/// <summary>
        /// 下載方法
        /// </summary>
        /// <param name="uri">下載地址的URI</param>
        public void DownLoad(object obj)
        {

            //比如uri=http://localhost/Rabom/1.rar;iis就需要自己配置了。
            string uri = obj.ToString();
            //截取文件名
            string fileName = uri.Substring(uri.LastIndexOf(@"/") + 1);

            //構(gòu)造文件完全限定名,準(zhǔn)備將網(wǎng)絡(luò)流下載為本地文件
            string fileFullName = Application.StartupPath + @"\download\" + fileName;
            //構(gòu)造文件的配置文件的完全完全限定名
            string fileCfgName = Application.StartupPath + @"\download\" + fileName+".cfg";

            //本地構(gòu)造文件流
            FileStream fs;
            //本地配置文件流
            FileStream fsCfg;

            if (File.Exists(fileFullName))
            {
                //如果存在配置文件，則繼續(xù)下載
                if (File.Exists(fileCfgName))
                {
                    fs = new FileStream(fileFullName, FileMode.Append, FileAccess.Write, FileShare.Write);
                    fsCfg = fs = new FileStream(fileFullName, FileMode.Append, FileAccess.Write, FileShare.Write);
                }
                else
                {
                    return;//暫且這樣
                }
            }
            else
            {
                fs = new FileStream(fileFullName, FileMode.Create);
                fsCfg = new FileStream(fileCfgName, FileMode.Create);
            }

            //開辟內(nèi)存空間
            byte[] buffer = new byte[512];

            //請求地址
            HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(uri);
            //請求開始位置
            request.AddRange((int)fs.Length);

            //獲取網(wǎng)絡(luò)流
            Stream ns = request.GetResponse().GetResponseStream();

            //獲取文件實(shí)際長度
            long contentLength = request.GetResponse().ContentLength;
            //獲取文件讀取到的長度
            int length = ns.Read(buffer, 0, buffer.Length);

            while (length > 0)
            {   

                //將字節(jié)數(shù)組寫入流
                fs.Write(buffer, 0, buffer.Length);

                //繼續(xù)下載
                buffer = new byte[512];
                length = ns.Read(buffer, 0, buffer.Length);
            }

            ns.Close();
            fs.Close();
            fsCfg.Close();

     }