前期准备

开发环境的搭建工作完全可以参考jpa小例子。 该程序使用人和身份证进行说明

代码

下面是user班级的类

package com.nova.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;

@Entity
public class User {
    @Id
    @GeneratedValue
    private Integer id;
    @Column(length = 20, nullable = false)
    private String name;
    @Column(length = 5)
    private Gender gender = Gender.MAN;

    @OneToOne(optional = false, cascade = { CascadeType.ALL })
    @JoinColumn(name = "id_card")
    private IDCard idCard;

    public IDCard getIdCard() {
        return idCard;
    }

    public void setIdCard(IDCard idCard) {
        this.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 Gender getGender() {
        return gender;
    }

    public void setGender(Gender gender) {
        this.gender = gender;
    }
}

下面是IDCard类

package com.nova.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;

@Entity
public class IDCard {
    @Id
    @GeneratedValue
    private Integer id;
    @Column(length = 20)
    private String cardId;

    @OneToOne(cascade = { CascadeType.MERGE, CascadeType.REFRESH }, mappedBy = "idCard")
    private User user;

    public User getUser() {
        return user;
    }

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

    public Integer getId() {
        return id;
    }

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

    public String getCardId() {
        return cardId;
    }

    public void setCardId(String cardId) {
        this.cardId = cardId;
    }
}

下面是单元测试

package com.nova.bean;

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

import org.junit.Test;

public class OneToOneTest {
    @Test
    public void init() {
        // 可以验证生成表是否正确
        EntityManagerFactory factory = Persistence
                .createEntityManagerFactory("myJpa");
        factory.close();
    }

    @Test
    public void create() {
        EntityManagerFactory emf = Persistence
                .createEntityManagerFactory("myJpa");
        EntityManager em = emf.createEntityManager();
        em.getTransaction().begin();

        User user = new User();
        user.setName("小小");
        user.setGender(Gender.WOMAN);

        IDCard idcard = new IDCard();
        idcard.setCardId("1234567890");

        user.setIdCard(idcard);

        em.persist(user);

        em.getTransaction().commit();
        em.close();
        emf.close();
    }
}