C#開啟線程的幾種方式

方式一：通過委托發起線程（BeginInvoke）：

Func<int, int> a = Test;
IAsyncResult ar = a.BeginInvoke(20, OnCallBack, a);//倒數第二個參數是一個委托類型的參數，表示回調函數，當線程結束時會調用這個委托指向的方法；倒數第一個參數用來給回調函數傳遞數據；通過ar獲取數據a

方式二：通過Thread發起線程，thread創建的線程都是前台線程，線程池創建的線程都是后台線程

1. thread參數為靜態方法

        static void Downloadfile()
        {
            Console.WriteLine("開始下載" + Thread.CurrentThread.ManagedThreadId);
            Thread.Sleep(2000);
            Console.WriteLine("下載完成");
        }

        static void Main(string[] args)
        {
            Thread t = new Thread(Downloadfile);
            t.Start();
            Console.WriteLine("main");
            Console.ReadKey();
        }

2. lamda表達式

Thread t = new Thread(() =>
    {
        Console.WriteLine("開始下載" + Thread.CurrentThread.ManagedThreadId);
        Thread.Sleep(2000);
        Console.WriteLine("下載完成");
    });
t.Start();    

3. Thread參數為普通方法

    class Program
    {
        static void Downloadfile(object filename)
        {
            Console.WriteLine("開始下載" + filename+ Thread.CurrentThread.ManagedThreadId);
            Thread.Sleep(2000);
            Console.WriteLine("下載完成"+filename);
        }

        static void Main(string[] args)
        {
            //Thread t = new Thread(() =>
            //{

            //    Console.WriteLine("開始下載" + Thread.CurrentThread.ManagedThreadId);
            //    Thread.Sleep(2000);
            //    Console.WriteLine("下載完成");
            //});
            //Thread t = new Thread(Downloadfile);
            MyThread my = new MyThread("xxx.bt", "http://www.xxx.bbs");
            Thread t = new Thread(my.DownFile);
            t.Start();
            Console.WriteLine("main");
            Console.ReadKey();
        }
    }

    class MyThread
    {
        private string filename;
        private string filepath;
        public MyThread(string fileName, string filePath)
        {
            this.filename = fileName;
            this.filepath = filePath;
        }

        public void DownFile()
        {
            Console.WriteLine("開始下載" + filepath + filename);
            Thread.Sleep(2000);
            Console.WriteLine("下載完成");
        }

    }
}

方式三：線程池：適合用於小任務線程,

WaitCallback:將方法排入隊列以便執行，WaitCallback，表示要執行的方法。如果將方法成功排入隊列，則為 true；否則為 false。

    class Program
    {
        static void ThreadMethod(object state)
        {
            Console.WriteLine("線程開始"+Thread.CurrentThread.ManagedThreadId);
            Thread.Sleep(2000);
            Console.WriteLine("線程結束");
        }
        static void Main(string[] args)
        {
            ThreadPool.QueueUserWorkItem(ThreadMethod);
            ThreadPool.QueueUserWorkItem(ThreadMethod);
            ThreadPool.QueueUserWorkItem(ThreadMethod);
            ThreadPool.QueueUserWorkItem(ThreadMethod);
            ThreadPool.QueueUserWorkItem(ThreadMethod);
            Console.ReadKey();
        }
    }

方式四：任務線程

1. 通過Task創建

class Program
    {
        static void ThreadMethod()
        {
            Console.WriteLine("任務開始" + Thread.CurrentThread.ManagedThreadId);
            Thread.Sleep(2000);
            Console.WriteLine("任務結束");
        }

        static void Main(string[] args)
        {
            Task t = new Task(ThreadMethod);
            t.Start();
            Console.WriteLine("main");
            Console.ReadKey();
        }
    }

2. 通過TaskFactory創建

TaskFactory tf = new TaskFactory();
tf.StartNew(ThreadMethod);   

　tf.StartNew(ThreadMethod);
　tf.StartNew(ThreadMethod)；