1. ??? ???? ??? ??????

??? ???? ?? ??? ?? ?? ???? ????? ?? ??? ???? ???. Java ??? ??? ??? ????? ?? ????.

2. ?? ??? ???? ??? ??????

? ?? ??? ????:

(?? ????: java ?? ????)

(1) Cloneable ?????? ???? Object ????? clone() ???? ?? ?????.

(2) ??? ?? ?????? ?????. , through ??? ??? ? ????? ?? ??? ????, ?? ??? ?? ??? ??? ? ????. ??? ??? ????.

 
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
 
public class MyUtil {
 
    private MyUtil() {
        throw new AssertionError();
    }
 
    @SuppressWarnings("unchecked")
    public static <T extends Serializable> T clone(T obj) throws Exception {
        ByteArrayOutputStream bout = new ByteArrayOutputStream();
        ObjectOutputStream oos = new ObjectOutputStream(bout);
        oos.writeObject(obj);
 
        ByteArrayInputStream bin = new ByteArrayInputStream(bout.toByteArray());
        ObjectInputStream ois = new ObjectInputStream(bin);
        return (T) ois.readObject();
 
        // 說明：調用ByteArrayInputStream或ByteArrayOutputStream對象的close方法沒有任何意義
        // 這兩個基于內存的流只要垃圾回收器清理對象就能夠釋放資源，這一點不同于對外部資源（如文件流）的釋放
    }
}

??? ??? ?????.

 
import java.io.Serializable;
 
/**
 * 人類
 * @author nnngu
 *
 */
class Person implements Serializable {
    private static final long serialVersionUID = -9102017020286042305L;
 
    private String name;    // 姓名
    private int age;        // 年齡
    private Car car;        // 座駕
 
    public Person(String name, int age, Car car) {
        this.name = name;
        this.age = age;
        this.car = car;
    }
 
    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 Car getCar() {
        return car;
    }
 
    public void setCar(Car car) {
        this.car = car;
    }
 
    @Override
    public String toString() {
        return "Person [name=" + name + ", age=" + age + ", car=" + car + "]";
    }
 
}

 
/**
 * 小汽車類
 * @author nnngu
 *
 */
class Car implements Serializable {
    private static final long serialVersionUID = -5713945027627603702L;
 
    private String brand;       // 品牌
    private int maxSpeed;       // 最高時速
 
    public Car(String brand, int maxSpeed) {
        this.brand = brand;
        this.maxSpeed = maxSpeed;
    }
 
    public String getBrand() {
        return brand;
    }
 
    public void setBrand(String brand) {
        this.brand = brand;
    }
 
    public int getMaxSpeed() {
        return maxSpeed;
    }
 
    public void setMaxSpeed(int maxSpeed) {
        this.maxSpeed = maxSpeed;
    }
 
    @Override
    public String toString() {
        return "Car [brand=" + brand + ", maxSpeed=" + maxSpeed + "]";
    }
 
}

class CloneTest {
 
    public static void main(String[] args) {
        try {
            Person p1 = new Person("郭靖", 33, new Car("Benz", 300));
            Person p2 = MyUtil.clone(p1);   // 深度克隆
            p2.getCar().setBrand("BYD");
            // 修改克隆的Person對象p2關聯(lián)的汽車對象的品牌屬性
            // 原來的Person對象p1關聯(lián)的汽車不會受到任何影響
            // 因為在克隆Person對象時其關聯(lián)的汽車對象也被克隆了
            System.out.println(p1);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

??: ??? ? ????? ???? ? ??? ?? ?? ?? ????. cloning. ? ??? ?? ?? ??? ?? ??? ??? ???? ????? ??? ? ??? ????. ? ??? ????? ?? ???? ???? ??? ????? ????. ? ???? ??? Object ???? ???? ??? ????. clone ???? ??? ?????. ??? ???? ??? ?? ??? ??? ??? ??? ????? ?? ?? ? ????.

(?? ??? ????: java ??? ????)

3. ?? ??? ?? ??? ???? ??????

?? ??? ??? ?? ??? ???? ?????. ? ??? ????? ??? ??? ????? ?? ???? ?? ?? ?? ?? ?????(?: ??()).

? ??? ??? ?? ?? ???? ????. ? ??? ? ? ???? ???? ?? ?? ???? ????(?: JSON.parse() ? JSON.stringify( ), ??? ? ??? ??? ??? ? ????. Type)

? ?? ?? ?? ??: java ?? ??

? ??? 2020? ??? Java ?? ?? - ?? ??? ?? ?????. ??? ??? PHP ??? ????? ?? ?? ??? ?????!