Question

我正在阅读我要发布的那个例子，我不明白的是：他们说，如果我想与GUI进行交互，则必须由UI线程完成。换句话说：使用Controll类的.Invoke方法。在示例中，我不明白为什么我们在output.Invoke...方法中使用GenerateRandomCharacters来改变输出，但在Toggle()中输出也在改变（其颜色））没有.Invoke？是不是一样？

public class RandomLetters
{
    private static Random generator = new Random(); // for random letters
    private bool suspended = false; // true if thread is suspended
    private Label output; // Label to display output
    private string threadName; // name of the current thread

   // RandomLetters constructor
   public RandomLetters( Label label )
   {
      output = label;
   } // end RandomLetters constructor

   // delegate that allows method DisplayCharacter to be called
   // in the thread that creates and maintains the GUI
   private delegate void DisplayDelegate( char displayChar );

   // method DisplayCharacter sets the Label's Text property
   private void DisplayCharacter( char displayChar )
   {
   // output character in Label
      output.Text = threadName + ": " + displayChar;
   } // end method DisplayCharacter

   // place random characters in GUI
   public void GenerateRandomCharacters()
   {
   // get name of executing thread
      threadName = Thread.CurrentThread.Name;

      while ( true ) // infinite loop; will be terminated from outside
      {
      // sleep for up to 1 second
         Thread.Sleep( generator.Next( 1001 ) );

         lock ( this ) // obtain lock
         {
           while ( suspended ) // loop until not suspended
           {
             Monitor.Wait( this ); // suspend thread execution
           } // end while
         } // end lock
         // select random uppercase letter
         char displayChar = ( char ) ( generator.Next( 26 ) + 65 );

         // display character on corresponding Label
         output.Invoke( new DisplayDelegate( DisplayCharacter ),
         new object[] { displayChar } );
      } // end while
    } // end method GenerateRandomCharacters

    // change the suspended/running state
    public void Toggle()
    {
       suspended = !suspended; // toggle bool controlling state

       // change label color on suspend/resume
       output.BackColor = suspended ? Color.Red : Color.LightGreen;

       lock ( this ) // obtain lock
       {
          if ( !suspended ) // if thread resumed
          Monitor.Pulse( this );
       } // end lock
     } // end method Toggle
  } // end class RandsomLetters

编辑：这是实际的电话：

public partial class GUIThreadsForm : Form
{
    public GUIThreadsForm()
    {
        InitializeComponent();
    } // end constructor

    private RandomLetters letter1; // first RandomLetters object
    private RandomLetters letter2; // second RandomLetters object
    private RandomLetters letter3; // third RandomLetters object

    private void GUIThreadsForm_Load( object sender, EventArgs e )
    {
        // create first thread
        letter1 = new RandomLetters( thread1Label );
        Thread firstThread = new Thread(
            new ThreadStart( letter1.GenerateRandomCharacters ) );
        firstThread.Name = "Thread 1";
        firstThread.Start();

        continues...

这是调用Toggle（）方法的方式：

private void threadCheckBox_CheckedChanged( object sender, EventArgs e )
{
    if ( sender == thread1CheckBox )
        letter1.Toggle();
    else if ( sender == thread2CheckBox )
        letter2.Toggle();
    else if ( sender == thread3CheckBox )
        letter3.Toggle();
} // end method threadCheckBox_CheckedChanged

在CheckedChanged事件中激活复选框控件后，它进入Toggle（）方法

Answer 1

无论是什么调用这个类的方法只是从非UI线程调用GenerateRandomCharacters，而Toggle只是从UI线程调用，因此只有GenerateRandomCharacters需要显式封送到UI线程。

您需要了解如何调用这些方法来验证。

关于在c＃中使用GUI进行多线程处理

1 个答案: