Prototype(原型)

根据实例原型、实例模版来生成新的实例

java中，可以使用clone创建出实例的副本

/**
 * 原型
 */
public interface Product extends Cloneable {
    public abstract void use(String s);
    public abstract Product createClone();
}

/**
 * 具体的原型 ，负责实现复制现有实例并生成新实例
 */
public class MessageBox implements Product  {
    private char decochar;

    public MessageBox(char decochar) {
        this.decochar = decochar;
    }

    @Override
    public void use(String s) {
        int length = s.getBytes().length;
        for (int i = 0; i < length + 4; i++) {
            System.out.print(decochar);
        }
        System.out.println("");
        System.out.println(decochar+" "+s+" "+decochar);
        for (int i = 0; i < length + 4; i++) {
            System.out.print(decochar);
        }
        System.out.println("");
    }

    @Override
    public Product createClone() {
        Product p = null;
        try {
            p = (Product) clone();//Object中的clone，Product需要继承Cloneable
        } catch (CloneNotSupportedException e) {
            e.printStackTrace();
        }
        return p;
    }
}

/**
 * 具体的原型
 */
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 + 4; i++) {
            System.out.print(ulchar);
        }
        System.out.println("");
    }

    @Override
    public Product createClone() {
        Product p = null;
        try {
            p = (Product) clone();
        } catch (CloneNotSupportedException e) {
            e.printStackTrace();
        }
        return p;
    }
}

/**
 * 使用者 ，负责使用复制实例的方法生成新的实例
 */
public class Manager {
    private HashMap showcase = new HashMap();
    //使用字符串为生成的实例命名
    public void register(String name,Product proto){
        showcase.put(name,proto);
    }
    public Product create(String protoname){
        Product p = (Product) showcase.get(protoname);
        return p.createClone();
    }
}

public class Main {
    public static void main(String[] args){
        Manager manager = new Manager();
        UnderlinePen underlinePen = new UnderlinePen('~');
        MessageBox mbox = new MessageBox('*');
        MessageBox sbox = new MessageBox('/');
        manager.register("message",underlinePen);
        manager.register("warning",mbox);
        manager.register("sbox",sbox);

        Product p1 = manager.create("message");
        p1.use("hello");
        Product p2 = manager.create("warning");
        p2.use("hello");
        Product p3 = manager.create("sbox");
        p3.use("hello");
        /*
         * "hello"
         *  ~~~~~~~~~
         * *********
         * * hello *
         * *********
         * /////////
         * / hello /
         * /////////
         */
    }
}

Cloneable接口是标记可以使用clone方法的

clone方法进行的是浅复制，当字段中保存的是数组时，只会复制该数组的引用