微信公眾平臺開發學習系列（二）：微信公眾平臺接收消息與發送消息

本篇主要介紹如何使用senparc來處理微信公眾平臺的接收消息與發送消息。

首先微信端會將用戶的發送的信息以post請求發送到填寫的url上，服務端代碼如下：

1         [HttpPost]
2         public ActionResult Get(PostModel postModel)
3         {
4             var messageHandler = new CustomMessageHandler(Request.InputStream, postModel);
5 
6             messageHandler.Execute();//執行微信處理過程
7 
8             return Content(messageHandler.ResponseDocument.ToString());
9         }

新建一個CustomMessageHandler類和一個CustomMessageContext類，CustomMessageHandler類繼承MessageHandler<CustomMessageContext>，CustomMessageContext類繼承MessageContext<IRequestMessageBase,IResponseMessageBase>，CustomMessageContext類的方法此處不貼出，主要是實現CustomMessageHandler類的方法，代碼如下：

 1         public CustomMessageHandler(Stream inputStream, PostModel postModel)
 2             : base(inputStream, postModel)
 3         {
 4 
 5         }
 6 
 7         public override IResponseMessageBase DefaultResponseMessage(IRequestMessageBase requestMessage)
 8         {
 9             var responseMessage = base.CreateResponseMessage<ResponseMessageText>(); //ResponseMessageText指返迴文本信息
10             responseMessage.Content = "這條消息來自DefaultResponseMessage。"+requestMessage.MsgId;
11             return responseMessage;
12         }

返回信息的格式多種多樣，如：ResponseMessageText，ResponseMessageNews，ResponseMessageImage等。接收信息的格式也分很多種，不同格式有不同的處理方法：OnTextRequest，OnImageRequest,OnEvent_ViewRequest等。如果沒有重寫相應方法，就預設執行DefaultResponseMessage方法。本篇重寫2個方法作為簡單的例子。

用戶發送文本信息情況下的返回信息處理

1         public override IResponseMessageBase OnTextRequest(RequestMessageText requestMessage)
2         {
3             var responseMessage = base.CreateResponseMessage<ResponseMessageText>();
4             responseMessage.Content = "您的OpenID是：" + requestMessage.FromUserName     
5                                     + "。\r\n您發送了文字信息：" + requestMessage.Content; 
6             return responseMessage;
7         }

菜單點擊事件情況下的返回信息處理

 1         public override IResponseMessageBase OnEvent_ClickRequest(RequestMessageEvent_Click requestMessage)
 2         {
 3             IResponseMessageBase reponseMessage = null;
 4             //菜單點擊，需要跟創建菜單時的Key匹配
 5             switch (requestMessage.EventKey)
 6             {
 7                 case "OneClick":
 8                     {
 9                         var strongResponseMessage = CreateResponseMessage<ResponseMessageNews>();
10                         reponseMessage = strongResponseMessage;
11                         strongResponseMessage.Articles.Add(new Article()
12                         {
13                             Title = "您點擊了菜單圖文按鈕",
14                             Description = "您點擊圖文鏈接按鈕，這是一條圖文信息。",
15                             PicUrl = "https://ss2.baidu.com/6ONYsjip0QIZ8tyhnq/it/u=3233073314,694013259&fm=58&s=39C718720E8EBE011B398BAC0300F024",
16                             Url = "http://www.baidu.com"
17                         });
18                     }
19                     break;
20                 case "SubClickRoot_Text":
21                     {
22                         var strongResponseMessage = CreateResponseMessage<ResponseMessageText>();
23                         reponseMessage = strongResponseMessage;
24                         strongResponseMessage.Content = "您點擊了子菜單按鈕。";
25                     }
26                     break;
27                 default:
28                     {
29                         var strongResponseMessage = CreateResponseMessage<ResponseMessageText>();
30                         strongResponseMessage.Content = "您點擊了按鈕，EventKey：" + requestMessage.EventKey;
31                         reponseMessage = strongResponseMessage;
32                     }
33                     break;
34             }
35 
36             return reponseMessage;
37         }