hibernate-annotations——@OneToOne-优快云博客

本文链接：https://blog.youkuaiyun.com/iteye_15162/article/details/81922378

本文介绍了一对一关联关系在Hibernate中的两种实现方式：共享主键和外键映射。通过两个具体的例子，详细展示了如何使用Java注解配置这些关联关系，并提供了完整的实体类代码示例。

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1.OneToOne共享主键

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

/**
 * @author lan 2010-8-26
 * 主表
 */
@Entity
public class Body {

    private Integer id;
    private Heart heart;
    private Integer age;

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

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

    @OneToOne(cascade = CascadeType.ALL)
    @PrimaryKeyJoinColumn
    public Heart getHeart() {
        return heart;
    }

    public void setHeart(Heart heart) {
        this.heart = heart;
    }

}

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

import org.hibernate.annotations.GenericGenerator;
import org.hibernate.annotations.Parameter;

/**
 * @author lan 2010-8-26
 * 从表
 */
@Entity
public class Heart {

    private Integer id;
    private Body body;
    private Double weight;

    @Id
    @GenericGenerator(name = "fk", strategy = "foreign", parameters = @Parameter(name = "property", value = "body"))
    @GeneratedValue(generator = "fk")
    public Integer getId() {
        return id;
    }

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

    @OneToOne(optional=false)
    @PrimaryKeyJoinColumn(name="body_id")
    public Body getBody() {
        return body;
    }

    public void setBody(Body body) {
        this.body = body;
    }

}

2.OneToOne外键

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

/**
 * @author lan
 * 2010-8-26
 * 主表
 */
@Entity
public class Passport {
    private Integer id;
    private String name;
    private Customer owner;

    @Id
    @GeneratedValue
    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;
    }

    @OneToOne(mappedBy="passport", cascade=CascadeType.ALL)
    public Customer getOwner() {
        return owner;
    }

    public void setOwner(Customer owner) {
        this.owner = owner;
    } 
}

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

/**
 * @author lan
 * 2010-8-26
 * 从表
 */
@Entity
public class Customer {
    
    private Integer id;

    private Passport passport;

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

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

    @OneToOne
    @JoinColumn(name="passport_id")
    public Passport getPassport() {
        return passport;
    }

    public void setPassport(Passport passport) {
        this.passport = passport;
    }
    
}