JPA（四）之实体关系一对一

1.背景介绍：对于每个人和身份证号的关系就是一对一

2.persistence.xml和前面完全一样

3.实体bean

IdCard.java

package com.sinoi.bean;

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

//被维护端
@Entity
public class IdCard {
	@Id @GeneratedValue
	private Integer id;
	@Column(length=18, nullable=false)
	private String cardNo;
	@OneToOne(mappedBy="idCard", cascade={CascadeType.MERGE, CascadeType.REFRESH, CascadeType.PERSIST},
			optional=false)
	private Person person;
	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public String getCardNo() {
		return cardNo;
	}
	public void setCardNo(String cardNo) {
		this.cardNo = cardNo;
	}
	public Person getPerson() {
		return person;
	}
	public void setPerson(Person person) {
		this.person = person;
	}
	
}

 

Person.java

package com.sinoi.bean;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToOne;

//维护端
@Entity
public class Person {
	@Id @GeneratedValue
	private Integer id;
	@Column(length=10, nullable=false)
	private String name;
	@OneToOne(cascade={CascadeType.ALL}, optional=false)
	@JoinColumn(name="per_id_for")
	private IdCard idCard;
	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public IdCard getIdCard() {
		return idCard;
	}
	public void setIdCard(IdCard idCard) {
		this.idCard = idCard;
	}
	
}

 

4.测试

 

 

package junit.test;

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;

import org.junit.Test;

import com.sinoi.bean.IdCard;
import com.sinoi.bean.Person;


public class UnitTest {
	@Test
	public void save() {
		EntityManagerFactory factory = Persistence.createEntityManagerFactory("unitname");
		EntityManager manager = factory.createEntityManager();
		manager.getTransaction().begin();
		
		IdCard idCard = new IdCard();
		idCard.setCardNo("3408281990qqqqwwww");
		Person person = new Person();
		person.setName("bean");
		idCard.setPerson(person);
		person.setIdCard(idCard);
		
		manager.persist(person);//为什么manager.persiste(idCard)会出现错误
		manager.getTransaction().commit();
		manager.close();
		factory.close();
	}
}