问IP层防止被攻击？

public class Deletable implements Cloneable{

    private String str;

    public Deletable(){

    }

    public void setStr(String str){

        this.str = str;

    }

    public void display(){

        System.out.println("The String is "+str);

    }

    protected Object clone() throws CloneNotSupportedException {

        return super.clone();

    }

}

Deletable del = new Deletable();

Deletable delTemp = (Deletable ) del.clone(); // this line will return you an independent

                                 // object, the changes made to this object will

                                 // not be reflected to other object

class DummyBean {

  private String dummy;

  public DummyBean(DummyBean another) {

    this.dummy = another.dummy; // you can access  

  }

}