其实所有的java对象都可以具备克隆能力，只是因为在基础类Object中被设定成了一个保留方法（protected),要想真正拥有克隆的能力，
就需要实现Cloneable接口，重写clone方法。通过克隆方法得到的对象是一个本地的副本。
1、实现Cloneable接口
具体看代码：
class User implements Cloneable{
int age;
public User(int age){
//用this关键字不至于类成员变量与形参混淆
this.age=age;
}
//这里可加@Override也可不加，加了会自动提示是否正确
@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、自己手动写一个CloneUtil 工具类，不是实现Cloneable这种方式，但是能达到效果。
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;
/**
* 对象clone 工具类
* @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();
}
}