mybatis实现一对多关系映射

sql：/*Navicat MySQL Data TransferSource Server: mysqlSource Server Version : 50549Source Host: localhost:3306Source Database: mybatisTarget Server Type...

乔治大哥

1376人浏览 · 2019-09-01 20:10:46

乔治大哥 · 2019-09-01 20:10:46 发布

sql：

/*
Navicat MySQL Data Transfer

Source Server         : mysql
Source Server Version : 50549
Source Host           : localhost:3306
Source Database       : mybatis

Target Server Type    : MYSQL
Target Server Version : 50549
File Encoding         : 65001

Date: 2019-09-01 15:40:56
*/

SET FOREIGN_KEY_CHECKS=0;

-- ----------------------------
-- Table structure for user
-- ----------------------------
DROP TABLE IF EXISTS `user`;
CREATE TABLE `user` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `username` varchar(32) NOT NULL,
  `birthday` datetime DEFAULT NULL,
  `sex` char(1) DEFAULT NULL,
  `address` varchar(256) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=46 DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of user
-- ----------------------------
INSERT INTO `user` VALUES ('41', 'lmd', '2018-02-19 00:00:00', '男', '北京');
INSERT INTO `user` VALUES ('43', 'mybatis saveuser', '2019-08-31 11:24:05', '男', '北京什刹海');
INSERT INTO `user` VALUES ('44', '卡哇伊', '2019-08-31 14:21:10', '男', '美国');
INSERT INTO `user` VALUES ('45', '卡哇伊', '2019-08-12 19:32:43', '女', '美国');






/*
Navicat MySQL Data Transfer

Source Server         : mysql
Source Server Version : 50549
Source Host           : localhost:3306
Source Database       : mybatis

Target Server Type    : MYSQL
Target Server Version : 50549
File Encoding         : 65001

Date: 2019-09-01 20:05:28
*/

SET FOREIGN_KEY_CHECKS=0;

-- ----------------------------
-- Table structure for account
-- ----------------------------
DROP TABLE IF EXISTS `account`;
CREATE TABLE `account` (
  `id` int(11) NOT NULL COMMENT '编号',
  `uid` int(11) DEFAULT NULL COMMENT '用户编号',
  `money` double(255,0) DEFAULT NULL COMMENT '金额',
  PRIMARY KEY (`id`),
  KEY `uid` (`uid`),
  CONSTRAINT `account_ibfk_1` FOREIGN KEY (`uid`) REFERENCES `user` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of account
-- ----------------------------
INSERT INTO `account` VALUES ('1', '41', '1000');
INSERT INTO `account` VALUES ('2', '44', '1000');
INSERT INTO `account` VALUES ('3', '43', '1000');

SqlMapConfig.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="jdbcConfig.properties"></properties>


    <!--使用typeAliases配置别名，它只能配置bean中类的别名-->
    <typeAliases>
        <package name="com.henu.bean"></package>
    </typeAliases>


    <!-- 配置环境 -->

    <environments default="mysql">
        <!--配置mysql的环境-->
        <environment id="mysql">
            <!--配置事务的类型-->
            <transactionManager type="JDBC"></transactionManager>
            <!--配置数据源（连接池）-->
            <dataSource type="POOLED">
                <!--配置连接数数据库的基本信息-->
                <property name="driver" value="${driver}"/>
                <property name="url" value="${url}"/>
                <property name="username" value="${username}"/>
                <property name="password" value="${password}"/>
            </dataSource>
        </environment>
    </environments>

    <!--配置映射文件的位置-->
    <mappers>
        <package name="com.henu.dao"></package>
    </mappers>

</configuration>

Bean>>>>

Account

package com.henu.bean;

import java.io.Serializable;

/**
 * @author George
 * @description
 **/
public class Account implements Serializable {

    private Integer id;
    private Integer uid;
    private double money;

    //从表实体应该包含一个主表实体的对象引用
    private User user;

    public User getUser() {
        return user;
    }

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

    public Account() {
    }

    public Account(Integer id, Integer uid, double money) {
        this.id = id;
        this.uid = uid;
        this.money = money;
    }

    public Integer getId() {
        return id;
    }

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

    public Integer getUid() {
        return uid;
    }

    public void setUid(Integer uid) {
        this.uid = uid;
    }

    public double getMoney() {
        return money;
    }

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

    @Override
    public String toString() {
        return "Account{" +
                "id=" + id +
                ", uid=" + uid +
                ", money=" + money +
                '}';
    }
}

