模式-“里氏替换原则”

Context   

/**
 * 	@author Lean  @date:2014-10-17  
 */
public class Context {

	public static Strategy strategy;
	
	public static void main(String[] args) {
		strategy=new ConcreteStrategyA();
		strategy.calculate();
	}
	
}

abstract class Strategy{
	
	public abstract void calculate();
	
}

class ConcreteStrategyA extends Strategy{

	@Override
	public void calculate() {
		System.out.println("ConcreteStrategyA is called !");
	}
	
}

class ConcreteStrategyB extends Strategy{
	
	@Override
	public void calculate() {
		System.out.println("ConcreteStrategyB is called !");
	}
	

IChoiceStrategy

/**
 * 		选择策略
 * 
 * 	@author Lean  @date:2014-10-17  
 */
public abstract class IChoiceStrategy {

	/**
	 * @return	返回列表名字
	 */
	public abstract String[] getNames();
	
	/**
	 * @return	返回相应码
	 */
	public abstract int getCode(String name);
	
}

/**
 * 	@author Lean  @date:2014-10-17  
 */
public class SortChoiceStrategy extends IChoiceStrategy {
	
	private HashMap<String, Integer> mSortMap;
	public String name;
	
	public SortChoiceStrategy() {
		initSortMap();
	}

	private void initSortMap() {
		mSortMap=new HashMap<String, Integer>();
		mSortMap.put("最新上架", 0);
		mSortMap.put("销量最高", 1);
		mSortMap.put("价格最高", 2);
		mSortMap.put("价格最低", 3);
		name="最新上架";
	}

	@Override
	public String[] getNames() {
		Set<String> set=mSortMap.keySet();
		Object[] tempObj=set.toArray();
		String[] result=new String[tempObj.length];
		for (int i = 0; i < tempObj.length; i++) {
			result[i]=(String) tempObj[i];
		}
		return result;
	}

	@Override
	public int getCode(String name) {
		return mSortMap.get(name);
	}

}

/**
 * 	@author Lean  @date:2014-10-17  
 */
public class StatusChoiceStrategy extends IChoiceStrategy {
	
	private HashMap<String, Integer> mStatusMap;
	public String name;
	
	public StatusChoiceStrategy() {
		initStatusMap();
	}
	
	private void initStatusMap() {
		mStatusMap=new HashMap<String, Integer>();
		mStatusMap.put("定制中", 1);
		mStatusMap.put("已完毕", 2);
		name="定制中";
	}

	@Override
	public String[] getNames() {
		Set<String> set=mStatusMap.keySet();
		Object[] tempObj=set.toArray();
		String[] result=new String[tempObj.length];
		for (int i = 0; i < tempObj.length; i++) {
			result[i]=(String) tempObj[i];
		}
		return result;
	}

	@Override
	public int getCode(String name) {
		return mStatusMap.get(name);
	}

}

拦截,如打印日志;(像这样的利用中间层来达到目的的模式还有适配器模式)

/**
 * 	@author Lean  @date:2014-10-17  
 */
public abstract class IPerson {
	
	public abstract void buyTicket();
	
}

/**
 * 	@author Lean  @date:2014-10-17  
 */
public class RealSeePerson extends IPerson {

	@Override
	public void buyTicket() {
		System.out.println("RealSeePerson get the ticket !");
	}

}

/**
 * 	@author Lean  @date:2014-10-17  
 */
public class BuyTicketPerson extends IPerson{
	
	public RealSeePerson target;
	
	private void preBuyTicket(){
		//TODO do th. before buy ticket
		target=new RealSeePerson();
	}
	
	@Override
	public void buyTicket() {
		preBuyTicket();
		if (target!=null) {
			target.buyTicket();
		}
		postBuyTicket();
	}
	
	public void postBuyTicket(){
		//TODO do th. after buy thicket
	}
	
}

>代理和被代理对象实现共同接口,代理对象被调用时调用被代理对象的托付;

