Source code analysis of senparc.weixin.sample.mp

  Senparc.Weixin.Sample.MP It is a sample of wechat official account .NET6 Source code , Project profile appsettings.json And the construction of wechat official account test environment ： Wechat official account debugging and Natapp Environment building . Next, from the project structure , Project application and project source code 3 Explain from different angles .

One . From the perspective of project structure

The overall structure of the project code is as follows ： The key part is MessageHandlers Message processor section , Include message context 、 Message processor and event processor . After the project is started, the interface is ：

Two . Application angle

1. The intuitive process of data flow

First of all, understand the wechat client 、 Wechat servers and third-party websites 3 The data flow relationship between , Let's introduce the process of data flow by taking the text sent by the user as an example ：

• Users send... Through wechat client OpenId

• The wechat server sends the text to the third-party website . Of course, if there is no third-party website , That is to say, there is no secondary development of official account , Then the user will not get any response message

• Third party websites process messages , For example, get the user's OpenId Etc

• The third-party website returns the processed message to the wechat server

• Wechat server forwards messages from third-party websites to wechat clients

• In this way, the user will receive a message from the wechat client The message types of wechat mainly include request messages and response messages , The request message is the message sent by the wechat server to the website , The response message is the message sent by the website to the wechat server . The specific request message and response message contain the following types ：

2. Code process of data flow

(1) Official account message simulator
The input and output contents of official account message simulator are as follows ：

• URL： adopt Natapp Mapped domain names , namely http://fengling.nat300.top -> 127.0.0.1:8080.

• Token、AppId and AESKey： Reference resources appsettings.json file .

• type ： Text 、 Location 、 picture 、 voice 、 video 、 Time push .

• Content ：OPENID. The text message processor processes the text .

(2)Post(PostModel postModel) Method
After the user sends a message , Wechat platform automatic Post A request to method public async TaskPost(PostModel postModel), And wait for a response XML： In this method, you can customize MessageHandler To deal with ：

var messageHandler = new CustomMessageHandler(await Request.GetRequestMemoryStreamAsync(), postModel, maxRecordCount);

The real wechat processing method is ：

public async Task ExecuteAsync(CancellationToken cancellationToken)

(3)OnTextRequestAsync(RequestMessageText requestMessage) Method
This method can respond according to the input text , It can be matching keywords 、 Regular expressions 、 Don't reply , Or default response .

3、 ... and . Source angle

1.Program.cs Code

First of all Senparc.Weixin SDK Relevant codes of overall registration ：

//  To use local caching, you must add 
builder.Services.AddMemoryCache();
// Senparc.Weixin  register （ must ）
builder.Services.AddSenparcWeixinServices(builder.Configuration);
...
var senparcWeixinSetting = app.Services.GetService<IOptions<SenparcWeixinSetting>>()!.Value;
// Enable wechat configuration （ must ）
var registerService = app.UseSenparcWeixin(app.Environment,
    null /* Not for null Coverage appsettings Medium SenpacSetting To configure */,
    null /* Not for null Coverage appsettings Medium SenpacWeixinSetting To configure */,
    register => { /*CO2NET Global configuration */ },
    (register, weixinSetting) =>
    {
        // Register official account information （ It can be executed multiple times , Register multiple official account ）
        register.RegisterMpAccount(weixinSetting, "XXX official account ");
    });  
......
//  Using official account MessageHandler middleware （ There is no need to create Controller）  
app.UseMessageHandlerForMp("/WeixinAsync", CustomMessageHandler.GenerateMessageHandler, options =>
{
    options.AccountSettingFunc = context => Senparc.Weixin.Config.SenparcWeixinSetting;
});

(1)builder.Services.AddMemoryCache()
The framework supports memory caching 、Redis、Memcached And other caching strategies .
(2)builder.Services.AddSenparcWeixinServices(builder.Configuration)
Realization Senparc.Weixin Registration of .
(3)app.UseSenparcWeixin()
This method integrates CON2ET Global registration and Senparc.Weixin SDK Wechat registration process .
(4)app.UseMessageHandlerForMp
Use MessageHandler To configure , The asynchronous method will be used by default messageHandler.ExecuteAsync().

2.WeixinController.cs Code

(1)public ActionResult Get(PostModel postModel, string echostr)
This method is mainly used for wechat background address verification , It's not used at other times .
(2)public async Task<ActionResult> Post(PostModel postModel)
This method is to forward messages by wechat server [XML] To website , Wait for the website to process and return the message [XML] The process of sending to wechat server .
(3)messageHandler.OmitRepeatedMessage = true;

• When the website cannot respond to the request of wechat server in time , Wechat server will continuously send multiple identical MsgId Message to the website , To prevent packet loss . This situation requires the use of MsgId De duplicate the news , Otherwise, the website will execute the same request many times .

• It should be noted that , For multiple lines with the same MsgId Reply multiple times to the request message of , The client can only receive the response message corresponding to the last retransmission of the wechat server .

(4)messageHandler.DefaultMessageHandlerAsyncEvent = DefaultMessageHandlerAsyncEvent.SelfSynicMethod;
When the synchronization method is overridden , And the asynchronous method is not overridden , Try calling the synchronization method .

3.CustomMessageContext.cs Code

(1)CustomMessageContext
CustomMessageContext Is the context of the message , The writing method is basically fixed , You can use it by moving it directly . The message context is used to record the messages sent by a single user 、 Record of received messages , Even if different wechat official account send different messages at the same time , There will be no interference between the two , Because the context of the two is completely isolated .
(2)CustomMessageContext_MessageContextRemoved
When the context expires , The time triggered when it is removed . according to WeixinContext Algorithm in , The expired messages here will be cleared before the next request is executed after expiration .

4.CustomMessageHandler.cs Code

CustomMessageHandler and CustomMessageHandler_Events yes CustomMessageHandler Class 2 Partial classes , The former deals with non event type messages , For example, send text 、 Image, etc , The latter deals with event type messages , For example, click event 、 Subscription events （ Subscribe and unsubscribe ） etc. . The request messages here are all ordinary messages ：

5.CustomMessageHandler_Events.cs Code

All the request messages here are event push messages , Event push messages are divided into 3 Large type ： Routine events [ Official account basic function return event ], Menu events [ Various types of official account menu return events ], Application events [ The application module returns an event ]：

reference ：
[1]Senparc.Weixin.Sample.MP.sln：WeiXinMPSDK\Samples\MP\Senparc.Weixin.Sample.MP.sln
[2]Senparc.Weixin SDK Source code ：https://github.com/JeffreySu/WeiXinMPSDK
[3]Senparc.Weixin.MP SDK Wechat public platform development course （ 23 ）： stay .NET Core 2.0/3.0 Use in MessageHandler middleware ：https://www.cnblogs.com/szw/p/Wechat-MessageHandler-Middleware.html
[4] Wechat development depth analysis ： official account 、 Efficient development of small programs ：http://book.weixin.senparc.com/BookHelper
[5] Wechat public platform interface debugging tool ：https://mp.weixin.qq.com/debug

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