多線程學習（一）

線程的基本操作
線程的基本操作包括：創建線程、暫停線程、線程等待、終止線程。

 1 /*-----------------------------------------------------------------------
 2                         written by helio, 2019
 3                             ThreadSample1
 4 -----------------------------------------------------------------------*/
 5 using System;
 6 using System.Threading;
 7 
 8 namespace ThreadSample
 9 {
10     class Program
11     {
12         static void FirstPrintNumbsers()
13         {
14             Console.WriteLine("{0} starting..", Thread.CurrentThread.Name);
15             for (int i = 1; i <= 10; i++)
16             {
17                 Console.WriteLine(i);
18                 Thread.Sleep(TimeSpan.FromMilliseconds(100));
19             }
20         }
21 
22         static void SecondPrintNumbers()
23         {
24             Console.WriteLine("{0} starting...", Thread.CurrentThread.Name);
25             for (int i = 1; i <= 10; i++)
26             {
27                 Console.WriteLine(i);
28                 Thread.Sleep(TimeSpan.FromMilliseconds(100));
29             }
30         }
31         static void Main(string[] args)
32         {
33             Thread t1 = new Thread(FirstPrintNumbsers);
34             Thread t2 = new Thread(SecondPrintNumbers);
35             t1.Name = "Thread1";
36             t2.Name = "Thread2";
37             t1.Start();
38             t2.Start();
39             t1.Join();                    
40             t2.Join();
41 
42             Thread.CurrentThread.Name = "MainThread";
43             FirstPrintNumbsers();
44             Console.ReadKey();
45         }
46     }
47 }

　　工作原理
在Main方法外定義了方法FristPrintNumbers、SecondPrintNumbers，該方法會被主程式和向創建的兩個線程Thread1、Thread2使用。創建完成線程後，使用Start方法啟動線程，使用Join方法值線程執行完成後繼續執行主線程或者該線程下麵的線程。

前臺線程和後臺線程

 1 ```
 2 /*-----------------------------------------------------------------------
 3                         written by helio, 2019
 4                             ThreadSample2
 5 -----------------------------------------------------------------------*/
 6 using System;
 7 using System.Threading;
 8 
 9 namespace ThreadSample
10 {
11     class Program
12     {
13         static void Main(string[] args)
14         {
15             var sampleForeground = new ThreadSample(10);
16             var sampleBackground = new ThreadSample(20);
17 
18             var ThreadOne = new Thread(sampleForeground.CountNumbers);
19             ThreadOne.Name = "ForegourndThread";
20             var ThreadTwo = new Thread(sampleBackground.CountNumbers);
21             ThreadTwo.Name = "BackgroundThread";
22             ThreadTwo.IsBackground = true;
23 
24             ThreadOne.Start();
25             ThreadTwo.Start();
26         }
27 
28         class ThreadSample
29         {
30             private readonly int m_iteration;
31 
32             public ThreadSample(int iteration)
33             {
34                 m_iteration = iteration;
35             }
36 
37             public void CountNumbers()
38             {
39                 for (int i = 0; i < m_iteration; i++)
40                 {
41                     Thread.Sleep(TimeSpan.FromSeconds(0.5));
42                     Console.WriteLine("{0} prints {1}",
43                         Thread.CurrentThread.Name, i);
44                 }
45             }
46         }
47     }
48 }
49 ```

　　工作原理

　　當主程式啟動時定義了兩個不同的線程。預設情況下，顯示創建的線程是前臺線程。通過手動設置ThradTow對象的IsBackkgournd來創建一個後臺線程。<br/>
　　當一個程式中的前臺線程完成工作後，程式就會關閉，即使還有未完成工作的後臺線程。所以在上述程式中，前臺線程Thread1完成工作後程式就會別關閉。

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