C# 线程的挂起与恢复

        private void Form1_Load(object sender,EventArgs e)
        {
            Thread fd_thr = new Thread(this.FileDownload);
            fd_thr.Start();
            fd_thr.Suspend(); // 挂起线程,过时
            fd_thr.Resume();  // 恢复线程,过时
        }

        private void FileDownload()
        {
            byte[] buffer = null;
            using (WebClient client = new WebClient())
                buffer = client.DownloadData("http://www.baidu.com");
            Console.WriteLine(Encoding.UTF8.GetString(buffer));
        }

下面的代码，貌似没有问题，但你可能会在输出面板会出现一句错误“引发的异常:

        private AutoResetEvent fd_thr_supend = new AutoResetEvent(false);

        private void Form1_Load(object sender,EventArgs e)
        {
            Thread fd_thr = new Thread(this.FileDownload);
            fd_thr.Start();
            this.fd_thr_supend.Reset(); // 挂起线程
            this.fd_thr_supend.Set(); // 恢复线程
        }

        private void FileDownload()
        {
            byte[] buffer = null;
            using (WebClient client = new WebClient())
                buffer = client.DownloadData("http://www.baidu.com");
            this.fd_thr_supend.WaitOne(); // 阻塞，等待信号
            Console.WriteLine(Encoding.UTF8.GetString(buffer));
        }

上面则配合AutoResetEvent方式配合进行线程的挂起或恢复，这样做有利代码的

        [DllImport("kernel32.dll",SetLastError = true)]
        private static extern int GetCurrentThreadId();

        [DllImport("kernel32.dll",SetLastError = true)]
        private static extern int SuspendThread(IntPtr hThread);

        [DllImport("kernel32.dll",SetLastError = true)]
        public static extern uint ResumeThread(IntPtr hThread);

        public int hCurrenthThreadId;

        [DllImport("kernel32.dll",SetLastError = true)]
        public static extern IntPtr OpenThread(int dwDesiredAccess,bool bInheritHandle,uint dwThreadId);

        public const int THREADACCESS_SUSPEND_RESUME = 0x0002;

        private void Form1_Load(object sender,EventArgs e)
        {
            Thread fd_thr = new Thread(this.FileDownload);
            fd_thr.Start();
            while (this.hCurrenthThreadId == 0); // 等待线程被启动
            IntPtr hCurrenthThread = OpenThread(THREADACCESS_SUSPEND_RESUME,false,(uint)this.hCurrenthThreadId);
            // 挂起线程
            SuspendThread(hCurrenthThread);
            // 恢复线程
            ResumeThread(hCurrenthThread); 
        }

        private void FileDownload()
        {
            this.hCurrenthThreadId = GetCurrentThreadId();
            byte[] buffer = null;
            using (WebClient client = new WebClient())
                buffer = client.DownloadData("http://www.baidu.com");
            Console.WriteLine(Encoding.UTF8.GetString(buffer));
        }

上面的方法也不安全，因为上面的做法其实与Thread.Resume()与Thread.Suspend()两个函数的