Java中实现深拷贝的两种方式--——clone() & Serialized

• clone() 方法麻烦一些，需要将所有涉及到的类实现声明式接口 Cloneable，并覆盖Object类中的clone()方法，并设置作用域为public（这是为了其他类可以使用到该clone方法）。

• 序列化的方法简单，需要将所有涉及到的类实现接口Serializable

package b1ch06.clone;

import java.io.Serializable;

class Car implements Cloneable, Serializable {
    private String band;

    public Car(String band) {
        this.band = band;
    }

    public String getBand() {
        return band;
    }

    public void setBand(String band) {
        this.band = band;
    }

    @Override
    public Object clone() throws CloneNotSupportedException {
        return super.clone();
    }
}

package b1ch06.clone;

import java.io.Serializable;

class Employee implements Cloneable, Serializable {
    private String name;
    private Car car;

    public Employee(String name, Car car) {
        this.name = name;
        this.car = car;
    }

    public String getName() {
        return name;
    }

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

    public Car getcar() {
        return car;
    }

    public void setcar(Car car) {
        this.car = car;
    }

    protected void test() {
        System.out.println("test func");
    }

    @Override
    public Object clone() throws CloneNotSupportedException {

        Employee employee_cloned = (Employee) super.clone();
        Car car_cloned = (Car) this.car.clone();
        employee_cloned.setcar(car_cloned);
        return employee_cloned;
    }
}

package b1ch06.clone;


import java.io.*;


public class SerializedClone {
    @SuppressWarnings("unchecked")
    public static <T extends Serializable> T clone(T obj) {
        T cloneObj = null;
        try {
            //写入字节流
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            ObjectOutputStream obs = new ObjectOutputStream(out);
            obs.writeObject(obj);
            obs.close();

            //分配内存，写入原始对象，生成新对象
            ByteArrayInputStream ios = new ByteArrayInputStream(out.toByteArray());
            ObjectInputStream ois = new ObjectInputStream(ios);
            //返回生成的新对象
            cloneObj = (T) ois.readObject();
            ois.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return cloneObj;
    }


}

package b1ch06.clone;

public class MyClone {


    public static void main(String[] args) {
        Car car = new Car("BMW");
        Employee employee = new Employee("ANDY", car);
        // 方法一：覆盖所有涉及到的类的clone()方法
        try {

            Employee employee_cp = (Employee) employee.clone();

            System.out.println("=========================");
            System.out.println("original对象地址?:");
            System.out.println(employee.toString());
            System.out.println("copy对象地址?:");
            System.out.println(employee_cp.toString());
            System.out.println("前后两个对象指向同一地址?:");
            System.out.println(employee_cp == employee);
            System.out.println("=========================");

            System.out.println("original对象中car对象地址?:");
            System.out.println(employee.getcar().toString());
            System.out.println("copy对象中car对象地址?:");
            System.out.println(employee_cp.getcar().toString());
            System.out.println("前后两个car对象指向同一地址?:");
            System.out.println(employee_cp == employee);

        } catch (CloneNotSupportedException e) {
            e.printStackTrace();
        }

        // 方法二：序列化实现深拷贝
        Employee cloned_employee = SerializedClone.clone(employee);
        System.out.println("=========================");
        System.out.println("original对象地址?:");
        System.out.println(employee.toString());
        System.out.println("copy对象地址?:");
        System.out.println(cloned_employee.toString());
        System.out.println("前后两个对象指向同一地址?:");
        System.out.println(cloned_employee == employee);

        System.out.println("=========================");

        System.out.println("original对象中car对象地址?:");
        System.out.println(employee.getcar().toString());
        System.out.println("copy对象中car对象地址?:");
        System.out.println(cloned_employee.getcar().toString());
        System.out.println("前后两个car对象指向同一地址?:");
        System.out.println(cloned_employee == employee);

    }
}