Multi-process backgroundworker

 

Note: In this example, we will learn more about the workerreportsprogress, workersuppscanscancdllation attributes, and dowork, proesschanged, and runworkercompleted events of backgroundworker.

 

 1     Public   Partial   Class  Form1: Form  2   {  3           Public  Form1 ()  4  {  5   Initializecomponent ();  6   7               //  Gets or sets a value that indicates whether the BW report can report progress updates.  8 Backgroundworker1.workerreportsprogress = True  ;  9               //  Gets or sets a value that indicates whether BW supports asynchronous cancellation.  10 Backgroundworker1.workersuppscanscancellation =True  ;  11 Buttonstop. Enabled = False  ;  12   }  13   14           Private   Void Buttonstart_click ( Object  Sender, eventargs E)  15   {  16 Richtextbox1.text = "  Starting to generate a random number of less than 10000 ...... \ N  "  ;  17 Buttonstart. Enabled = False  ;  18 Buttonstop. Enabled = True  ;  19               //  Start operations in the background  20  Backgroundworker1.runworkerasync ();  21   }  22   23           Private   Void Backgroundworkerincludowork ( Object  Sender, doworkeventargs E)  24   {  25               //  Do not directly use the component Instance name (backgroundworker1) because there are many  26              //  Backgroundworker  27               //  Use it through the following Conversions  28 Backgroundworker worker = sender As  Backgroundworker;  29               //  The following content is equivalent to the content to be processed by the thread. Note: do not deal with controls in this event  30 Random r = New  Random ();  31              Int Numcount = 0  ;  32               While (Worker. cancellationpending = False  )  33   {  34                   Int Num = R. Next ( 10000  );  35                   If (Num % 5 = 0  )  36   {  37 Numcount ++ ;  38                       //  Raise BW. progresschanged () event  39 Worker. reportprogress ( 0  , Num );  40 Thread. Sleep ( 1000 );  41   }  42   }  43               //  Doworkeventargs. Result gets or sets the value indicating the asynchronous operation result.  44 E. Result = Numcount;  45   }  46   47   48           Private  Void Backgroundworker1_progresschanged ( Object  Sender, progresschangedeventargs E)  49   {  50               //  Object progresschangedeventargs. userstate to obtain the unique user status  51               Int Num = ( Int  ) E. userstate;  52 Richtextbox1.text + = num + " ,  "  ;  53   }  54   55           Private   Void Backgroundworkerappsrunworkercompleted ( Object  Sender, runworkercompletedeventargs E)  56   {  57               If (E. Error = Null )  58   {  59 Richtextbox1.text + = "  \ N operation stopped, a total  " + E. Result + "  Random number divisible by 5  "  ;  60   }  61               Else  62  {  63 Richtextbox1.text + = "  \ N errors occurred during operation:  " + E. error;  64   }  65              66   }  67   68           Private   Void Buttonstop_click (Object  Sender, eventargs E)  69   {  70               //  Request to cancel the pending operation  71   Backgroundworker1.cancelasync ();  72 Buttonstop. Enabled = False  ;  73 Buttonstart. Enabled = True  ; 74   }  75 }