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Xiaobian to share with you how to use MessageHandler in WeChat public platform development, I hope you have something to gain after reading this article, let's discuss it together!

Continue by adding a CustomMessageHandle.cs class to your project:

CustomMessageHandle.cs needs to inherit the abstract class Senparc.Weixin.MP.MessageHandlers and implement some methods. The rudimentary CustomMessageHandle.cs code

It may be as follows:

using System;using System.Collections.Generic;using System.IO;using System.Linq;using System.Web;using Senparc.Weixin.MP.Entities;using Senparc.Weixin.MP.MessageHandlers; namespace Senparc.Weixin.MP.Sample.Weixin{ public class CustomMessageHandler : MessageHandler { public CustomMessageHandler(Stream inputStream, PostModel postModel) : base(inputStream, postModel) { } public override IResponseMessageBase DefaultResponseMessage(IRequestMessageBase requestMessage) { var responseMessage = base.CreateResponseMessage(); //ResponseMessageText can also be News and other types responseMessage.Content = "This message is from DefaultResponseMessage. "; return responseMessage; } }}

We can see that the abstract method that must be rewritten is called DefaultResponseMessage(), which is used to return a message. If the WeChat message of the corresponding type (such as voice) is not processed by the code, then the default will return the result here.

In the DefaultResponseMessage() method, we see this sentence:

var responseMessage = base.CreateResponseMessage(); //ResponseMessageText can also be News and other types

The CreateResponseMessage method here creates a return object. T can be any of the following types, corresponding to different return types:

ResponseMessageText -Corresponding text message

ResponseMessageNews

ResponseMessageMusic -corresponding music message

ResponseMessageXXX -other types and so on

For the setting methods of all the above types of parameters, you can see the Demo of the open source project, which is not repeated here: https://github.com/JeffreySu/WeiXinMPSDK.

So how do we handle text messages sent by users?

It's simple-rewrite an OnTextRequest method:

public override IResponseMessageBase OnTextRequest(RequestMessageText requestMessage){ var responseMessage = base.CreateResponseMessage(); responseMessage.Content = "Your OpenID is: " + requestMessage.FromUserName //requestMessage.FromUserName here can also be written directly as base.WeixinOpenId + "。\ r\nYou sent a text message: " + requestMessage.Content; //\r\nUsed for newline, requestMessage.Content is the text content sent by the user. return responseMessage;}

This method can be used freely, such as reading the database, judging keywords, and even returning different ResponseMessageXX types (as long as the final types are under the IResponseMessageBase interface).

Corresponding to OnTextRequest, if we want to process voice, geographical location, menu and other types of messages, we only need to rewrite the corresponding method, which can be rewritten as follows:

public virtual IResponseMessageBase OnImageRequest(RequestMessageImage requestMessage); public virtual IResponseMessageBase OnLinkRequest(RequestMessageLink requestMessage); public virtual IResponseMessageBase OnLocationRequest(RequestMessageLocation requestMessage); public virtual IResponseMessageBase OnTextRequest(RequestMessageText requestMessage); public virtual IResponseMessageBase OnVoiceRequest(RequestMessageVoice requestMessage); public virtual IResponseMessageBase OnVideoRequest(RequestMessageVideo requestMessage); public virtual IResponseMessageBase OnEvent_ClickRequest(RequestMessageEvent_Click requestMessage); public virtual IResponseMessageBase OnEvent_ViewRequest(RequestMessageEvent_View requestMessage); public virtual IResponseMessageBase OnEvent_EnterRequest(RequestMessageEvent_Enter requestMessage); public virtual IResponseMessageBase OnEvent_LocationRequest(RequestMessageEvent_Location requestMessage); public virtual IResponseMessageBase OnEvent_SubscribeRequest(RequestMessageEvent_Subscribe requestMessage); public virtual IResponseMessageBase OnEvent_UnsubscribeRequest(RequestMessageEvent_Unsubscribe requestMessage); public virtual IResponseMessageBase OnEvent_ScanRequest(RequestMessageEvent_Scan requestMessage) public virtual IResponseMessageBase OneEvent_MassSendJobFinisRequest(RequestMessageEvent_MassSendJobFinish requestMessage)

OnEvent_XX is a subtype of Event Request.

When setting the base class of CustomMessageHandler, we see that a generic called MessageContext is used. This MessageContext is a default message context processing class provided by the SDK. This class can already handle the most basic situations. If your application is not very complex, then you can use this class directly. If the project is more complex, you can also write your own class (inheriting the IMessageContext interface), or inherit this class to extend some more properties (such as workflow and distributed caching, etc.) according to your needs.

So far we have used MassageHandler to process all requests sent by WeChat users.

Here are some of MassageHandler's "secret weapons."

OnExecuting() and OnExecuted()

We can rewrite both methods directly. OnExecuting will be executed before all message processing methods (such as OnTextRequest, OnVoiceRequest, etc.) are executed. In this process, we can set CancelExecute to true to interrupt the execution of all subsequent methods (including OnExecuted). For example:

public override void OnExecuting(){ if (RequestMessage.FromUserName == "olPjZjsXuQPJoV0HlruZkNzKc91E") { CancelException = true; //Terminate this user's conversation //If there is no code below, the user will not receive any reply because ResponseMessage is null. //add a fixed reply var responseMessage = CreateResponseMessage(); responseMessage.Content = "Hey! You've been blocked! "; ResponseMessage = responseMessage;//Set the returned object }}

If there is no interrupt in OnExecuting, the OnExecuted() method will fire when, for example, the OnTextRequest method finishes executing (or the default method is executed), and we can override it accordingly. Note that within the OnExecuted() method, ResponseMessage has been assigned a return value.

After reading this article, I believe you have a certain understanding of "how to use MessageHandler in WeChat public platform development." If you want to know more about relevant knowledge, please pay attention to the industry information channel. Thank you for reading!

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