Timer 类 计时器

代码

   
     

    
      
    
       1 
    
      /*
    
      

    
       2 
    
       * class Example

    
       3 
    
      {

    
       4 
    
       public static void Demo(System.Windows.Controls.TextBlock outputBlock)

    
       5 
    
       {

    
       6 
    
       outputBlock.Text += "This message is never seen by users.\n";

    
       7 
    
       }

    
       8 
    
      }

    
       9 
    
       
    
      */
    
      

    
       10 
    
       
    
      using
    
       System;

    
       11 
    
       
    
      using
    
       System.Threading;

    
       12 
    
      

    
       13 
    
       
    
      //
    
       The following Imports are not required for the timer. They merely simplify 

    
       14 
    
      
    
      //
    
       the code.
    
      

    
       15 
    
      
    
      using
    
       System.Windows.Controls;

    
       16 
    
      
    
      using
    
       System.Windows.Input;

    
       17 
    
      

    
       18 
    
      
    
      //
    
       The Example class holds a reference to the timer, and contains the 

    
       19 
    
      
    
      //
    
       event handler for the MouseLeftButtonUp events that control the demo.

    
       20 
    
      
    
      //

    
       21 
    
      
    
      public
    
       
    
      class
    
       Example

    
       22 
    
      {

    
       23 
    
       
    
      //
    
       The static Demo method sets the starting message and creates an 

    
       24 
    
       
    
      //
    
       instance of Example, which hooks up the handler for the MouseLeftButtonUp

    
       25 
    
       
    
      //
    
       event.
    
      

    
       26 
    
      
    
       
    
      public
    
       
    
      static
    
       
    
      void
    
       Demo(TextBlock outputBlock)

    
       27 
    
       {

    
       28 
    
       outputBlock.Text 
    
      +=
    
       
    
      "
    
      Click to create the timer.\n
    
      "
    
      ;

    
       29 
    
       Example dummy 
    
      =
    
       
    
      new
    
       Example(outputBlock);

    
       30 
    
       }

    
       31 
    
      

    
       32 
    
      

    
       33 
    
       
    
      //
    
       Instance data for the demo.
    
      

    
       34 
    
      
    
       
    
      private
    
       
    
      int
    
       phase 
    
      =
    
       
    
      0
    
      ;

    
       35 
    
       
    
      private
    
       Timer t;

    
       36 
    
      

    
       37 
    
       
    
      public
    
       Example(TextBlock outputBlock)

    
       38 
    
       {

    
       39 
    
       
    
      //
    
       Hook up the mouse event when a new Example object is created. Note

    
       40 
    
       
    
      //
    
       that this keeps garbage collection from reclaiming the Example 

    
       41 
    
       
    
      //
    
       object.
    
      

    
       42 
    
      
    
       outputBlock.MouseLeftButtonUp 
    
      +=
    
       
    
      new
    
       MouseButtonEventHandler(
    
      this
    
      .MouseUp);

    
       43 
    
       }

    
       44 
    
      

    
       45 
    
       
    
      private
    
       
    
      void
    
       MouseUp(
    
      object
    
       sender, MouseButtonEventArgs e)

    
       46 
    
       {

    
       47 
    
       TextBlock outputBlock 
    
      =
    
       (TextBlock) sender;

    
       48 
    
      

    
       49 
    
       
    
      if
    
       (phase
    
      ==
    
      0
    
      )

    
       50 
    
       {

    
       51 
    
       
    
      //
    
       On the first click, create the timer.
    
      

    
       52 
    
      
    
       outputBlock.Text 
    
      +=
    
       
    
      "
    
      \nCreating the timer at 
    
      "
    
       
    
      +
    
       

    
       53 
    
       DateTime.Now.ToString(
    
      "
    
      h:mm:ss.fff
    
      "
    
      ) 
    
      +
    
       

    
       54 
    
       
    
      "
    
      , to start in 1 second with a half-second interval.\n
    
      "
    
       
    
      +
    
      

    
       55 
    
       
    
      "
    
      Click to change the interval from 1/2 second to 1 second.\n\n
    
      "
    
      ;

    
       56 
    
      

    
       57 
    
       
    
      //
    
       Create a timer that invokes the callback method after one second 

    
       58 
    
       
    
      //
    
       (1000 milliseconds) and every 1/2 second thereafter. The TextBlock

    
       59 
    
       
    
      //
    
       that is used for output is passed as the state object. C# infers the 

    
       60 
    
       
    
      //
    
       delegate type, as if you had typed the following:

    
       61 
    
       
    
      //
    
       new TimerCallback(MyTimerCallback)

    
       62 
    
       
    
      //
    
       
    
      

    
       63 
    
      
    
       t 
    
      =
    
       
    
      new
    
       Timer(MyTimerCallback, outputBlock, 
    
      1000
    
      , 
    
      500
    
      );

