Prototype模式(设计模式)

适用场景:
    JAVA创建类实例基本上是适用new关键字。有时候需要使用 “在不指定类名的前提下生成实例”的需求。
    对象种类繁多,无法将他们整合到一个类中
    难以根据类生成实例
    解耦框架和生成的实例
一旦在类中使用到了别的类名,就意味着该类与其他类紧密的耦合在一起了
一旦在代码中出现要使用的类的名字,就不能和该类分离,也无法实现复用。也就意味着两者是耦合在一起的。

clone方法和java.lang.Clonable接口

被复制对象的类必须实现java.lang.Cloneable接口,否则调用clone()会产生CloneNotSupportedException异常。
clone()方法进行的是浅拷贝
Cloneable接口只是一个标识接口,clone是Object类中的native方法(https://www.cnblogs.com/KingIceMou/p/7239668.html)

Prototype模式.png

小案例

Product.java

package framework;
/**
 * @Author:DarknessShadow
 * @description:框架 - 产品类
 * @date 2020/5/12 13:36
 */
public interface Product extends Cloneable {
    public abstract void use(String s);
    public abstract Product creatClone();
}

Manager.java

package framework;
import java.util.HashMap;
import java.util.Map;
/**
 * @Author:DarknessShadow
 * @description:框架 - 管理类
 * @date 2020/5/12 13:53
 */
public class Manager {
    private Map showcase = new HashMap();
    public void register(String name, Product proto) {
        showcase.put(name, proto);
    }
    public Product create(String protoname) {
        Product p = (Product) showcase.get(protoname);
        return p.creatClone();
    }
}

MessageBox.java

import framework.Product;
/**
 * @Author:DarknessShadow
 * @description:
 * @date 2020/5/12 13:59
 */
public class MessageBox implements Product {
    private char docochar;
    public MessageBox(char docochar) {
        this.docochar = docochar;
    }
    @Override
    public void use(String s) {
        int length = s.getBytes().length;
        for (int i = 0; i < length + 4; i++) {
            System.out.print(docochar);
        }
        System.out.println("");
        System.out.println(docochar + " " + s + " " + docochar);
        for (int i = 0; i < length; i++) {
            System.out.print(docochar);
        }
        System.out.println("");
    }
    @Override
    public Product creatClone() {
        Product p = null;
        try {
            p = (Product) clone();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return p;
    }
}

UnderllinePen.java

import framework.Product;
/**
 * @Author:DarknessShadow
 * @description:
 * @date 2020/5/12 14:08
 */
public class UnderlinePen implements Product {
    private char ulchar;
    public UnderlinePen(char ulchar) {
        this.ulchar = ulchar;
    }
    @Override
    public void use(String s) {
        int length = s.getBytes().length;
        System.out.println("\"" + s + "\"");
        System.out.print(" ");
        for (int i = 0; i < length; i++) {
            System.out.print(ulchar);
        }
        System.out.println("");
    }
    @Override
    public Product creatClone() {
        Product p = null;
        try {
            p = (Product) clone();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return p;
    }
}

Main.java

import framework.Manager;
import framework.Product;
/**
 * @Author:DarknessShadow
 * @description:主测试程序
 * @date 2020/5/12 14:11
 */
public class Main {
    public static void main(String[] args) {
        Manager manager = new Manager();
        UnderlinePen upen = new UnderlinePen('~');
        MessageBox mbox = new MessageBox('*');
        MessageBox sbox = new MessageBox('/');
        manager.register("Strong message", upen);
        manager.register("warning box", mbox);
        manager.register("slash box", sbox);

        Product p1 = manager.create("Strong message");
        p1.use("hello , world");
        Product p2 = manager.create("warning box");
        p2.use("hello, world.");
        Product p3 = manager.create("slash box");
        p3.use("hello, world.");
    }
}

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