@MappedSuperclass的用法

一、定義實體類的父類

package com.rock.cft.hibernate;

import java.util.Date;

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

//@MappedSuperclass 用在父類上面。當這個類確定是父類時，加此標註。若是改爲@Entity，則繼承後，多個類繼承，只會生成一個表，而不是多個繼承，生成多個表
@MappedSuperclass
public abstract class BaseEntity {
  private Integer id;// 數據庫主鍵
 private Date creationTime;//建立時間
 private Date modificationTime;//修改時間
 
 @Id
 @GeneratedValue(strategy = GenerationType.AUTO)
 public Integer getId() {
  return id;
 }
 public void setId(Integer id) {
  this.id = id;
 }
 public Date getCreationTime() {
  return creationTime;
 }
 public void setCreationTime(Date creationTime) {
  this.creationTime = creationTime;
 }
 public Date getModificationTime() {
  return modificationTime;
 }
 public void setModificationTime(Date modificationTime) {
  this.modificationTime = modificationTime;
 }
 
}

二、實體類Test_No1.java

package com.rock.cft.test.model;

import java.io.Serializable;
import java.util.Date;

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

import com.rock.cft.hibernate.BaseEntity;

@Entity
@Table(name="test_no2")
public class Test_No1 extends BaseEntity implements Serializable {
 

 private String name;
 private int age;

 public String getName() {
  return name;
 }
 public void setName(String name) {
  this.name = name;
 }
 public int getAge() {
  return age;
 }
 public void setAge(int age) {
  this.age = age;
 }
  

}

三、實體類Test_NO2.java

package com.rock.cft.test.model;

import java.io.Serializable;
import java.util.Date;

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

import com.rock.cft.hibernate.BaseEntity;

@Entity
@Table(name="test_no2")
public class Test_NO2 extends BaseEntity implements Serializable {
 
 
 private Date testBri;
 
 private String testAdr;
 
 public Date getTestBri() {
  return testBri;
 }
 public void setTestBri(Date testBri) {
  this.testBri = testBri;
 }
 public String getTestAdr() {
  return testAdr;
 }
 public void setTestAdr(String testAdr) {
  this.testAdr = testAdr;
 }
}

這樣在生成表的時候只生成了：test_no一、test_no2兩張表，並且兩張表中都含有id、creationTime、modificationTime三個屬性

可是若是把@MappedSuperclass換成@Entity那麼就會另外在生成一張baseEntity的表