Java中shallow clone 与deep Clone的区别

Java中实现对象clone的方式是implements Cloneable interface,然后在实现类中重写Object clone()方法．在Java中默认的是"shallow copy", 所以如果类的attribute中含有对象，并且希望实现"deep copy",就要将所涉及的类都 implements Cloneable and Serializable interfaces,　然后使用对象序列化的方式将对象写入disk,　然后再从disk中读出，并返回．

Example:

import java.util.Date;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.ObjectOutputStream;
import java.io.ObjectInputStream;
import java.io.IOException;
import java.io.OptionalDataException;
import java.io.Serializable;

public class Monkey implements Cloneable, Serializable
{

private int height;
private int weight;

/**
* @directed
* @clientCardinality 1
* @supplierCardinality 1
*/
private GoldRingedStaff staff;
private Date birthDate;

public Monkey()
{
this.birthDate = new Date();
this.staff = new GoldRingedStaff();
}

public Object deepClone()
throws IOException, OptionalDataException, ClassNotFoundException
{
//write to stream
ByteArrayOutputStream bo = new ByteArrayOutputStream();
ObjectOutputStream oo = new ObjectOutputStream(bo);
oo.writeObject(this);

//read from stream
ByteArrayInputStream bi = new ByteArrayInputStream(bo.toByteArray());
ObjectInputStream oi = new ObjectInputStream(bi);

return (oi.readObject());
}

public Object clone()
{
Monkey temp = null;
try
{
temp = (Monkey) super.clone();
}
catch(CloneNotSupportedException e)
{
System.out.println("Clone failed");
}
finally
{
return temp;
}
}

public int getHeight()
{
return height;
}

public void setHeight(int height)
{
this.height = height;
}

public int getWeight()
{
return weight;
}

public void setWeight(int weight)
{
this.weight = weight;
}

public Date getBirthDate()
{
return birthDate;
}

public void setBirthDate(Date birthDate)
{
this.birthDate = birthDate;
}

public GoldRingedStaff getStaff()
{
return staff;
}

}