C# 线程更新ui

本部分包含两个示例。 第一个示例演示如何创建执行静态方法的线程。 第二个示例演示如何创建执行实例方法的线程。

这些示例在 UI 线程上的 TextBlock 中显示它们的输出。 为了从回调线程访问 TextBlock，这些示例使用 Dispatcher 属性来获取 TextBlock 的 Dispatcher 对象，然后使用 Dispatcher.BeginInvoke 方法进行跨线程调用。

有关创建线程的更多示例，请参见启动时创建线程并传递数据。 有关使用等待句柄协调线程操作的示例，请参见 EventWaitHandle。 有关使用临界区（在 C# 中为 lock，在 Visual Basic 中为 SyncLock）协调线程操作的示例，请参见Monitor。 有关如何使用线程池线程的示例，请参见 BackgroundWorker、ThreadPool 和 Timer。

示例 1

下面的示例演示如何创建执行静态方法的线程。

说明：
若要运行此示例，请参见生成使用 Demo 方法和 TextBlock 控件的示例。

C#

VB

 

using System;

using System.Threading;



public class Example

{

   private static System.Windows.Controls.TextBlock outputBlock;



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

   {

      Example.outputBlock = outputBlock;



      // To start a thread using a static thread procedure, use the

      // class name and method name when you create the ThreadStart

      // delegate. C# expands the method name to the appropriate 

      // delegate creation syntax:

      //    New ThreadStart(Example.DoWork)

      //

      Thread newThread = new Thread(Example.DoWork);

      newThread.Start();

   }



   // Simulate work. To communicate with objects on the UI thread, get the 

   // Dispatcher for one of the UI objects. Use the Dispatcher object's 

   // BeginInvoke method to queue a delegate that will run on the UI thread,

   // and therefore can safely access UI elements like the TextBlock.

   private static void DoWork()

   {

      outputBlock.Dispatcher.BeginInvoke(delegate () { 

         outputBlock.Text += "Hello from a static thread procedure.\n"; 

      });

   }

}



/* This code example produces the following output:



Hello from a static thread procedure.

 */

示例 2

下面的示例演示如何创建执行实例方法的线程。

说明：
若要运行此示例，请参见生成使用 Demo 方法和 TextBlock 控件的示例。

C#

VB

 

using System;

using System.Threading;



public class Example

{

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

   {

      // To start a thread using an instance method for the thread 

      // procedure, use the instance variable and method name when 

      // you create the ThreadStart delegate. C# expands the object

      // reference and method name to the appropriate delegate 

      // creation syntax:

      //    New ThreadStart(AddressOf w.DoMoreWork)

      //

      Work w = new Work();

      w.Data = 42;

      w.Output = outputBlock;



      Thread newThread = new Thread(w.DoMoreWork);

      newThread.Start();

   }

}



public class Work

{

   public int Data;

   public System.Windows.Controls.TextBlock Output;



   // Simulate work. To communicate with objects on the UI thread, get the 

   // Dispatcher for one of the UI objects. Use the Dispatcher object's 

   // BeginInvoke method to queue a delegate that will run on the UI thread,

   // and therefore can safely access UI elements like the TextBlock.

   public void DoMoreWork()

   {

      Output.Dispatcher.BeginInvoke(delegate () {

         Output.Text += String.Format("Instance thread procedure. Data={0}\n", Data);

      });

   }

}



// This code example produces the following output:

//

//Instance thread procedure. Data=42