設計模式【三】原型模式

1. 代碼示例

import java.io.*;
import java.util.ArrayList;
import java.util.List;

/**
 * @authod: pp_lan on 2020/3/20.
 * 原型模式：淺複製、深複製
 */
public class ProtoType {

    /**
     * 深複製 實現序列化接口Serializable
     * @param t
     * @param <T>
     * @return
     * @throws IOException
     * @throws ClassNotFoundException
     */
    public static  <T> T deepCopy(T t) throws IOException, ClassNotFoundException {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        ObjectOutputStream oops = new ObjectOutputStream(baos);
        oops.writeObject(t);

        ObjectInputStream ois = new ObjectInputStream(new ByteArrayInputStream(baos.toByteArray()));
        return (T) ois.readObject();

    }

    /**
     * 淺複製 實現Cloneable接口
     * @param car
     * @return
     * @throws CloneNotSupportedException
     */
    public static Car clone (Car car) throws CloneNotSupportedException {
        return car.clone();
    }

    public static void main(String[] args) throws CloneNotSupportedException, IOException, ClassNotFoundException {
        Car car = new Car("奔馳");
        Car clone = clone(car);
        Car deepCopy = deepCopy(car);

        clone.setName("寶馬");
        clone.getList().add("真皮座椅");

        deepCopy.setName("雷克薩斯");
        deepCopy.getList().add("安全氣囊");

        System.out.println(car.getName());
        System.out.println(clone.getName());
        System.out.println(deepCopy.getName());

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

        System.out.println(car.getList());
        System.out.println(clone.getList());
        System.out.println(deepCopy.getList());

    }

}


class Car implements Cloneable, Serializable {

    private String name;

    private List<String> list;

    public Car(String name) {
        this.name = name;
        this.list = new ArrayList<>();
        list.add("輪胎");
        list.add("車身");
    }

    public String getName() {
        return name;
    }

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

    public List<String> getList() {
        return list;
    }

    public void setList(List<String> list) {
        this.list = list;
    }

    @Override
    protected Car clone() throws CloneNotSupportedException {
        return (Car) super.clone();
    }
}

2. 運行結果

奔馳
寶馬
雷克薩斯
=============
[輪胎, 車身, 真皮座椅]
[輪胎, 車身, 真皮座椅]
[輪胎, 車身, 安全氣囊]

3. 結論

淺複製後的值傳遞變量不會改變原對象值，但是地址指向的變量會改變原對象值；

深複製二者都不改變。