java 克隆clone

1.java里的clone分为： 
  A:浅复制（浅克隆）: 浅复制仅仅复制所考虑的对象，而不复制它所引用的对象。 
  B:深复制（深克隆）：深复制把要复制的对象所引用的对象都复制了一遍。 
Java中对象的克隆,为了获取对象的一份拷贝，我们可以利用Object类的clone()方法。必须要遵循下面三点 
  1.在派生类中覆盖基类的clone()方法，并声明为public【Object类中的clone()方法为protected的】。 
  2.在派生类的clone()方法中，调用super.clone()。 
  3.在派生类中实现Cloneable接口。 

Object类里的clone方法是浅复制（浅克隆） 

1 浅复制 （浅克隆）的例子如下：

package com.test;    //浅复制（浅克隆）: 浅复制仅仅复制所考虑的对象，而不复制它所引用的对象。  //深复制（深克隆）：深复制把要复制的对象所引用的对象都复制了一遍。  //  //Java中对象的克隆,为了获取对象的一份拷贝，我们可以利用Object类的clone()方法。必须要遵循下面三点  //1.在派生类中覆盖基类的clone()方法，并声明为public【Object类中的clone()方法为protected的】。  //2.在派生类的clone()方法中，调用super.clone()。  //3.在派生类中实现Cloneable接口。    //Object类里的clone方法是浅复制（浅克隆）public class CloneTest {        public static void main(String[] args) throws Exception{          //teacher对象将被clone出来的Student对象共享.          Teacher teacher = new Teacher();          teacher.setAge(40);          teacher.setName("Teacher zhang");                    Student student1 = new Student();          student1.setAge(20);          student1.setName("zhangsan");          student1.setTeacher(teacher);                    //复制出来一个对象student2          Student student2 = (Student)student1.clone();          System.out.println(student2.getAge());          System.out.println(student2.getName());                              System.out.println("~~~~~~~~~~~~~~~~~~~~~~");          System.out.println(student1.getTeacher().getAge());          System.out.println(student1.getTeacher().getName());                              //修改student2的引用对象          student2.getTeacher().setAge(50);          student2.getTeacher().setName("Teacher Li");                    System.out.println("~~~~~~~~~~~~~~~~~~~~~~");          System.out.println(student1.getTeacher().getAge());          System.out.println(student1.getTeacher().getName());      }  }  

class Teacher {      public int age;      public String name;            public int getAge() {          return age;      }      public void setAge(int age) {          this.age = age;      }      public String getName() {          return name;      }      public void setName(String name) {          this.name = name;      }              }  

class Student implements Cloneable{            public int age ;      public String name;      public Teacher teacher;      public int getAge() {          return age;      }      public void setAge(int age) {          this.age = age;      }      public String getName() {          return name;      }      public void setName(String name) {          this.name = name;      }      public Teacher getTeacher() {          return teacher;      }      public void setTeacher(Teacher teacher) {          this.teacher = teacher;      }      @Override      public Object clone() throws CloneNotSupportedException {          return super.clone();      }             }  

输出结果为：  
20  
zhangsan  
~~~~~~~~~~~~~~~~~~~~~~  
40  
Teacher zhang  
~~~~~~~~~~~~~~~~~~~~~~  
50  
Teacher Li  


2 .深复制（深Clone）例子： 

package com.test1;    //深clone  public class DeepCloneTest {        public static void main(String[] args) throws Exception{          //teacher对象将不被clone出来的Student对象共享.          Teacher teacher = new Teacher();          teacher.setAge(40);          teacher.setName("Teacher zhang");                    Student student1 = new Student();          student1.setAge(20);          student1.setName("zhangsan");          student1.setTeacher(teacher);                    //复制出来一个对象student2          Student student2 = (Student)student1.clone();          System.out.println(student2.getAge());          System.out.println(student2.getName());                              System.out.println("~~~~~~~~~~~~~~~~~~~~~~");          System.out.println(student1.getTeacher().getAge());          System.out.println(student1.getTeacher().getName());                              //修改student2的引用对象          student2.getTeacher().setAge(50);          student2.getTeacher().setName("Teacher Li");                    System.out.println("~~~~~~~~~~~~~~~~~~~~~~");          System.out.println(student1.getTeacher().getAge());          System.out.println(student1.getTeacher().getName());      }  }  

class Teacher implements Cloneable{      public int age;      public String name;            public int getAge() {          return age;      }      public void setAge(int age) {          this.age = age;      }      public String getName() {          return name;      }      public void setName(String name) {          this.name = name;      }      @Override      public Object clone() throws CloneNotSupportedException {          return super.clone();      }        }    class Student implements Cloneable{            public int age ;      public String name;      public Teacher teacher;      public int getAge() {          return age;      }      public void setAge(int age) {          this.age = age;      }      public String getName() {          return name;      }      public void setName(String name) {          this.name = name;      }      public Teacher getTeacher() {          return teacher;      }      public void setTeacher(Teacher teacher) {          this.teacher = teacher;      }      @Override      public Object clone() throws CloneNotSupportedException {          Student student = (Student)super.clone();          //将引用的对象teacher也clone下          student.setTeacher((Teacher)(student.getTeacher().clone()));          return student;      }              }  

输出结果为：  
20  
zhangsan  
~~~~~~~~~~~~~~~~~~~~~~  
40  
Teacher zhang  
~~~~~~~~~~~~~~~~~~~~~~  
40  
Teacher zhang  


3.利用序列化来做深复制,把对象写到流里的过程是序列化（Serilization）过程，而把对象从流中读出来的过程则叫做反序列化（Deserialization）过程。应当指出的是，写在流里的是对象的一个拷贝，而原对象仍然存在于JVM里面。，利用这个特性，可以做深拷贝 

package com.test3;  
  
import java.io.ByteArrayInputStream;  
import java.io.ByteArrayOutputStream;  
import java.io.ObjectInputStream;  
import java.io.ObjectOutputStream;