Plot C#_ Events

Overview

Today's example of a demo event is a simulation implementation of a file download class in which I define a download event that is used to send a message to the user subscribing to the event during a file download, and this message is encapsulated with the Downloadeventargs class. This message class defines a percent field, which is used to save the percentage of the currently downloaded file, please crossing the appreciation process below:

First, define the message class to be sent to the user (subscribing to the event)

1     Internal classDownloadeventargs:eventargs2     {3         Private ReadOnlyInt32 _percent;//File Download Percentage4          PublicDownloadeventargs (Int32 percent)5         {6_percent =percent;7         }8 9          PublicInt32 PercentTen         { One             Get A             { -                 return_percent; -             } the         } -}

Second, the definition of file download class

This class defines a download event, a method that notifies the user (the event subscriber) when an event occurs onfiledownloaded, a file download method FileDownload, as follows:

1 Internal classFileManager2     {3          Public EventEventhandler<downloadeventargs> DownLoad;//Defining Events4 5                 6         protected Virtual voidonfiledownloaded (Downloadeventargs e)7         {8eventhandler<downloadeventargs> temp =DownLoad;9             if(Temp! =NULL)Ten             { OneTemp This, e); A             } -         } -  the          Public voidFileDownload (stringURL) -         { -             intPercent =0; -              while(Percent <= -) +             { -                 //Simulation Download File +++percent; ADownloadeventargs e =NewDownloadeventargs (percent); atOnfiledownloaded (e);//event firing, sending messages to Subscribers (values for download percentages) -  -Thread.Sleep ( +); -             } -         } -}

III. Client Subscription Events

In the client instantiation file download class, and then bind the event, as follows:

1     class Program2     {3         Static voidMain (string[] args)4         {5FileManager Manager =NewFileManager (); 6Manager. DownLoad + = Manager_download;//Subscribe to Events7Manager. FileDownload ("Http://asdfwqerqasdfs.zip");//Download File8         }9 Ten         /// <summary> One         ///methods to be executed after receiving an event notification A         /// </summary> -         /// <param name= "Sender" >Event Trigger Object</param> -         /// <param name= "E" >message sent over by event (percentage)</param> the         Private Static voidManager_download (Objectsender, Downloadeventargs e) -         { -Console.WriteLine (string. Format ("file downloaded: {0}%", E.percent.tostring ())); -         } +}

Iv. Display of results

V. Illustrations

Vi. Personal Understanding

In fact, the event is to bind a series of subscription methods on a delegate, when the method executes, when the event is triggered, the notification is bound to the method on the delegate to execute.

Summarize

Blogging is not easy, especially for me such a new C #, if you feel that the writing is OK, please praise or reward support, I will work harder to write the article.

Plot C#_ Events