代码
1using System; 2using System.Threading; 3using System.ComponentModel; 4using System.Text; 5 6public class PiCalculator 7{ 8 public static BackgroundWorker calculationWorker = new BackgroundWorker(); 9 public static AutoResetEvent resetEvent = new AutoResetEvent(false); 10 11 public static void Main() 12 { 13 int digitCount; 14 15 Console.Write("Enter the number of digits to calculate:"); 16 17 if (int.TryParse(Console.ReadLine(), out digitCount)) 18 { 19 Console.WriteLine("ENTER to cancel"); 20 // C# 2.0 Syntax for registering delegates 21 calculationWorker.DoWork += CalculatePi; 22 // Register the ProgressChanged callback 23 calculationWorker.ProgressChanged += 24 UpdateDisplayWithMoreDigits; 25 calculationWorker.WorkerReportsProgress = true; 26 // Register a callback for when the 27 // calculation completes 28 calculationWorker.RunWorkerCompleted += 29 new RunWorkerCompletedEventHandler(Complete); 30 calculationWorker.WorkerSupportsCancellation = true; 31 32 // Begin calculating pi for up to digitCount digits 33 calculationWorker.RunWorkerAsync(digitCount); 34 35 Console.ReadLine(); 36 // If cancel is called after the calculation 37 // has completed it doesn't matter. 38 calculationWorker.CancelAsync(); 39 // Wait for Complete() to run. 40 resetEvent.WaitOne(); 41 } 42 else 43 { 44 Console.WriteLine( 45 "The value entered is an invalid integer."); 46 } 47 } 48 49 private static void CalculatePi(object sender, DoWorkEventArgs eventArgs) 50 { 51 int digits = (int)eventArgs.Argument; 52 53 StringBuilder pi = new StringBuilder("3.", digits + 2); 54 calculationWorker.ReportProgress(0, pi.ToString()); 55 56 // Calculate rest of pi, if required 57 if (digits > 0) 58 { 59 for (int i = 0; i < digits; i += 9) 60 { 61 62 63 // Calculate next i decimal places 64 int nextDigit = PiDigitCalculator.StartingAt( 65 i + 1); 66 int digitCount = Math.Min(digits - i, 9); 67 string ds = string.Format("{0:D9}", nextDigit); 68 pi.Append(ds.Substring(0, digitCount)); 69 70 // Show current progress 71 calculationWorker.ReportProgress( 72 0, ds.Substring(0, digitCount)); 73 74 // Check for cancellation 75 if (calculationWorker.CancellationPending) 76 { 77 // Need to set Cancel if you need to 78 // distinguish how a worker thread completed 79 // i.e., by checking 80 // RunWorkerCompletedEventArgs.Cancelled 81 eventArgs.Cancel = true; 82 break; 83 } 84 } 85 } 86 eventArgs.Result = pi.ToString(); 87 } 88 89 private static void UpdateDisplayWithMoreDigits(object sender, ProgressChangedEventArgs eventArgs) 90 { 91 string digits = (string)eventArgs.UserState; 92 93 Console.Write(digits); 94 95 } 96 97 static void Complete(object sender, RunWorkerCompletedEventArgs eventArgs) 98 { 99 Console.WriteLine();100 if (eventArgs.Cancelled)101 {102 Console.WriteLine("Cancelled");103 }104 else if (eventArgs.Error != null)105 {106 // IMPORTANT: check error to retrieve any exceptions. 107 Console.WriteLine(108 "ERROR: {0}", eventArgs.Error.Message);109 }110 else111 {112 Console.WriteLine("Finished");113 }114 resetEvent.Set();115116 }117}118119public class PiDigitCalculator120{121 // 122 public static int StartingAt(int i)123 {124 Thread.Sleep(1000);125 return i;126 }127}
转载于:https://www.cnblogs.com/nanshouyong326/archive/2007/05/10/741807.html
相关资源：数据结构—成绩单生成器
