5 Singleton模式——只有一个实例

6 Prototype模式——通过复制生成实例

6.2 示例程序

包framework

public interface Product extends Cloneable {
    void use(String s);
    Product createClone();
}
public class Manager {
    private HashMap 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.createClone();
    }
}

product

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

使用

public class Main {
    public static void main(String[] args) {
        // 准备
        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);
        // 生成
        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.");
    }
}

6.3 Protptype模式中的角色

7 Builder模式——组装复杂的实例

8 AbstractFactory模式——抽象工厂