Java的浅克隆和深克隆

浅克隆：对于对象的基本数据类型的变量，将值复制一份传递给新对象，是两份数据，对于引用类型变量，会将引用值也就是对象的地址复制一份传递给新对象，是同一份数据。

深克隆：对于基本数据类型的变量，将值复制一份传递给新对象，是两份数据，引用类型会将引用的对象复制一份，然后将新的对象地址传递给新对象。

浅拷贝：

直接上代码：根据地址可知引用类型并未复制，仍然是同一个对象。

public class User implements Cloneable{
	private String name;
	private int age;
	private Student student;
	
	public User(String name, int age, Student student) {
		this.name=name;
		this.age=age;
		this.student = student;
	}
	public String getName() {
		return name;
	}
	public Student getStudent() {
		return student;
	}
	public void setStudent(Student student) {
		this.student = student;
	}
	public void setName(String name) {
		this.name = name;
	}
	public int getAge() {
		return age;
	}
	public void setAge(int age) {
		this.age = age;
	}

	@Override
	protected Object clone() throws CloneNotSupportedException {
		return super.clone();
	}
	public static void main(String[] args) throws Exception{
		Student student = new Student();
		User user1 = new User("xiaoming", 12, student);
		User user2 = (User)user1.clone();
		System.out.println(student);
		System.out.println(user2.getStudent());
		System.out.println(user1);
		System.out.println(user2);
	}
}
class Student {
}

结果：
Student@6d06d69c
Student@6d06d69c
User@7852e922
User@4e25154f

 深拷贝：

1.重写clone方法，手动将引用类型复制。结果显示 student引用的是两个对象。

public class User implements Cloneable{
	private String name;
	private int age;
	private Student student;
	
	public User(String name, int age, Student student) {
		this.name=name;
		this.age=age;
		this.student = student;
	}
	public String getName() {
		return name;
	}
	public Student getStudent() {
		return student;
	}
	public void setStudent(Student student) {
		this.student = student;
	}
	public void setName(String name) {
		this.name = name;
	}
	public int getAge() {
		return age;
	}
	public void setAge(int age) {
		this.age = age;
	}

	@Override
	protected Object clone() throws CloneNotSupportedException {
		User user = (User)super.clone();
		Student student = (Student) user.getStudent().clone();
		user.setStudent(student);
		return user;
	}
	public static void main(String[] args) throws Exception{
		Student student = new Student();
		User user1 = new User("xiaoming", 12, student);
		User user2 = (User)user1.clone();
		System.out.println(student);
		System.out.println(user2.getStudent());
		System.out.println(user1);
		System.out.println(user2);
	}
}
class Student implements Cloneable{
	@Override
	protected Object clone() throws CloneNotSupportedException {
		return super.clone();
	}
}
结果：
Student@6d06d69c
Student@7852e922
User@4e25154f
User@70dea4e

2.序列化实现深拷贝

public class User implements Serializable{
	private static final long serialVersionUID = 5661776984610831718L;
	private String name;
	private int age;
	private Student student;
	
	public User(String name, int age, Student student) {
		this.name=name;
		this.age=age;
		this.student = student;
	}
	public String getName() {
		return name;
	}
	public Student getStudent() {
		return student;
	}
	public void setStudent(Student student) {
		this.student = student;
	}
	public void setName(String name) {
		this.name = name;
	}
	public int getAge() {
		return age;
	}
	public void setAge(int age) {
		this.age = age;
	}

	public static void main(String[] args) throws Exception{
		Student student = new Student();
		User user1 = new User("xiaoming", 12, student);
		FileOutputStream outputStream = new FileOutputStream(new File("d://User.txt"));
		ObjectOutputStream objectOutputStream = new ObjectOutputStream(outputStream);
		objectOutputStream.writeObject(user1);
		
		FileInputStream inputStream = new FileInputStream(new File("d://User.txt"));
		ObjectInputStream objectInputStream = new ObjectInputStream(inputStream);
		User user2 = (User)objectInputStream.readObject();
		System.out.println(user1);
		System.out.println(user2);
		System.out.println(user1.student);
		System.out.println(user2.student);
		
	}
}
class Student implements Serializable{
	private static final long serialVersionUID = 3218462002829068131L;
}
结果：
User@42a57993
User@4554617c
Student@4aa298b7
Student@74a14482