ThreadPool的QueueUserWorkItem 方法 (WaitCallback)和QueueUserWorkItem 方法 (WaitCallback, Object)

注：要使用此方法都需要引入应用：using System.Threading;//引入应用

参数意义：将要执行的方法排入队列以便执行，WaitCallback，即表示将要执行的方法；Object，包含方法所用数据的对象。如果将方法成功排入队列，则为 true；否则为 false。

一、下面是ThreadPool.QueueUserWorkItem 方法 (WaitCallback)的示例代码：

 1 using System;

 2 using System.Collections.Generic;

 3 using System.Linq;

 4 using System.Text;

 5 using System.Threading;//引入应用

 6 

 7 namespace QueueUserWorkItem_WaitCallback_

 8 {

 9     class Program

10     {

11         static void Main(string[] args)

12         {

13             // Queue the task.

14             ThreadPool.QueueUserWorkItem(new WaitCallback(ThreadProc));

15 

16             Console.WriteLine("Main thread does some work, then sleeps.");

17             // If you comment out the Sleep, the main thread exits before

18             // the thread pool task runs.  The thread pool uses background

19             // threads, which do not keep the application running.  (This

20             // is a simple example of a race condition.)

21             Thread.Sleep(1000);

22 

23             Console.WriteLine("Main thread exits.");

24         }

25 

26         // This thread procedure performs the task.

27         static void ThreadProc(Object stateInfo)

28         {

29             // No state object was passed to QueueUserWorkItem, so 

30             // stateInfo is null.

31             Console.WriteLine("Hello from the thread pool.");

32         }

33     }

34 }

运行以上代码后：

二、下面是ThreadPool.QueueUserWorkItem 方法 (WaitCallback, Object)的示例代码：

 1 using System;

 2 using System.Collections.Generic;

 3 using System.Linq;

 4 using System.Text;

 5 using System.Threading;

 6 

 7 namespace QueueUserWorkItem__WaitCallback__Object_

 8 {

 9     //将方法排入队列以便执行，并指定包含该方法所用数据的对象。 此方法在有线程池线程变得可用时执行。

10     /*

11      * 

12      * public static bool QueueUserWorkItem(WaitCallback callBack,Object state)

13      * 

14      * 

15      * callBack  类型：System.Threading.WaitCallback

16      * WaitCallback ，它表示要执行的方法。

17      * 

18      * 

19      * state     类型：System.Object

20      * 包含方法所用数据的对象。

21      * 

22      * 

23      * 返回值    类型：System.Boolean

24      * 如果此方法成功排队，则为 true；如果无法将该工作项排队，则引发 NotSupportedException。

25      * 

26      * 

27      * 注：如果回调方法需要复杂数据，可以定义包含这些数据的类。

28      * 

29      */

30     class Program

31     {

32         static void Main(string[] args)

33         {

34             // Create an object containing the information needed for the task.

35             TaskInfo ti = new TaskInfo("This report displays the number {0}.", 42);

36 

37             // Queue the task and data.

38             ThreadPool.QueueUserWorkItem(new WaitCallback(ThreadProc), ti);

39 

40             Console.WriteLine("Main thread does some work, then sleeps.");

41 

42             // If you comment out the Sleep, the main thread exits before

43             // the ThreadPool task has a chance to run.  ThreadPool uses 

44             // background threads, which do not keep the application 

45             // running.  (This is a simple example of a race condition.)

46             Thread.Sleep(1000);

47 

48             Console.WriteLine("Main thread exits.");

49         }

50 

51         // The thread procedure performs the independent task, in this case

52         // formatting and printing a very simple report.

53         //

54         static void ThreadProc(Object stateInfo)

55         {

56             TaskInfo ti = (TaskInfo)stateInfo;

57             Console.WriteLine(ti.Boilerplate, ti.Value);

58         }

59     }

60 

61     // TaskInfo holds state information for a task that will be

62     // executed by a ThreadPool thread.

63     public class TaskInfo

64     {

65         // State information for the task.  These members

66         // can be implemented as read-only properties, read/write

67         // properties with validation, and so on, as required.

68         public string Boilerplate;

69         public int Value;

70 

71         // Public constructor provides an easy way to supply all

72         // the information needed for the task.

73         public TaskInfo(string text, int number)

74         {

75             Boilerplate = text;

76             Value = number;

77         }

78     }

79 }

运行以上代码后：