client.java

设计模式描述设计模式描述设计模式描述设计模式描述

/*
 * Created on 2005-5-11
 *
 * TODO To change the template for this generated file go to
 * Window - Preferences - Java - Code Style - Code Templates
 */
package com.test.pattern.behavir.chain;

/**
 * @author Administrator
 * 
 * 意图 使多个对象都有机会处理请求，从而避免请求的发送者和接收者之间的耦合关系。将这些对象连成一条链，并沿着这条链传递该请求，直到有一个对象处理它为止。
 * 适用性 有多个的对象可以处理一个请求，哪个对象处理该请求运行时刻自动确定。 你想在不明确指定接收者的情况下，向多个对象中的一个提交一个请求。
 * 可处理一个请求的对象集合应被动态指定。
 *  
 */
abstract class Handler {
	protected Handler successorHandler;

	abstract public void HandleRequest(Request request);

	public void SetSuccessor(Handler sucessor) {
		successorHandler = sucessor;
	}
}

class ConcreteHandler1 extends Handler {
	public void HandleRequest(Request request) {
		// determine if we can handle the request
		if (request.getRequestType() == 1) // some complex decision making!
		{
			// request handling code goes here
			System.out.println("request handled in ConcreteHandler1");
		} else {
			// not handled here - pass on to next in the chain
			if (successorHandler != null)
				successorHandler.HandleRequest(request);
		}
	}
}

class ConcreteHandler2 extends Handler {
	public void HandleRequest(Request request) {
		// determine if we can handle the request
		if (request.getRequestType() == 2) // some complex decision making!
		{
			// request handling code goes here
			System.out.println("request handled in ConcreteHandler2");
		} else {
			// not handled here - pass on to next in the chain
			if (successorHandler != null)
				successorHandler.HandleRequest(request);
		}
	}
}

class ConcreteHandler3 extends Handler {
	public void HandleRequest(Request request) {
		// determine if we can handle the request
		if (request.getRequestType() == 3) // some complex decision making!
		{
			// request handling code goes here
			System.out.println("request handled in ConcreteHandler3");
		} else {
			// not handled here - pass on to next in the chain
			if (successorHandler != null)
				successorHandler.HandleRequest(request);
		}
	}
}

class Request {
	private int iRequestType;

	private String strRequestParameters;

	public Request(int requestType, String requestParameters) {
		iRequestType = requestType;
		strRequestParameters = requestParameters;
	}

	public int getRequestType() {
		return iRequestType;
	}

	public void setRequestType(int value) {
		iRequestType = value;
	}
}

/// <summary>
/// Summary description for Client.
/// </summary>

public class Client {
	public static void main(String[] args) {
		// Set up chain (usually one need to be done once)
		Handler firstHandler = new ConcreteHandler1();
		Handler secondHandler = new ConcreteHandler2();
		Handler thirdHandler = new ConcreteHandler3();
		firstHandler.SetSuccessor(secondHandler);
		secondHandler.SetSuccessor(thirdHandler);

		// After setting up the chain of responsibility, we can
		// now generate requests and pass then off to the
		// chain to be handled

		// generate and fire request
		Request newRequest = new Request(2, "This are the request parameters");
		firstHandler.HandleRequest(newRequest);

	}
}