C#線程系列講座(3)：線程池和文件下載服務器(2)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Net.Sockets;
using System.IO;
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))  // 如果下載文件存在，開始下載這個文件
                 {
                     FileStream fileStream = new FileStream(filename, FileMode.Open, FileAccess.Read, 
                                                           FileShare.Read);
                     byte[] buffer = new byte[8192]; // 每次下載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 + "下載完成");
                 }
                 else  // 文件不存在，輸出提示信息
                 {
                     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();  // 開始監聽客戶端請求
            TcpClient clIEnt = null;
            while (true)
            {
                client = listener.AcceptTcpClIEnt();
                clIEnt.ReceiveTimeout =2000;
                ThreadPool.QueueUserWorkItem(worker, clIEnt);  // 從線程池中獲得一個線程來處理客戶端請求
            }
        }
        public FileServer(String root)
        {
            this.root= root;         
        }
        public void start()
        {
            listenerThread = new Thread(listener);
            listenerThread.Start();  // 開始運行監聽線程
        }
    }
}