OneToOne annotation 双向关联

 

package com.hibernate.entity;

import java.io.Serializable;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToOne;

@Entity
public class Husband implements Serializable {

/**
*
*/
private static final long serialVersionUID = 2476364405175138004L;

private int id;

private String name;

private Wife wife;

@Id
@GeneratedValue
public int getId() {
return id;
}

public String getName() {
return name;
}

@OneToOne
public Wife getWife() {
return wife;
}

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

public void setName(String name) {
this.name = name;
}

public void setWife(Wife wife) {
this.wife = wife;
}

}

 

 

package com.hibernate.entity;

import java.io.Serializable;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToOne;

@Entity
public class Wife implements Serializable {

/**
*
*/
private static final long serialVersionUID = 5270130768836331730L;

private int id;

private String name;

private Husband husband;

@Id
@GeneratedValue
public int getId() {
return id;
}

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

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

@OneToOne(mappedBy="wife")
public Husband getHusband() {
return husband;
}

public void setHusband(Husband husband) {
this.husband = husband;
}

}

 
 

 

注意
：Wife类的getHusband()上用了mappedBy"wife"

这个意思是说，我这里的OneToOne就不用管了，只用Husband里的getWife()上的OneToOne关系

生成的表为Husband参考Wife，有了wifeid，才能有Husband

Husband为这个关系的拥有者

 

如果Wife类的getHusband()只有@OneToOne，没有mappedBy，那么生成的两张表都会有对方的外键，造成外键冗余。