概念

原型模式屬于創(chuàng)建型模式，它提供了一種創(chuàng)建對象的最佳方式。是用于創(chuàng)建重復(fù)的對象，同時又能保證性能。指定創(chuàng)建對象的種類，通過拷貝復(fù)制這些原型，創(chuàng)建新的對象。當(dāng)直接創(chuàng)建對象的代價比較大時，則采用這種模式。

UML

拷貝方式

淺拷貝

@Data
@AllArgsConstructor
public class Parent {
    private String name;
}

@Data
@AllArgsConstructor
public class Sleep1 implements Cloneable {
    private String name;
    private int age;
    private String color;
//Parent 無需實(shí)現(xiàn)Cloneable 進(jìn)行拷貝
    private Parent parent;
    @Override
    protected Sleep1 clone() {
        Sleep1 sleep=null;
        try {
            sleep = (Sleep1) super.clone();
        } catch (CloneNotSupportedException e) {
            System.out.println("clone失敗");
        }
        return sleep;
    }
}

• 淺拷貝無法將屬性中為對象的類型加以拷貝，而是保存一份鏈接指向?qū)?yīng)對象

深拷貝

• 深拷貝則與淺拷貝相反，能將所有對象已經(jīng)屬性對象都拷貝一份

通過實(shí)現(xiàn)cloneable接口拷貝

• 缺點(diǎn)是所有引用的對象都需要實(shí)現(xiàn)拷貝，無限套娃，對類改動較大

@Data
@AllArgsConstructor
public class Child implements Cloneable {
    private String name;

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

@Data
@AllArgsConstructor
public class Sleep2 implements Cloneable {
    private String name;
    private int age;
    private String color;
    private Child child;

    //深拷貝
    @Override
    protected Sleep2 clone() {
        Sleep2 sleep=null;
        try {
            sleep = (Sleep2) super.clone();
            sleep.child=child.clone();
        } catch (CloneNotSupportedException e) {
            System.out.println("clone失敗");
        }
        return sleep;
    }
}

通過序列化來拷貝

@Data
@AllArgsConstructor
public class Sleep3 implements Serializable {
    private String name;
    private int age;
    private String color;
    private Parent parent;

    public Sleep3 depepClone() {
        ByteArrayOutputStream bos = null;
        ObjectOutputStream oos = null;
        ByteArrayInputStream bis = null;
        ObjectInputStream ois = null;
        try{
            //序列化
            bos=new ByteArrayOutputStream();
            oos=new ObjectOutputStream(bos);
            //將當(dāng)前對象以流方式輸出
            oos.writeObject(this);
            //反序列化
            bis=new ByteArrayInputStream(bos.toByteArray());
            ois=new ObjectInputStream(bis);
            Sleep3 sleep3=(Sleep3) ois.readObject();
            return sleep3;
        }catch (Exception e){
            System.out.println("反列化失敗");
            return null;
        }finally {
            try {
                bos.close();
                oos.close();
                bis.close();
                ois.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}