AccountUser

package com.henu.bean;

/**
 * @author George
 * @description
 **/
public class AccountUser extends Account {

    private String username;
    private String address;

    public String getUsername() {
        return username;
    }

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

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return super.toString() + "        AccountUser{" +
                "username='" + username + '\'' +
                ", address='" + address + '\'' +
                '}';
    }
}

User

package com.henu.bean;

import java.io.Serializable;
import java.util.Date;
import java.util.List;

public class User implements Serializable {

    private Integer id;
    private String username;
    private Date birthday;
    private String sex;
    private String address;

    //一对多关系映射，主表实体应该包含从表实体的集合引用
    private List<Account> accounts;

    public List<Account> getAccount() {
        return accounts;
    }

    public void setAccount(List<Account> account) {
        this.accounts = account;
    }

    public User() {
    }

    public User(Integer id, String username, Date birthday, String sex, String address) {
        this.id = id;
        this.username = username;
        this.birthday = birthday;
        this.sex = sex;
        this.address = address;
    }

    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 Date getBirthday() {
        return birthday;
    }

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

    public String getSex() {
        return sex;
    }

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

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

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

Dao>>>>

AccountDao

package com.henu.dao;

import com.henu.bean.AccountUser;
import com.henu.bean.User;

import java.util.List;

public interface AccountDao {
    /**
     * 查询所有账户
     * @return
     */
//    List<Account> findAll();
    /**
     * 查询所有用户下的拥有账户的信息
     * @return
     */
    List<User> findAll();
    /**
     * 查询所有账户，并带有账户的用户名称和地址信息
     * @return
     */
    List<AccountUser> findAllAccount();
}

UserDao

package com.henu.dao;

import com.henu.bean.User;

import java.util.List;

public interface UserDao {
    /**
     * 查询所有
     * @return
     */
    List<User> findAll();
    /**
     * 根据userId查询用户
     * @param userId
     */
    User findUserById(Integer userId);
}

AccountDao.xml

<?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.henu.dao.AccountDao">

    <!--定义封装account和user的resultMap-->
    <resultMap id="accountUserMap" type="account">
        <id property="id" column="aid"></id>
        <result property="uid" column="uid"></result>
        <result property="money" column="money"></result>
        <!--一对一的关系映射，配置封装user的内容-->
        <association property="user" column="uid" javaType="user">
            <id property="id" column="id"></id>
            <result property="username" column="username"></result>
            <result property="birthday" column="birthday"></result>
            <result property="sex" column="sex"></result>
            <result property="address" column="address"></result>
        </association>

    </resultMap>


    <!--配置查询所有-->
    <select id="findAll" resultMap="accountUserMap">
      select u.*,a.id as aid,a.uid,a.money from account a,user u where u.id=a.uid
    </select>

    <!--配置所有账户同时含有用户名和地址信息-->
    <select id="findAllAccount" resultType="AccountUser">
      select a.*,u.username,u.address from account a,user u where u.id=a.uid
    </select>


</mapper>

UserDao.xml

<?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.henu.dao.UserDao">

    <!--定义User的ResultMap-->
    <resultMap id="userAccountMap" type="user">
        <id property="id" column="id"></id>
        <result property="username" column="username"></result>
        <result property="birthday" column="birthday"></result>
        <result property="sex" column="sex"></result>
        <result property="address" column="address"></result>
        <collection property="accounts" ofType="account">
            <id property="id" column="aid"></id>
            <result property="uid" column="uid"></result>
            <result property="money" column="money"></result>
        </collection>
    </resultMap>


    <!--配置查询所有-->
    <!--id为方法名称-->
    <select id="findAll" resultMap="userAccountMap">
      select * from user u left outer join account a on u.id=a.uid
    </select>

    <!--配置根据id查询用户-->
    <select id="findUserById" parameterType="int" resultType="User">
      select * from user where id=#{id};
    </select>

</mapper>

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