO8601} %-6r [%15.15t] %-5p %30.30c %x - %m\n

# LOGFILE is set to be a File appender using a PatternLayout.
log4j.appender.LOGFILE=org.apache.log4j.FileAppender
log4j.appender.LOGFILE.File=d:\axis.log
log4j.appender.LOGFILE.Append=true
log4j.appender.LOGFILE.layout=org.apache.log4j.PatternLayout
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

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <properties resource="db.properties"></properties>
    <typeAliases>
        <package name="com.william.domain"></package>
    </typeAliases>
    <environments default="develoment">
        <environment id="develoment">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driver}"></property>
                <property name="url" value="${jdbc.url}"></property>
                <property name="username" value="${jdbc.user}"></property>
                <property name="password" value="${jdbc.password}"></property>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <!--<mapper resource="com/william/Mapper.xml"></mapper>-->
        <package name="com.william.mapper"></package>
    </mappers>
</configuration>

test测试类

package com.william.test;

import com.william.domain.Account;
import com.william.domain.QueryVo;
import com.william.domain.Usert;
import com.william.mapper.Usermapper;
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 java.io.IOException;
import java.util.HashMap;
import java.util.List;

/**
 * @author ：lijunxuan
 * @date ：Created in 2020/2/2  13:28
 * @description ：
 * @version: 1.0
 */
public class TestMyBatis {
    /**
     * 查询所有的账户相同的
     */
    @Test
    public void selectAll(){
        try {
            SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("Mybatis-config.xml"));
            SqlSession sqlSession = sqlSessionFactory.openSession(true);
            Usermapper mapper = sqlSession.getMapper(Usermapper.class);
            List<Account> list = mapper.findByhaha();
            for (Account account : list) {
                System.out.println(account.getAid());
                System.out.println(account);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

测试结果

来源：CSDN

作者：L-李俊漩

链接：https://blog.csdn.net/sinat_39179993/article/details/104149485