@MappedSuperclass的用法

@MappedSuperclass的用法
用在实体的继承过程中的父类上；

父类Cat

package com.xj.model;

import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.MappedSuperclass;

@MappedSuperclass
public class Cat {
	private Long id;
	private String name;
	@Id
	@GeneratedValue
	public Long getId() {
		return id;
	}
	public void setId(Long id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
}

子类1 BeijingCat

package com.xj.model;

import javax.persistence.Entity;
import javax.persistence.Table;

@Entity
@Table(name="t_beijingcat")
public class BeijingCat extends Cat {
	private String beijing;

	public String getBeijing() {
		return beijing;
	}

	public void setBeijing(String beijing) {
		this.beijing = beijing;
	}

}

子类2 ShanghaiCat

package com.xj.model;

import javax.persistence.Entity;
import javax.persistence.Table;

@Entity
@Table(name="t_shanghaiCat")
public class ShanghaiCat extends Cat {
	private String shanghai;

	public String getShanghai() {
		return shanghai;
	}

	public void setShanghai(String shanghai) {
		this.shanghai = shanghai;
	}
}

结果生成 两张表t_beijingcat、 t_shanghaicat

如果不用@MappedSuperclass 而用@Entity替换的话，只会生成一张cat表，字段有：id，name，shanghaicat，bejingcat

评论

1 楼 MySpringDay 2014-06-03  

简洁易懂