java中 对象的克隆(clone)

java中 克隆一个对象需要三步：
1：克隆的对象实现 Cloneable 标识接口
2：覆盖 Object 的 clone() 方法，在 clone() 方法中调用super.clone()，并把 protected 改为 public。
3：调用 clone() 克隆对象 ，如：代码第7行


克隆代码示例：

public class Test {

	public static void main(String[] args) {
		Professor p=new Professor("lisi",66);
		Student s1=new Student("zhaoliu",22,p);
		
		Student s2=(Student)s1.clone();
//深复制  -- 把s1的引用拷贝一份  赋值给s2 ，所以 改变s2的值  s1不改变 ，即输出（name=lisi,age=66）
		//Student s2=(Student)s1;
//浅复制  --只把s1的引用 赋值给s2 , 所以 改变s2的值  s1也改变 ，即输出（name=wangwu,age=40）
		s2.getP().setName("wangwu");
		s2.getP().setAge(40);
		System.out.println("name="+s1.getP().getName()+","+"age="+s1.getP().getAge());
	}
}

class Professor implements Cloneable {
	private String name;
	private int age;

	Professor(String name, int age) {
		this.name = name;
		this.age = age;
	}

	public Object clone() {
		Object o = null;
		try {
			o = super.clone();
		} catch (CloneNotSupportedException e) {
			System.out.println(e.toString());
		}
		return o;
	}

	public String getName() {
		return name;
	}

	public int getAge() {
		return age;
	}

	public void setName(String name) {
		this.name = name;
	}

	public void setAge(int age) {
		this.age = age;
	}
	
}

class Student implements Cloneable {
	private String name;
	private int age;
	private Professor p;

	Student(String name, int age, Professor p) {
		this.name = name;
		this.age = age;
		this.p = p;
	}

	public Object clone() {
		// Object o=null;
		Student o = null;
		try {
			o = (Student) super.clone();
		} catch (CloneNotSupportedException e) {
			System.out.println(e.toString());
		}
		o.p = (Professor) p.clone();
		return o;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}

	public Professor getP() {
		return p;
	}

	public void setP(Professor p) {
		this.p = p;
	}
	
}