大话设计模式(3) --- 装饰者模式|代理模式|工厂方法模式|原型模式

1. 装饰者模式

装饰模式，动态地给一个对象添加一些额外的职责，就增加功能来说，装饰模式比生成子类更加灵活，当频繁的继承使我们的代码成一条线的时候，或许就该考虑，怎么样在运行的时候扩展类的属性，或者说是装饰类，而不仅仅是在编译前期直接构思好继承逻辑。

装饰者模式

• 如果只有一个ConcreteComponent类而没有抽象的Component类，那么Decorator类可以是ConcreteComponent类的子类
• 如果只有一个ConcreteDecorator，那么也不需要Decorator类了

public class Person {
    public Person() {

    }

    private String name;
    private int age;

    public int getAge() {
        return age;
    }

    public String getName() {
        return name;
    }

    public void setAge(int age) {
        this.age = age;
    }

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

    public void show() {
        System.out.println("this is " + this.name);
    }
}

public class Clothes extends Person {
    protected Person component;

    public void Decorate(Person component) {
        this.component = component;
    }

    @Override
    public void show() {
        super.show();
        if(component != null) {
            System.out.println(component.toString());
        }
    }
}

public class TShirt extends Clothes {
    @Override
    public void Decorate(Person component) {
        super.Decorate(component);
    }

    @Override
    public void show() {
        super.show();
        System.out.println("这是T恤");
    }
}

public class Swearter extends Clothes {
    @Override
    public void show() {
        super.show();
        System.out.println("毛衣");
    }
}

public class DecoratorClient {

    public static void main(String[] args) {
        Person guanzihan = new Person();
        guanzihan.setName("guanzihan");
        guanzihan.setAge(20);
        Swearter swearter = new Swearter();
        TShirt tShirt = new TShirt();
        swearter.Decorate(guanzihan);
        tShirt.Decorate(swearter);
        tShirt.show();
    }
}

2. 代理模式

代理模式为其他对象提供一种代理以控制对这个对象的访问

代理模式

public interface SendGift {
    public void sendCake();
    public void sendFruit();
}

public class Pursuit implements SendGift {
    Girl mGirl;

    public Pursuit(Girl girl) {
        mGirl = girl;
    }
    @Override
    public void sendCake() {
        System.out.println("追求者送了蛋糕");
    }

    @Override
    public void sendFruit() {
        System.out.println("追求者送了水果");
    }
}

public class MyProxy implements SendGift {

    Pursuit mPursuit;

    public MyProxy(Girl girl) {
        mPursuit = new Pursuit(girl);
    }

    @Override
    public void sendCake() {
        System.out.println("代理送了蛋糕");
    }

    @Override
    public void sendFruit() {
        System.out.println("代理送了水果");
    }
}

public class Girl {
    String name;

    public Girl(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }

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

public class ProxtClient {
    public static void main(String[] args) {
        Girl girl = new Girl("小美");
        MyProxy proxy = new MyProxy(girl);
        proxy.sendCake();
        proxy.sendFruit();
    }
}

代理模式

3. 工厂方法模式

工厂方法模式定义了一个用于创建对象的接口，让子类决定实例化哪一个类。工厂方法使一个类的实例化延迟到其他子类

工厂方法模式

• 简单工厂模式的最大优点在于工厂类中包含了必要的逻辑判断，根据客户端的选择条件动态实例化相关的类，但是当新需求来的时候违背了开放-封闭原则
• 工厂方法模式把简单的内部逻辑判断移动到了客户端代码中进行。想要加功能，只需要修改客户端

public abstract class LeiFeng {
    public abstract void Sweep();
    public abstract void Wash();
    public abstract void BuyRice();
}

public class Undergraduate extends LeiFeng {
    @Override
    public void Sweep() {
        System.out.println("I'm sweeping the floor");
    }

    @Override
    public void Wash() {
        System.out.println("I'm washing the dishes");
    }

    @Override
    public void BuyRice() {
        System.out.println("I'm buying rice");
    }
}

public interface LeiFengFactory {
    LeiFeng createLeiFeng();
}

public class UndergraduateFactory implements LeiFengFactory {
    @Override
    public LeiFeng createLeiFeng() {
        return new Undergraduate();
    }
}

public class FactoryMethodClient {
    public static void main(String[] args) {
        LeiFengFactory leiFengFactory = new UndergraduateFactory();
        LeiFeng leiFeng = leiFengFactory.createLeiFeng();
        leiFeng.BuyRice();
        leiFeng.Sweep();
        leiFeng.Wash();
    }
}

4. 原型模式

原型模式，用原型实例指定创建对象的种类，并且通过拷贝这些原型创建新的对象

• 原型模式其实就是从一个对象再创建另一个可定制的对象，而且不需要知道任何创建的细节

原型模式

public class Resume implements Cloneable {
    private String name;
    private int age;

    public String getName() {
        return name;
    }

    public int getAge() {
        return age;
    }

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

    public void setAge(int age) {
        this.age = age;
    }

    public void Display() {
        System.out.println("My name is " + name);
        System.out.println("My age is " + age);
    }

    public Object Clone() {
        try {
            return this.clone();
        } catch (CloneNotSupportedException e) {
            e.printStackTrace();
            return null;

        }
    }
}

public class ResumeClient {
    public static void main(String[] args) {
        Resume resume = new Resume();
        resume.setAge(20);
        resume.setName("官子寒");
        resume.Display();
        Resume resumeClone = (Resume) resume.Clone();
        resumeClone.Display();
        resumeClone.setName("胡梦萱");
        resumeClone.Display();
        resume.Display();
    }
}

原型模式