Java克隆 Java实现克隆的三种方式实例总结

public class CloneTest1
{
  public static void main(String[] args) throws Exception
  {
    Student1 student = new Student1();
    student.setAge(24);
    student.setName("niesong");
    Student1 student2 = (Student1)student.clone();
    //这个是调用下面的那个方法，然后把这个这个对象Clone到student
    System.out.println("Age:" + student2.getAge() + " " + "Name:" + student2.getName());
    System.out.println("---------------------");
    student2.setAge(23);
    //克隆后得到的是一个新的对象，所以重新写的是student2这个对象的值
    System.out.println(student.getAge());
    System.out.println(student2.getAge());
  }
}
//克隆的对象必须实现Cloneable这个接口，而且需要重写clone方法
class Student1 implements Cloneable
{
  private int age;
  //定义为private说明这个成员变量只能被被当前类中访问，如果外部需要获得，那么就只能通过getAge方法进行获取
  private 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
  {
    Object object = super.clone();
    return object;
  }
}

public class CloneTest2
{
  public static void main(String[] args) throws Exception
  {
    Teacher teacher = new Teacher();
    teacher.setAge(40);
    teacher.setName("teacher zhang");
    Student2 student2 = new Student2();
    student2.setAge(14);
    student2.setName("lisi");
    student2.setTeacher(teacher);
    Student2 student3 = (Student2)student2.clone();
    //这里是深复制，所以这时候Student2中的teacher就是teacher这个对象的一个复制，就和student3是student2的一个复制
    //所以下面teacher.setName只是对他原来的这个对象更改，但是复制的那个并没有更改
    System.out.println(student3.getAge());
    System.out.println(student3.getName());
    System.out.println(student3.getTeacher().getAge());
    teacher.setName("teacher niesong");//不会又任何影响
    System.out.println(student3.getTeacher().getName());
  }
}
class Student2 implements Cloneable
{
  private int age;
  private String name;
  private 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
  {
    //这一步返回的这个student2还只是一个浅克隆，
    Student2 student2 = (Student2)super.clone();
    //然后克隆的过程中获得这个克隆的student2，然后调用这个getTeacher这个方方法得到这个Teacher对象。然后实现克隆。在设置到这个student2中的Teacher。
    //这样实现了双层克隆使得那个teacher对象也得到了复制。
    student2.setTeacher((Teacher)student2.getTeacher().clone());
    //双层克隆使得那个teacher对象也得到了复制
    return student2;
  }
}
class Teacher implements Cloneable
{
  private int age;
  private 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();
  }
}

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
public class CloneTest3
{
  public static void main(String[] args) throws Exception
  {
    Teacher3 teacher3 = new Teacher3();
    teacher3.setAge(23);
    teacher3.setName("niesong");
    Student3 student3 = new Student3();
    student3.setAge(50);
    student3.setName("wutao");
    student3.setTeacher3(teacher3);
    Student3 ss = (Student3)student3.deepCopt();
    System.out.println(ss.getAge());
    System.out.println(ss.getName());
    System.out.println("---------------------");
    System.out.println(ss.getTeacher3().getAge());
    System.out.println(ss.getTeacher3().getName());
    System.out.println("-----------------------");
    ss.getTeacher3().setAge(7777);
    ss.getTeacher3().setName("hhhhh");
    System.out.println(teacher3.getAge());
    System.out.println(teacher3.getName());
    //虽然上面的已经改了，但是改的是那个复制对象后的那个里面的，然后那个原来的那个里面的并没有改，下面验证：：：
    System.out.println("-----------------");
    System.out.println(ss.getTeacher3().getAge());
    System.out.println(ss.getTeacher3().getName());
  }
}
class Teacher3 implements Serializable
{
// 上面的那个警告可以直接消除，除了使用在设置中不显示这个警告，还可以使用下面的这两条语句中的任何一条语句
//  这个serialVersionUID为了让该类别Serializable向后兼容
//  private static final long serialVersionUID = 1L;
//  private static final long serialVersionUID = 8940196742313994740L;
  private int age;
  private 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 Student3 implements Serializable
{
  private static final long serialVersionUID = 1L;
  private int age;
  private String name;
  private Teacher3 teacher3;
  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 Teacher3 getTeacher3()
  {
    return teacher3;
  }
  public void setTeacher3(Teacher3 teacher3)
  {
    this.teacher3 = teacher3;
  }
  //使得序列化student3的时候也会将teacher序列化
  public Object deepCopt()throws Exception
  {
    ByteArrayOutputStream bos = new ByteArrayOutputStream();
    ObjectOutputStream oos = new ObjectOutputStream(bos);
    oos.writeObject(this);
    //将当前这个对象写到一个输出流当中，，因为这个对象的类实现了Serializable这个接口，所以在这个类中
    //有一个引用，这个引用如果实现了序列化，那么这个也会写到这个输出流当中
    ByteArrayInputStream bis = new ByteArrayInputStream(bos.toByteArray());
    ObjectInputStream ois = new ObjectInputStream(bis);
    return ois.readObject();
    //这个就是将流中的东西读出类，读到一个对象流当中，这样就可以返回这两个对象的东西，实现深克隆
  }
}