对象的深度拷贝

 public static Object deepClone(Object obj) {  
            try {// 将对象写到流里  
                ByteArrayOutputStream bo = new ByteArrayOutputStream();  
                ObjectOutputStream oo = new ObjectOutputStream(bo);  

                oo.writeObject(obj);

               // 从流里读出来  

                ByteArrayInputStream bi = new ByteArrayInputStream(bo.toByteArray());  
                ObjectInputStream oi = new ObjectInputStream(bi);  
                return (oi.readObject());  
            } catch (Exception e) {  
                return null;  
            }  
        }