    
       64 
    
       

    
       65 
    
       }

    
       66 
    
       
    
      else
    
       
    
      if
    
       (phase
    
      ==
    
      1
    
      )

    
       67 
    
       {

    
       68 
    
       outputBlock.Text 
    
      +=
    
       
    
      "
    
      \nChanging the interval to one second.\n
    
      "
    
       
    
      +
    
      

    
       69 
    
       
    
      "
    
      Click to destroy the timer.\n\n
    
      "
    
      ;

    
       70 
    
       t.Change(
    
      0
    
      , 
    
      1000
    
      );

    
       71 
    
       }

    
       72 
    
       
    
      else
    
      

    
       73 
    
       {

    
       74 
    
       
    
      //
    
       On the last click, destroy the timer and shut down the demo.
    
      

    
       75 
    
      
    
       outputBlock.Text 
    
      +=
    
       
    
      "
    
      \nDestroying the timer.\n
    
      "
    
       
    
      +
    
       

    
       76 
    
       
    
      "
    
      Refresh the page to run the demo again.
    
      "
    
      ;

    
       77 
    
       outputBlock.MouseLeftButtonUp 
    
      -=
    
       
    
      new
    
       MouseButtonEventHandler(
    
      this
    
      .MouseUp);

    
       78 
    
      

    
       79 
    
       t.Dispose();

    
       80 
    
       }

    
       81 
    
      

    
       82 
    
       phase 
    
      +=
    
       
    
      1
    
      ;

    
       83 
    
       }

    
       84 
    
      

    
       85 
    
      

    
       86 
    
       
    
      //
    
       The static callback method is invoked on a ThreadPool thread by the Timer. 

    
       87 
    
       
    
      //
    
       The state object is passed to the callback method on each invocation. In this

    
       88 
    
       
    
      //
    
       example, the state object is the TextBlock that displays output. In order to

    
       89 
    
       
    
      //
    
       update the TextBlock object, which is on the UI thread, you must make the 

    
       90 
    
       
    
      //
    
       cross-thread call by using the Dispatcher object that is associated with the 

    
       91 
    
       
    
      //
    
       TextBlock.
    
      

    
       92 
    
      
    
       
    
      private
    
       
    
      static
    
       
    
      void
    
       MyTimerCallback(
    
      object
    
       state)

    
       93 
    
       {

    
       94 
    
       TextBlock outputBlock 
    
      =
    
       (TextBlock) state;

    
       95 
    
       
    
      string
    
       msg 
    
      =
    
       DateTime.Now.ToString(
    
      "
    
      h:mm:ss.fff
    
      "
    
      ) 
    
      +
    
       
    
      "
    
       MyTimerCallback was called.\n
    
      "
    
      ;

    
       96 
    
      

    
       97 
    
       outputBlock.Dispatcher.BeginInvoke(
    
      delegate
    
       () { outputBlock.Text 
    
      +=
    
       msg; });

    
       98 
    
       }

    
       99 
    
      }

    
      100 
    
      

    
      101 
    
      
    
      /*
    
       This example produces output similar to the following:

    
      102 
    
      

    
      103 
    
      Click to create the timer.

    
      104 
    
      

    
      105 
    
      Creating the timer at 3:40:17.712, to start in 1 second with a half-second interval.

    
      106 
    
      Click to change the interval from 1/2 second to 1 second.

    
      107 
    
      

    
      108 
    
      3:40:18.820 MyTimerCallback was called.

    
      109 
    
      3:40:19.335 MyTimerCallback was called.

    
      110 
    
      3:40:19.849 MyTimerCallback was called.

    
      111 
    
      

    
      112 
    
      Changing the interval to one second.

    
      113 
    
      Click to destroy the timer.

    
      114 
    
      

    
      115 
    
      3:40:20.317 MyTimerCallback was called.

    
      116 
    
      3:40:21.331 MyTimerCallback was called.

    
      117 
    
      

    
      118 
    
      Destroying the timer.

    
      119 
    
      Refresh the page to run the demo again.

    
      120 
    
       
    
      */
   
     

 

  
    

   
     
   
      
   
     <
   
     Grid 
   
     x:Name
   
     ="LayoutRoot"
   
      Background
   
     ="White"
   
     >
   
     
 
   
     <
   
     TextBlock 
   
     x:Name 
   
     = "outputBlock"
   
      FontSize
   
     ="12"
   
      TextWrapping
   
     ="Wrap"
   
      
   
     />
   
     
 
 
   
     </
   
     Grid
   
     >
  
    

 

  
    

   
     
   
      
   
     public
   
      Page()
 {
 InitializeComponent();
 Example.Demo(outputBlock);

 }