c#面試題及答案整理（三）

阿新 • • 發佈：2022-03-04

1.C#多執行緒

a.建立執行緒

執行緒是通過擴充套件 Thread 類建立的。擴充套件的 Thread 類呼叫Start()方法來開始子執行緒的執行。

下面的程式演示了這個概念：

using System;
using System.Threading;

namespace MultithreadingApplication
{
    class ThreadCreationProgram
    {
        public static void CallToChildThread()
        {
            Console.WriteLine("Child thread starts 
");
        }
        
        static void Main(string[] args)
        {
            ThreadStart childref = new ThreadStart(CallToChildThread);
            Console.WriteLine("In Main: Creating the Child thread");
            Thread childThread = new Thread(childref);
            childThread.Start();
            Console.ReadKey();
        }
    }
}

B.管理執行緒

Thread 類提供了各種管理執行緒的方法。

下面的例項演示了sleep()方法的使用，用於在一個特定的時間暫停執行緒。

using System;
using System.Threading;

namespace MultithreadingApplication
{
    class ThreadCreationProgram
    {
        public static void CallToChildThread()
        {
            Console.WriteLine("Child thread starts");
             
// 執行緒暫停 5000 毫秒
            int sleepfor = 5000; 
            Console.WriteLine("Child Thread Paused for {0} seconds", 
                              sleepfor / 1000);
            Thread.Sleep(sleepfor);
            Console.WriteLine("Child thread resumes");
        }
        
        static void Main(string[] args)
        {
            ThreadStart childref = new ThreadStart(CallToChildThread);
            Console.WriteLine("In Main: Creating the Child thread");
            Thread childThread = new Thread(childref);
            childThread.Start();
            Console.ReadKey();
        }
    }
}

c.銷燬執行緒

Abort()方法用於銷燬執行緒。

通過丟擲threadabortexception在執行時中止執行緒。這個異常不能被捕獲，如果有finally塊，控制會被送至finally塊。

下面的程式說明了這點：

using System;
using System.Threading;

namespace MultithreadingApplication
{
    class ThreadCreationProgram
    {
        public static void CallToChildThread()
        {
            try
            {

                Console.WriteLine("Child thread starts");
                // 計數到 10
                for (int counter = 0; counter <= 10; counter++)
                {
                    Thread.Sleep(500);
                    Console.WriteLine(counter);
                }
                Console.WriteLine("Child Thread Completed");
            }
            catch (ThreadAbortException e)
            {
                Console.WriteLine("Thread Abort Exception");
            }
            finally
            {
                Console.WriteLine("Couldn't catch the Thread Exception");
            }
        }                  static void Main(string[] args)
        {
            ThreadStart childref = new ThreadStart(CallToChildThread);
            Console.WriteLine("In Main: Creating the Child thread");
            Thread childThread = new Thread(childref);
            childThread.Start();
            // 停止主執行緒一段時間
            Thread.Sleep(2000);             // 現在中止子執行緒
            Console.WriteLine("In Main: Aborting the Child thread");
            childThread.Abort();
            Console.ReadKey();
        }
    }
}