Mybatis一对多延迟加载实现代码解析

需求：一个用户可以有多个账户，查询用户时实现账户的延迟加载

1、用户实体类

package com.yl.bean;

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


public class User implements Serializable {
  private Integer id;//id
  private String username;//用户名
  private Date birthday;//生日
  private String sex;//性别
  private String address;//地址
  private List accountList;//用户所拥有的账户

  public User() {
  }

  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;
  }

  public List getAccountList() {
    return accountList;
  }

  public void setAccountList(List accountList) {
    this.accountList = accountList;
  }

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

2、账户实体类

package com.yl.bean;

import java.io.Serializable;


public class Account implements Serializable {
  private Integer id;//账户id
  private Integer uid;//用户id
  private Double money;//余额
  private User user;//账户所属用户

  public Account() {
  }

  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;
  }

  public User getUser() {
    return user;
  }

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

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

3、用户持久层接口

package com.yl.dao;

import com.yl.bean.User;

import java.util.List;


public interface IUserDao {

  
  List queryAll();

  
  User queryById(int id);

}

4、账户持久层接口

package com.yl.dao;

import com.yl.bean.Account;
import com.yl.bean.User;

import java.util.List;


public interface IAccountDao {

  
  List queryAll();

  
  List queryByUid(int uid);
}

5、全局配置文件

6、用户映射配置文件

  
  
    
    
    
    
    
    
    
  

  
  
    SELECT * FROM USER
  
  
  
    select * from user where id=#{id}
  

7、账户映射配置文件

  
  
    
    
    
    
    
  
  
  
  
    SELECT * FROM account
  

  
  
    select * from account where uid=#{uid}
  

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