java 原型模式之深复制与浅复制
转载自：http://blog.csdn.net/liu_yujie2011com/article/details/40510567
Java支持我们对一个对象进行克隆，通常用在装饰模式和原型模式中。那么什么是深克隆，什么是浅克隆呢。
【浅克隆】，通常只是对克隆的实例进行复制，但里面的其他子对象，都是共用的。
【深克隆】，克隆的时候会复制它的子对象的引用，里面所有的变量和子对象都是又额外拷贝了一份。
下面的两个例子可以很好的说明他们的区别：
Husband类有一个对wife的引用，当进行浅克隆的时，wife变量都会指向同一个Wife；而进行深克隆时，会指向不同的Wife。下面进行一下验证：
【浅克隆】
public Object clone() {
Husband husband = null;
try{
husband = (Husband)super.clone();
}catch(CloneNotSupportedException e){
e.printStackTrace();
}finally{
return husband;
}
}
【深克隆】
public Object deepClone() throws IOException,ClassNotFoundException {
//将对象写到流里
ByteArrayOutputStream bos = new ByteArrayOutputStream();
ObjectOutputStream oos = new ObjectOutputStream(bos);
oos.writeObject(this);
//从流里读回来
ByteArrayInputStream bis = new ByteArrayInputStream(bos.toByteArray());
ObjectInputStream ois = new ObjectInputStream(bis);
return ois.readObject();
}
【全部代码】
package com.xingoo.clone;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.Date;
class Wife implements Serializable{
private String name;
private Date birthday;
public Wife(){
name = "芙蓉姐姐";
birthday = new Date();
}
public Date getBirthday(){
return birthday;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
class Husband implements Cloneable,Serializable{
private Wife wife;
private Date birthday;
public Husband(){
wife = new Wife();
birthday = new Date();
}
public Wife getWife(){
return wife;
}
public Date getBirthday(){
return birthday;
}
/**
* 浅克隆一个对象
*/
public Object clone() {
Husband husband = null;
try{
husband = (Husband)super.clone();
}catch(CloneNotSupportedException e){
e.printStackTrace();
}finally{
return husband;
}
}
/**
* 利用串行化深克隆一个对象，把对象以及它的引用读到流里，在写入其他的对象
* @return
* @throws IOException
* @throws ClassNotFoundException
*/
public Object deepClone() throws IOException,ClassNotFoundException {
//将对象写到流里
ByteArrayOutputStream bos = new ByteArrayOutputStream();
ObjectOutputStream oos = new ObjectOutputStream(bos);
oos.writeObject(this);
//从流里读回来
ByteArrayInputStream bis = new ByteArrayInputStream(bos.toByteArray());
ObjectInputStream ois = new ObjectInputStream(bis);
return ois.readObject();
}
}
public class Test {
public static void main(String[] args){
try{
Husband husband = new Husband();
System.out.println("husband birthday "+husband.getBirthday().getTime());
System.out.println("wife birthday "+husband.getWife().getBirthday().getTime());
System.out.println();
Husband husband1 = (Husband)husband.clone();
System.out.println("husband1 birthday "+husband1.getBirthday().getTime());
System.out.println("wife birthday "+husband1.getWife().getBirthday().getTime());
System.out.println();
System.out.println("是否是同一个husband "+(husband == husband1));
System.out.println("是否是同一个wife "+ (husband.getWife() == husband1.getWife()));
System.out.println();
Husband husband2 = (Husband)husband.deepClone();
System.out.println("husband2 birthday "+husband2.getBirthday().getTime());
System.out.println("wife birthday "+husband2.getWife().getBirthday().getTime());
System.out.println();
System.out.println("是否是同一个husband "+(husband == husband2));
System.out.println("是否是同一个wife "+ (husband.getWife() == husband2.getWife()));
}catch(Exception e){
e.printStackTrace();
}
}
}
【运行结果】
husband birthday 1414247244668
wife birthday 1414247244668
husband1 birthday 1414247244668
wife birthday 1414247244668
是否是同一个husband false
是否是同一个wife true
husband2 birthday 1414247244668
wife birthday 1414247244668
是否是同一个husband false
是否是同一个wife false