BaseEntity实体的继承：@MappedSuperclass

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在创建实体时，经常有重复的id和时间的属性要创建，所以想弄一个父类，然后所有实体继承，但是碰到了问题，就用到了@MappedSuperclass，它的的用法
用在实体的继承过程中的父类上；
如：
IdEntity.java

package com.zpf.test.Entity;

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

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

/**
 * 基础实体类
 *
 * @author zpf
 *
 */
@MappedSuperclass
public class IdEntity implements Serializable {

    /**
     *
     */
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long id;

    @Column(updatable = false)
    private Date createDate;
    private Date modifyDate;

    public long getId() {
        return id;
    }

    public void setId(long id) {
        this.id = id;
    }

    public Date getCreateDate() {
        return createDate;
    }

    public void setCreateDate(Date createDate) {
        this.createDate = createDate;
    }

    public Date getModifyDate() {
        return modifyDate;
    }

    public void setModifyDate(Date modifyDate) {
        this.modifyDate = modifyDate;
    }

}

package com.zpf.test.Entity;
import java.io.Serializable;

import java.util.Date;
import javax.persistence.Column;

import javax.persistence.GeneratedValue;

import javax.persistence.GenerationType;

import javax.persistence.Id;

import javax.persistence.MappedSuperclass;
/**

基础实体类

@author zpf


*/

@MappedSuperclass

public class IdEntity implements Serializable {
/**
 * 
 */
private static final long serialVersionUID = 1L;

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private long id;

@Column(updatable = false)
private Date createDate;
private Date modifyDate;

public long getId() {
	return id;
}

public void setId(long id) {
	this.id = id;
}

public Date getCreateDate() {
	return createDate;
}

public void setCreateDate(Date createDate) {
	this.createDate = createDate;
}

public Date getModifyDate() {
	return modifyDate;
}

public void setModifyDate(Date modifyDate) {
	this.modifyDate = modifyDate;
}

}

package com.zpf.test.Entity;

import java.io.Serializable;

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

/**
 * 用户实体
 * @author zpf
 *
 */
@Entity
@Table(name="tb_user")
public class User extends IdEntity implements Serializable{

    private static final long serialVersionUID = 1L;

    private String name;

    private String sex;

    private int age;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }


}

package com.zpf.test.Entity;
import java.io.Serializable;
import javax.persistence.Entity;

import javax.persistence.Table;
/**

用户实体
@author zpf


*/

@Entity

@Table(name="tb_user")

public class User extends IdEntity implements Serializable{
private static final long serialVersionUID = 1L;

private String name;

private String sex;

private int age;

public String getName() {
	return name;
}

public void setName(String name) {
	this.name = name;
}

public String getSex() {
	return sex;
}

public void setSex(String sex) {
	this.sex = sex;
}

public int getAge() {
	return age;
}

public void setAge(int age) {
	this.age = age;
}

}

这样就会生成tb_user表而且包含父类属性，否则只会生成一张identity表，字段有：id，crearedate,modifydate,name，sex，age 原文地址：https://www.iteye.com/blog/peng13123-2062980