其實所有的java對象都可以具備克隆能力，只是因為在基礎類Object中被設定成了一個保留方法（protected),要想真正擁有克隆的能力，
就需要實現Cloneable接口，重寫clone方法。通過克隆方法得到的對象是一個本地的副本。
1、實現Cloneable接口
具體看代碼：
class User implements Cloneable{
int age;
public User(int age){
//用this關鍵字不至于類成員變量與形參混淆
this.age=age;
}
//這里可加@Override也可不加，加了會自動提示是否正確
@Override
public?Object clone{
Object o=null;
try{
o=super.clone();
}catch(CloneNotSupportedException e){
e.printStackTrace();
}
}
public String toString(){
return Integer.toString(this.age);
}
}
2、自己手動寫一個CloneUtil 工具類，不是實現Cloneable這種方式，但是能達到效果。
package cn.com.util;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
/**
?* 對象clone 工具類
?* @author
?*
?*/
public class CloneUtil {
?? ?public static Object clone(Serializable obj) {
?? ??? ?Object clone = cloneObject(obj);
?? ??? ?if (clone == null) {
?? ??? ??? ?clone = cloneObject(obj);
?? ??? ?}
?? ??? ?return clone;
?? ?}
?? ?public static Object cloneObject(Serializable obj) {
?? ??? ?Object anotherObj = null;
?? ??? ?ByteArrayOutputStream baos = new ByteArrayOutputStream();
?? ??? ?ObjectOutputStream oos = null;
?? ??? ?ObjectInputStream ois = null;
?? ??? ?try {
?? ??? ??? ?oos = new ObjectOutputStream(baos);
?? ??? ??? ?oos.writeObject(obj);
?? ??? ??? ?byte[] bytes = baos.toByteArray();
?? ??? ??? ?ByteArrayInputStream bais = new ByteArrayInputStream(bytes);
?? ??? ??? ?ois = new ObjectInputStream(bais);
?? ??? ??? ?anotherObj = ois.readObject();
?? ??? ?} catch (IOException ex) {
?? ??? ??? ?throw new RuntimeException(ex.getMessage(), ex);
?? ??? ?} catch (ClassNotFoundException ex) {
?? ??? ??? ?throw new RuntimeException(ex.getMessage(), ex);
?? ??? ?} catch (StackOverflowError error) {
?? ??? ??? ?System.out.println("stack length " + error.getStackTrace().length);
?? ??? ??? ?error.printStackTrace();
?? ??? ??? ?return null;
?? ??? ?} finally {
?? ??? ??? ?if (oos != null)
?? ??? ??? ??? ?try {
?? ??? ??? ??? ??? ?oos.close();
?? ??? ??? ??? ?} catch (IOException localIOException3) {
?? ??? ??? ??? ?}
?? ??? ??? ?if (ois != null)
?? ??? ??? ??? ?try {
?? ??? ??? ??? ??? ?ois.close();
?? ??? ??? ??? ?} catch (IOException localIOException4) {
?? ??? ??? ??? ?}
?? ??? ?}
?? ??? ?return anotherObj;
?? ?}
?? ?public static int getObjectSize(Serializable obj) {
?? ??? ?ByteArrayOutputStream bs = new ByteArrayOutputStream();
?? ??? ?try {
?? ??? ??? ?ObjectOutputStream os = new ObjectOutputStream(bs);
?? ??? ??? ?os.writeObject(obj);
?? ??? ??? ?os.flush();
?? ??? ?} catch (Exception e) {
?? ??? ??? ?throw new RuntimeException(e.getMessage(), e);
?? ??? ?}
?? ??? ?return bs.size();
?? ?}
}
?
)
