Hibernate继承映射(annotation)

三种方式：

1.一张总表SINGLE_TABLE

2.每个类分别一张表TABLE_PER_CLASS

3.每个子类一张表JOINED

第一种：只有一张总表，表中有个字段区分每条记录属于哪个子类

Person.java

package com.test.hiberenate.model;

import javax.persistence.DiscriminatorColumn;
import javax.persistence.DiscriminatorType;
import javax.persistence.DiscriminatorValue;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Inheritance;
import javax.persistence.InheritanceType;

@Entity
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name = "discriminator", discriminatorType = DiscriminatorType.STRING)
@DiscriminatorValue("person")
public class Person {
	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;
	}

}

 

Student.java

package com.test.hiberenate.model;

import javax.persistence.DiscriminatorValue;
import javax.persistence.Entity;

@Entity
@DiscriminatorValue("student")
public class Student extends Person {
	private int score;

	public int getScore() {
		return score;
	}

	public void setScore(int score) {
		this.score = score;
	}

}

 

Teacher.java

package com.test.hiberenate.model;

import javax.persistence.DiscriminatorValue;
import javax.persistence.Entity;

@Entity
@DiscriminatorValue("teacher")
public class Teacher extends Person {
	private String title;

	public String getTitle() {
		return title;
	}

	public void setTitle(String title) {
		this.title = title;
	}

}

 

生成的表：PERSON

 
 

第二种：每个类分别一张表，各个子类的记录之间没有重复的主键

Person.java

package com.test.hiberenate.model;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Inheritance;
import javax.persistence.InheritanceType;
import javax.persistence.TableGenerator;

@Entity
@Inheritance(strategy = InheritanceType.TABLE_PER_CLASS)
@TableGenerator(
		name = "t_gen", 
		table = "t_gen_table", 
		pkColumnName = "t_pk", 
		valueColumnName = "t_value", 
		pkColumnValue = "person_pk", 
		initialValue = 1, 
		allocationSize = 1)
public class Person {
	private int id;
	private String name;

	@Id
	@GeneratedValue(generator = "t_gen", 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;
	}

}

 

Student.java

package com.test.hiberenate.model;

import javax.persistence.Entity;

@Entity
public class Student extends Person {
	private int score;

	public int getScore() {
		return score;
	}

	public void setScore(int score) {
		this.score = score;
	}

}

 

Teacher.java

package com.test.hiberenate.model;

import javax.persistence.Entity;

@Entity
public class Teacher extends Person {
	private String title;

	public String getTitle() {
		return title;
	}

	public void setTitle(String title) {
		this.title = title;
	}

}

 

生成的表：

PERSON

 

 

T_GEN_TABLE(生成主键的表)

 

 

STUDENT

 

 

TEACHER

 

 

第三种：每个子类一张表

Person.java

package com.test.hiberenate.model;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Inheritance;
import javax.persistence.InheritanceType;

@Entity
@Inheritance(strategy = InheritanceType.JOINED)
public class Person {
	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;
	}

}

 

Student.java和Teacher.java同上

生成的表：

PERSON

 

 

STUDENT

 

 

TEACHER