23个设计模式C#代码

// Chain Of Responsibility // Intent: "Avoid coupling the sender of a request to its receiver by giving // more than one object a chance to handle the reuqest. Chain the receiving // objects and pass the request along the chain until an object handles it." // For further information, read "Design Patterns", p223, Gamma et al., // Addison-Wesley, ISBN:0-201-63361-2 /* Notes: * The client sends a request and it will be operated on by one of a number * of potential receivers, in a chain. The client does not know (and does * not need to know) which receiver handles the request. The receivers are * in a chain, and the request is passed from one to the next, until one * receiver actually performs the request. */ namespace ChainOfResponsibility_DesignPattern { using System; abstract class Handler { protected Handler successorHandler; abstract public void HandleRequest(Request request); public void SetSuccessor(Handler sucessor) { successorHandler = sucessor; } } class ConcreteHandler1 : Handler { override public void HandleRequest(Request request) { // determine if we can handle the request if (request.RequestType == 1) // some complex decision making! { // request handling code goes here Console.WriteLine("request handled in ConcreteHandler1"); } else { // not handled here - pass on to next in the chain if (successorHandler != null) successorHandler.HandleRequest(request); } } } class ConcreteHandler2 : Handler { override public void HandleRequest(Request request) { // determine if we can handle the request if (request.RequestType == 2) // some complex decision making! { // request handling code goes here Console.WriteLine("request handled in ConcreteHandler2"); } else { // not handled here - pass on to next in the chain if (successorHandler != null) successorHandler.HandleRequest(request); } } } class ConcreteHandler3 : Handler { override public void HandleRequest(Request request) { // determine if we can handle the request if (request.RequestType == 3) // some complex decision making! { // request handling code goes here Console.WriteLine("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 RequestType { get { return iRequestType; } set { iRequestType = value; } } } /// <summary> /// Summary description for Client. /// </summary> public class Client { public static int 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); return 0; } } }