httpHandlers文件下載

1:編寫一個實現IHttpHandler的類。 

 

 public class DownloadFileProcesser : IHttpHandler
    ...{
        private DownLoadData logdata = new DownLoadData();
        public DownloadFileProcesser()
        ...{

        }

        public void ProcessRequest(HttpContext context)
        ...{
                       string fileName = context.Request.Url.OriginalString;   //獲取請求的url
               string ORIGINALURL = fileName;  //完整的請求路徑
       int index = fileName.LastIndexOf("/");    //取最後一個/的未知
            fileName = fileName.Substring(index + 1);                 string filepath = fileName;
            int iBegin = fileName.LastIndexOf("_");  //取"_"之前和"."後面的，組成aaa.dd
            int iEnd = fileName.LastIndexOf(".");

            string localPath = System.Configuration.ConfigurationManager.AppSettings["downLoadPath"];  //下載文件的存放路徑
            if (iBegin >= 0)
            ...{
                filepath = fileName.Substring(0, iBegin) + fileName.Substring(iEnd);
                filepath = context.Server.MapPath(localPath + filepath);
            }
            else
            ...{
                //  filepath = Path.Combine(localPath, fileName);
                filepath = context.Server.MapPath(localPath + fileName);
            }
            //  downLoadHandle aa = new downLoadHandle(outputBinary);
            if (File.Exists(filepath))  //文件是否存在。不存在的話按照真實文件名下載
            ...{
                outputBinary(fileName, filepath, context);
                sendState = 1;
            }
            else
            ...{
                context.Response.Status = "404 Not Found ";
                sendState = 0;
            }
            logdata.SENDSTATE = sendState;
           int indexLfn = filepath.LastIndexOf("/");
            string  localFileName = filepath.Substring(index1 + 1);
            logdata.LOCALFILENAME = localFileName;
            logdata.ORIGINALURL = ORIGINALURL;
            WriteDownLoadLog();
        }
   // 文件按照二進制流循環輸出。其實沒必要這麼寫。
        public void outputBinary(string fileName, string filepath, HttpContext context)
        ...{

            context.Response.ContentType = "application/octet-stream";
            context.Response.AppendHeader("Content-Disposition", "attachment; filename=" + fileName);
            using (System.IO.FileStream fs = new System.IO.FileStream(filepath, System.IO.FileMode.Open, System.IO.FileAccess.Read))
            ...{
                byte[] aLogData = new byte[1024];
                int len;
                //設定每次讀取1024個字節。避免多人下載時過慢。
                while ((len = fs.Read(aLogData, 0, aLogData.Length)) > 0)
                ...{
                    context.Response.BinaryWrite(_FixBuffer(aLogData, len));
                }
            }

        }
        /**//// <summary>
        /// 取指定長度的文件
        /// </summary>
        /// <param name="aLogData"></param>
        /// <param name="len"></param>
        /// <returns></returns>
        private byte[] _FixBuffer(byte[] aLogData, int len)
        ...{
            if (aLogData.Length == len)
                return aLogData;

            byte[] buffer = new byte[len];
            Array.Copy(aLogData, buffer, len);
            return buffer;
        }
        public bool IsReusable
        ...{
            get
            ...{
                return true;
            }
        }
}

 

2：配置webconfitg

<httpHandlers>

<!--當請求的後綴爲.cab的時候，調用DownloadFileProcesser這個繼承IHttpHandler接口的類-!>
   <add verb="GET,POST" path="*.cab" type="DownloadFileProcesser"/>
  </httpHandlers>

3：運行IIS服務管理器，右鍵點擊默認Web站點，選擇屬性，移動到Home目錄選項頁，並點擊配置按鈕。應用程序配置對話框彈出來了。點擊添加按鈕並在可執行字段輸入aspnet_isapi.dll文件路徑，在擴展字段輸入.kim
ps:如果你的操作系統是XP SP2的話，在輸入aspnet_isapi.dll路徑時需要手工輸入，不能用複製粘貼的形式，否則保存按鈕變灰。瀏覽時去掉check file exit選項。