【java标准库系列】重学设计模式

设计模式简介

设计模式分为三种类型，共23种：

• 创建型模式
  单例模式、抽象工厂模式、建造者模式、工厂模式、原型模式。

• 结构型模式
  适配器模式、桥接模式、装饰模式、组合模式、外观模式、享元模式、代理模式。

• 行为型模式
  模版方法模式、命令模式、迭代器模式、观察者模式、中介者模式、备忘录模式、解释器模式、状态模式、策略模式、职责链模式(责任链模式)、访问者模式。

创建型模式

工厂方法模式

抽象产品类:

public abstract class Product {
    public void method1(){
    };
}

具体产品类1：

package com.jxdw.abstractfactory;

public class ConcreteProduct1 extends Product {
public void method2(){
    System.out.println("-------------------ConcreteProduct1 method2----------------");
}
}

具体产品类2：

package com.jxdw.abstractfactory;

public class ConcreteProduct2 extends Product {
    public void method2(){
        System.out.println("ConcreteProduct2 method2");
    }
}

抽象工厂类:

package com.jxdw.abstractfactory;

public abstract class Creator {
    public abstract <T extends Product> T creator(Class<T> c);
}

具体工厂类:

package com.jxdw.abstractfactory;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

public class ConcreteCreator extends Creator {

    @Override
    public <T extends Product> T creator(Class<T> c) {
        Product product=null;
        try {
            product=(Product) Class.forName(c.getName()).newInstance();
            Method method=c.getMethod("method2",null);
            method.invoke(product,null);
        } catch (InstantiationException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        }
        return (T)product;
    }
}

测试类:

package com.jxdw.abstractfactory;

public class Client {
    public static void main(String[] args){
        Creator creator=new ConcreteCreator();
        Product product=creator.creator(ConcreteProduct1.class);
        //((ConcreteProduct1) product).method2();
    }
}

结构型模式

代理模式

接口：

package com.jxdw.Proxy;

public interface IGamePlayer {
    public void login(String username,String password);
    public void killBoss();
    public void upgrade();
}

具体类：

package com.jxdw.Proxy;

public class GamePlayer implements IGamePlayer {
    private  String name="";

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

    @Override
    public void login(String username, String password) {
        System.out.println("login username: "+username+",password: "+password);
    }

    @Override
    public void killBoss() {
       System.out.println("kill boss");
    }

    @Override
    public void upgrade() {
        System.out.println("upgrade game");
    }
}

代理类

package com.jxdw.Proxy;

public class GamePlayerProxy {
    private IGamePlayer iGamePlayer;

    public GamePlayerProxy(IGamePlayer iGamePlayer) {
        this.iGamePlayer = iGamePlayer;
    }
    public void killBoss(){
        this.iGamePlayer.killBoss();
    }
    public  void upgrade(){
        this.iGamePlayer.upgrade();
    }
    public void login(String username,String password){
        this.iGamePlayer.login(username,password);
    }
}

测试类：

package com.jxdw.Proxy;

public class Client {
    public static void main(String[] args) {
        IGamePlayer gamePlayer=new GamePlayer("zhangsan");
        GamePlayerProxy gamePlayerProxy=new GamePlayerProxy(gamePlayer);
        gamePlayerProxy.login("zhangsan","password");
    }
}

行为型模式

观察者模式

观察者接口:

package com.jxdw;

public interface IObserver {
    void update(String message);
}

主题接口:

package com.jxdw;

public interface ISubject {
    void addObserver(IObserver iObserver);
    void deleteObserver(IObserver iObserver);
    void inform();
}

观察者实现:

package com.jxdw;

public class CompleteObserver implements IObserver {
    @Override
    public void update(String message) {
        System.out.println("observer receive "+message);
    }
}

主题实现:

package com.jxdw;

import java.util.Vector;

public class CompleteSubject implements ISubject {
    private Vector<IObserver> observerVector=new Vector<IObserver>();
    @Override
    public void addObserver(IObserver iObserver) {
        observerVector.add(iObserver);
    }

    @Override
    public void deleteObserver(IObserver iObserver) {
        observerVector.removeElement(iObserver);
    }

    @Override
    public void inform() {
        System.out.println("message");
        for (IObserver iObserver:observerVector){
            iObserver.update("message");
        }
    }
}

测试类:

package com.jxdw;

public class App 
{
    public static void main( String[] args )
    {
        System.out.println( "Hello World!" );
        ISubject completeSubject=new CompleteSubject();
        completeSubject.addObserver(new CompleteObserver());
        completeSubject.inform();
    }
}