一 : ?SINGLE_TABLE繼承策略

Animal.java

import java.io.Serializable;import javax.persistence.DiscriminatorColumn; import javax.persistence.DiscriminatorValue; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.Inheritance; import javax.persistence.InheritanceType;/*** 單表繼承A* */ @Entity @Inheritance(strategy=InheritanceType.SINGLE_TABLE) // 指定為單表繼承 @DiscriminatorColumn(name="animalType") // 標識字段定義 @DiscriminatorValue("A") // 該類的標識 public class Animal {@Id@GeneratedValueprivate int id;private String name;private String sex; }
Bird.java

import javax.persistence.DiscriminatorValue; import javax.persistence.Entity;@Entity @DiscriminatorValue("B") public class Bird extends Animal{private int height; } Pig.java

import javax.persistence.DiscriminatorValue; import javax.persistence.Entity;@Entity @DiscriminatorValue("P") public class Pig extends Animal {private int weight; }
最后的表結構

二?Join映射

Animal.java

import java.io.Serializable;import javax.persistence.DiscriminatorColumn; import javax.persistence.DiscriminatorValue; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.Inheritance; import javax.persistence.InheritanceType;/*** Join映射* 父類,子類對應不同的表，子類中只存在其擴展的特殊屬性（不包含父類的屬性）* * */ @Entity @Inheritance(strategy=InheritanceType.JOINED) // 指定為單表繼承 public class Animal {@Id@GeneratedValueprivate int id;private String name;private String sex; }
Bird.java

import javax.persistence.Entity;@Entity public class Bird extends Animal {private int height; }
最后的表結構

三?TABLE_PER_CLASS

Animal.java

import java.io.Serializable;import javax.persistence.DiscriminatorColumn; import javax.persistence.DiscriminatorValue; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.Inheritance; import javax.persistence.InheritanceType;/*** TABLE_PER_CLASS策略:父類和子類對應不同的表,子類中存在所有的屬性* (包含從父類繼承下來的所有屬性)* * */ @Entity @Inheritance(strategy=InheritanceType.TABLE_PER_CLASS) public class Animal {@Id // @GeneratedValue (使用TABLE_PER_CLASS時候，不能用GeneratedValue)private int id;private String name;private String sex; }
Bird.java

import javax.persistence.Entity;@Entity public class Bird extends Animal {private int height; }

最后的表結構

創作挑戰賽新人創作獎勵來咯，堅持創作打卡瓜分現金大獎

總結

以上是生活随笔為你收集整理的(8) ebj学习: Jpa的SINGLE_TABLE,JOINED,TABLE_PER_CLASS三种继承策略的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。