jpa/hibernate继承注解

hibernate继承映射
以下测试是在mysql中进行的。

1、单表方式
Animal.java

@Entity
@Inheritance(strategy=InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name="animalType")
@DiscriminatorValue("animal")
public class Animal {
	private int id;
	private String name;
	
	@Id
	@GeneratedValue
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
}

Cat.java

@Entity
@DiscriminatorValue("cat")
public class Cat extends Animal {

	private String catName;

	public String getCatName() {
		return catName;
	}
	public void setCatName(String catName) {
		this.catName = catName;
	}
}

Dog.java

@Entity
@DiscriminatorValue(value="dog")
public class Dog extends Animal{
	private String dogName;

	public String getDogName() {
		return dogName;
	}
	public void setDogName(String dogName) {
		this.dogName = dogName;
	}
}

TestJunit.java

	@Test
	public void testAnimal(){
		Animal t = new Animal();
		t.setName("animal");
		session.saveOrUpdate(t);
	}
	
	@Test
	public void testCat(){
		Cat t = new Cat();
		t.setName("cat");
		t.setCatName("cat");
		session.saveOrUpdate(t);
	}
	
	@Test
	public void testDog(){
		Dog t = new Dog();
		t.setName("dog");
		t.setDogName("dog");
		session.saveOrUpdate(t);
	}

对应生成的数据表是这样的
table---animal

id	name	animalType	catName	dogName
1	animal	animal	null	null
2	cat	cat	cat	null
3	dog	dog	null	dog

2、join方式
Animal.java

@Entity
@Inheritance(strategy=InheritanceType.JOINED)
public class Animal {
	private int id;
	private String name;
	
	@Id
	@GeneratedValue
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
}

Cat.java

@Entity
@PrimaryKeyJoinColumn(name="catId")
public class Cat extends Animal {

	private String catName;

	public String getCatName() {
		return catName;
	}
	public void setCatName(String catName) {
		this.catName = catName;
	}
}

Dog.java

@Entity
@PrimaryKeyJoinColumn(name="dogId")
public class Dog extends Animal{
	private String dogName;

	public String getDogName() {
		return dogName;
	}
	public void setDogName(String dogName) {
		this.dogName = dogName;
	}
}

TestJunit.java

	@Test
	public void testAnimal(){
		Animal t = new Animal();
		t.setName("animal");
		session.saveOrUpdate(t);
	}
	
	@Test
	public void testCat(){
		Cat t = new Cat();
		t.setName("cat");
		t.setCatName("cat");
		session.saveOrUpdate(t);
	}
	
	@Test
	public void testDog(){
		Dog t = new Dog();
		t.setName("dog");
		t.setDogName("dog");
		session.saveOrUpdate(t);
	}

对应生成的数据表是这样的
table---Animal

id	name
1	animal
2	cat
3	dog

table---cat

catId	catName
2	cat

table---dog

dogId	dogName
3	dog

3、每个实体类对应一个数据表
以下的测试中，Anamal.java中的主键生成策略需要注解成@GeneratedValue(strategy=GenerationType.TABLE)，测试是在mysql数据库中进行的。
Animal.java

@Entity
@Inheritance(strategy=InheritanceType.TABLE_PER_CLASS)
public class Animal {
	private int id;
	private String name;
	
	@Id
	@GeneratedValue(strategy=GenerationType.TABLE)
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
}

Cat.java

@Entity
@Inheritance(strategy=InheritanceType.TABLE_PER_CLASS)
public class Cat extends Animal {

	private String catName;

	public String getCatName() {
		return catName;
	}
	public void setCatName(String catName) {
		this.catName = catName;
	}
}

Dog.java

@Entity
@Inheritance(strategy=InheritanceType.TABLE_PER_CLASS)
public class Dog extends Animal{
	private String dogName;

	public String getDogName() {
		return dogName;
	}
	public void setDogName(String dogName) {
		this.dogName = dogName;
	}
}

TestJunit.java

	@Test
	public void testAnimal(){
		Animal t = new Animal();
		t.setName("animal");
		session.saveOrUpdate(t);
	}
	
	@Test
	public void testCat(){
		Cat t = new Cat();
		t.setName("cat");
		t.setCatName("cat");
		session.saveOrUpdate(t);
	}
	
	@Test
	public void testDog(){
		Dog t = new Dog();
		t.setName("dog");
		t.setDogName("dog");
		session.saveOrUpdate(t);
	}

对应生成的数据表是这样的
table---animal

id	name
1	animal

table---cat

id	name	catName
2	cat	cat

table---dog

id	name	dogName
3	dog	dog

评论

8 楼 cjnetwork 2014-11-17  

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7 楼 cjnetwork 2014-11-16  

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6 楼 cjnetwork 2014-11-16  

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5 楼 cjnetwork 2014-11-16  

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4 楼 cjnetwork 2014-11-16  

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3 楼 cjnetwork 2014-11-16  

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2 楼 cndavy 2014-09-24  

      good news

1 楼 ddcz 2011-12-01  

好文章,以前一直不会