WPF中的多进程(Threading)处理实例(一)

原文:WPF中的多进程(Threading)处理实例(一)

说明：希望通过揣摩这些案例，能进一步了解进程的工作原理。

1.方法一描述的是在同一窗口中，在计算素数的同时而不影响Canvas的工作。

方法1

         #region Long-Running Calculation in UI Thread

         public delegate void NextPrimeDelegate();
         private long num = ;
         private bool continueCalculating = false;
         private bool fNotAPrime = false;

         private void btnPrimeNumber_Click(object sender, RoutedEventArgs e)
         {
             if (continueCalculating)
             {
                 continueCalculating = false;
                 btnPrimeNumber.Content = "Resume";
             }
             else
             {
                 continueCalculating = true;
                 btnPrimeNumber.Content = "Stop";

                 //获取与此 System.Windows.Threading.DispatcherObject 关联的 System.Windows.Threading.Dispatcher

                 //public DispatcherOperation BeginInvoke(DispatcherPriority priority, Delegate method);
                 //按指定的优先级在与 System.Windows.Threading.Dispatcher 关联的线程上异步执行指定的委托。
                 btnPrimeNumber.Dispatcher.BeginInvoke(DispatcherPriority.Normal, new NextPrimeDelegate(CheckNextNumber));

             }
         }

         public void CheckNextNumber()
         {
             // Reset flag.
             fNotAPrime = false;

             for (long i = ; i <= Math.Sqrt(num); i++)
             {
                 if (num % i == )
                 {
                     // Set not-a-prime flag to true.
                     fNotAPrime = true;
                     break;
                 }
             }

             // If a prime number.
             if (!fNotAPrime)
             {
                 tbPrime.Text = num.ToString();
             }

             num += ;

             if (continueCalculating)
             {
                 //3.In the CheckNextNumber function, because the first parameter
                 //passed into BeginInvoke is DispatcherPriority.SystemIdle(在系统空闲时处理操作。),
                 //all of the CheckNextNumber workitem will not break the UI operation.

                 btnPrimeNumber.Dispatcher.BeginInvoke(
                     System.Windows.Threading.DispatcherPriority.SystemIdle,
                     new NextPrimeDelegate(this.CheckNextNumber));
             }
         }

         #endregion

方法2

   #region Blocking Operation in Worker Thread

         private delegate void NoArgDelegate();
         private delegate void OneArgDelegate(Int32[] arg);

         //1.When the Retrieve Data from Server button is clicked, the click handle retrieveData function is called.
         private void btnRetrieveData_Click(object sender, RoutedEventArgs e)
         {
             this.btnRetrieveData.IsEnabled = false;
             this.btnRetrieveData.Content = "Contacting Server";

             NoArgDelegate fetcher = new NoArgDelegate(this.RetrieveDataFromServer);

             //2.Then our codes use delegate.BeginInvoke to start a thread from the thread pool.
             //This thread is used to perform the long operation of retrieving data.
             fetcher.BeginInvoke(null, null);
         }

         /// <summary>
         /// Retrieve data in a worker thread(辅助线程).
         /// </summary>
         private void RetrieveDataFromServer()
         {
             //3.We use Thread.Sleep(5000) to simulate(模拟) a 5 seconds delay here.
             // Simulate the delay from network access.
             Thread.Sleep();

             //4.The codes generate 4 random numbers as data and update them to the UI by calling the Dispatcher.BeginInvoke().

             // Generate random data to be displayed.
             Random rand = new Random();
             Int32[] data = {
                                rand.Next(), rand.Next(),
                                rand.Next(), rand.Next()
                            };

             // Schedule the update function in the UI thread.
             this.Dispatcher.BeginInvoke(System.Windows.Threading.DispatcherPriority.Normal,
                 new OneArgDelegate(UpdateUserInterface),  data);

         }

         /// <summary>
         /// Update the UI about the new data. The function runs in the UI thread.
         /// </summary>
         /// <param name="data"></param>
         private void UpdateUserInterface(Int32[] data)
         {
             this.btnRetrieveData.IsEnabled = true;
             this.btnRetrieveData.Content = "Retrieve Data from Server";
             this.tbData1.Text = data[].ToString();
             this.tbData2.Text = data[].ToString();
             this.tbData3.Text = data[].ToString();
             this.tbData4.Text = data[].ToString();
         }

         #endregion