动态代理实现监听：

/**
 * 	@author Lean  @date:2014-10-17  
 */
public class VectorProxy implements InvocationHandler {
	
	private Object proxyobj;
	
	public VectorProxy(Object obj) {
		proxyobj=obj;
	}
	
	public static Object factor(Object obj){
		Class cls=obj.getClass();
		return Proxy.newProxyInstance(cls.getClassLoader(),cls.getInterfaces(),new VectorProxy(obj));
	}
	
	@Override
	public Object invoke(Object proxy, Method method, Object[] args)
			throws Throwable {
		System.out.println("method:"+method.getName());
		if (args!=null) {
			for (int i = 0; i < args.length; i++) {
				System.out.println(args[i]+"");
			}
		}
		//反射调用
		Object obj=method.invoke(proxyobj, args);
		System.out.println("*********");
		return obj;
	}
	
	public static void main(String[] args) {
		List v=null;
		//返回代理对象,并调用代理对象的add方法
		v=(List) factor(new Vector(10));
		v.add("New");
	}
	

}

合成模式分为透明式和安全式

透明：指抽象接口声明了枝叶全部的全部接口方法，在叶子类中。对该方法进行空实现；

/**
 * 	@author Lean  @date:2014-10-20  
 */
public interface Component {
	
	void sampleOperation();

	Composite getComposite();
	
	void add(Component component);
	
	void remove(Component component);
	
	Enumeration<Component> components();
	
}

/**
 * 	@author Lean  @date:2014-10-20  
 */
public class Composite implements Component {
	
	private Vector<Component> componentVector=new Vector<Component>();
	
	@Override
	public Composite getComposite() {
		return this;
	}

	@Override
	public void sampleOperation() {
		Enumeration<Component> enumeration=components();
		while (enumeration.hasMoreElements()) {
			Component component = (Component) enumeration.nextElement();
			component.sampleOperation();
		}
	}

	@Override
	public void add(Component component) {
		componentVector.addElement(component);
	}

	@Override
	public void remove(Component component) {
		componentVector.removeElement(component);
	}

	@Override
	public Enumeration<Component> components() {
		return componentVector.elements();
	}

}

/**
 * 	@author Lean  @date:2014-10-20  
 */
public class Leaf implements Component {

	@Override
	public Composite getComposite() {
		return null;
	}

	@Override
	public void sampleOperation() {
		System.out.println(" call leaf here !");
	}

	@Override
	public void add(Component component) {
		
	}

	@Override
	public void remove(Component component) {
		
	}

	@Override
	public Enumeration<Component> components() {
		return null;
	}

}

安全：指抽象接口仅仅声明叶子全部的方法，树枝类除了继承还包含了自己的管理叶子类方法；典型应用：Android的View,ViewGroup

/**
 * 	@author Lean  @date:2014-10-20  
 */
public interface Component {

	Composite getComposite();
	
	void sampleOperation();
	
}

/**
 * 	@author Lean  @date:2014-10-20  
 */
public class Composite implements Component {
	
	private Vector componentVector=new Vector();
	
	@Override
	public void sampleOperation() {
		Enumeration enumeration=components();
		while (enumeration.hasMoreElements()) {
			((Component) enumeration.nextElement()).sampleOperation();
		}
	}

	@Override
	public Composite getComposite() {
		return this;
	}
	
	public Enumeration components(){
		return componentVector.elements();
	}
	
	public void add(Component component){
		componentVector.addElement(component);
	}
	
	public void remove(Component component){
		componentVector.removeElement(component);
	}
	
}

/**
 * 	@author Lean  @date:2014-10-20  
 */
public class Leaf implements Component {

	@Override
	public Composite getComposite() {
		return null;
	}

	@Override
	public void sampleOperation() {
		System.out.println("leaf is called !");
	}

}

由于分支机构基本继承抽象类，在抽象方法只支持类，那里可以换成一个叶子。例如，在安全模式。叶类可以换成棒/多叶；在透明模式下可以互换。这是与里氏代换原则；