设计模式

设计模式

六大原则

• 开闭原则
• 扩展性
• 易于修改
• 里式代换原则
• 依赖倒转原则
• 接口隔离原则

常见的几种设计模式

• 单例模式

  懒汉式:

  class Singleton{
  	static private Singleton singleton = null;
  	public  Singleton getSingleton() {
  		if (singleton == null) {// 第一层上锁
  			synchronized (Singleton.class) {
  				if(singleton==null) // 第二层上锁  双重检验锁
  				singleton = new Singleton();
  			}
  			
  		}
  		//当对象不是Null时候不用考虑线程安全了
  		return singleton;
  	}
  }
  

  饿汉式:

  class Singleton{
  	static private Singleton singleton = new Singleton();
  	public  Singleton getSingleton() {
  		if (singleton == null) {// 第一层上锁
  			synchronized (Singleton.class) {
  				if(singleton==null) // 第二层上锁  双重检验锁
  				singleton = new Singleton();
  			}
  			
  		}
  		//当对象不是Null时候不用考虑线程安全了
  		return singleton;
  	}
  }
  

• 工厂模式

  简单工厂:

  interface Car {void run();}
  class AoDi implements Car {
  @Override public void run() {
  		System.out.println("我是奥迪汽车---我是奥迪A6l");}}
  class BenChi implements Car {
  @Override public void run() {
  		System.out.println("我是奔驰汽车----我是奔驰E级");}}
  
  // 奔驰工厂
  class BenChiFatory {
  	static public Car createCar() {
  		return new BenChi();
  	}}
  
  class AoDiFatory {
  	static public Car createCar() {
  		return new AoDi();
  	}}
  
  class CarFatory {
  	static public Car createCar(String name) {
  		Car car = null;
  		switch (name) {
  		case "奥迪":
  			car = new AoDi();
  			break;
  		case "奔驰":
  			car = new BenChi();
  			break;
  		default:
  			break;
  		}
  		return car;
  	}
  }
  
  public class Test005 {
  	public static void main(String[] args) {
  		Car car = BenChiFatory.createCar();
  		car.run();
  		// Car car = CarFatory.createCar("奔驰");
  		// car.run();
  	}
  }
  

  抽象工厂:

• 代理模式

  静态代理:

  class YuShengJun implements Hose {
  
  	@Override
  	public void maifang() {
  		System.out.println("我是余胜军，终于可以买房啦!!!");
  	}
  
  }
  
  // 静态代理
  class Proxy implements Hose {
  	// 代理对象
  	private YuShengJun yuShengJun;
  
  	public Proxy(YuShengJun yuShengJun) {
  		this.yuShengJun = yuShengJun;
  	}
  
  	@Override
  	public void maifang() {
  		System.out.println("我是中介,你买房开始交给我啦!!!");
  		yuShengJun.maifang();
  		System.out.println("我是中介,你买房开结束啦!!!");
  	}
  
  }
  

  动态代理:

  // jdk动态代理
  class JdkProxy implements InvocationHandler {
  	private Object tarjet;
  
  	JdkProxy(Object tarjet) {
  		this.tarjet = tarjet;
  	}
  
  	@Override
  	public Object invoke(Object paramObject, Method paramMethod, Object[] paramArrayOfObject) throws Throwable {
  
  		System.out.println("我是中介,你买房开始交给我啦!!!");
  		Object invoke = paramMethod.invoke(tarjet, paramArrayOfObject);
  		System.out.println("我是中介,你买房开结束啦!!!");
  		return invoke;
  
  	}
  
  }
  
   //cglib 动态代理
  class Cglib implements MethodInterceptor{
  
  	@Override
  	public Object intercept(Object oj, Method method, Object[] arrays, MethodProxy methodProxy) throws Throwable {
  		  
  		System.out.println("我是中介,你买房开始交给我啦!!!");
  		Object invokeSuper = methodProxy.invokeSuper(oj, arrays);
  		System.out.println("我是中介,你买房开结束啦!!!");
  		 return invokeSuper;  
  		    
  	}
  	
  	
  }
  
  public class Test006 {
  	public static void main(String[] args) {
  //		Hose hose = new Proxy(new YuShengJun());
  //		hose.maifang();
  		YuShengJun yuShengJun = new YuShengJun();
  //		JdkProxy jdkProxy = new JdkProxy(yuShengJun);
  //		Hose hose = (Hose) java.lang.reflect.Proxy.newProxyInstance(yuShengJun.getClass().getClassLoader(), yuShengJun.getClass().getInterfaces(), jdkProxy);
  //		hose.maifang();
  		Cglib cglib = new Cglib();
  		Enhancer enhancer = new Enhancer();
  		enhancer.setSuperclass(YuShengJun.class);
  		enhancer.setCallback(cglib);
  		Hose hose = (Hose) enhancer.create();
  		hose.maifang();
  		
  	}
  }