namespace MyThread
{
    class FileServer
    {
        private String root;
        private Thread listenerThread;

private void worker(object state)
        {
             TcpClient client = state as TcpClient;
             try
             {

client.ReceiveTimeout = 2000;
                 Stream stream = client.GetStream();
                 System.IO.StreamReader sr = new StreamReader(stream);
                 String line = sr.ReadLine();
                 String[] array = line.Split(' ');
                 String path = array[1].Replace('/', '\\');
                 String filename = root + path;
                 if (File.Exists(filename))  // 如果下载文件存在，开始下载这个文件
                 {
                     FileStream fileStream = new FileStream(filename, FileMode.Open, FileAccess.Read,
                                                           FileShare.Read);
                     byte[] buffer = new byte[8192]; // 每次下载8K
                     int count = 0;
                     String responseHeader = "HTTP/1.1 200 OK\r\n" +
                                             "Content-Type:application/octet-stream\r\n" +
                                             "Content-Disposition:attachment;filename=" +
                                                   filename.Substring(filename.LastIndexOf("\\") + 1) + "\r\n\r\n";
                     byte[] header = ASCIIEncoding.ASCII.GetBytes(responseHeader);
                     stream.Write(header, 0, header.Length);
                     while ((count = fileStream.Read(buffer, 0, buffer.Count())) > 0)
                     {
                         stream.Write(buffer, 0, count);
                     }
                     Console.WriteLine(filename + "下载完成");
                 }
                 else  // 文件不存在，输出提示信息
                 {
                     String response = "HTTP/1.1 200 OK\r\nContent-Type:text/plain;charset=utf-8\r\n\r\n文件不存在";
                     byte[] buffer = ASCIIEncoding.UTF8.GetBytes(response);
                     stream.Write(buffer, 0, buffer.Length);
                 }

}
             catch (Exception e)
             {
                 Console.WriteLine(e.Message);
             }
             finally
             {
                 if (client != null)
                 {
                     client.Close();
                 }
             }
        }

private void listener()
        {
            TcpListener listener = new TcpListener(1234);
            listener.Start();  // 开始监听客户端请求
            TcpClient client = null;

while (true)
            {
                client = listener.AcceptTcpClient();
                client.ReceiveTimeout =2000;
                ThreadPool.QueueUserWorkItem(worker, client);  // 从线程池中获得一个线程来处理客户端请求
            }
        }
        public FileServer(String root)
        {
            this.root= root;        
        }
        public void start()
        {
            listenerThread = new Thread(listener);
            listenerThread.Start();  // 开始运行监听线程
        }
    }
}