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：
