/// <summary>
        /// 下載文件
        /// </summary>
        /// <param name="url">下載地址</param>
        /// <param name="path">本地路徑</param>
        public static bool DownLoadFile(string url, string path)
        {bool flag = false;
            long SPosition = 0;
            FileStream FStream = null;
            Stream myStream = null;

            try
            {
                //判斷要下載的文件是否存在
                if (File.Exists(path))
                {
                    //打開上次下載的文件
                    FStream = File.OpenWrite(path);
                    //獲取已經下載的長度
                    SPosition = FStream.Length;
                    long serverFileLength = GetHttpLength(url);
                    if (serverFileLength == -1)
                    {
                        //本地文件
                        return true;
                    }
                    if (serverFileLength == 0)
                    {
                        return false;
                    }
                    if (SPosition == serverFileLength)
                    {
                        //文件是完整的，直接結束下載任務
                        return true;
                    }
                    if (SPosition > serverFileLength)
                    {
                        SPosition = 0;
                        FStream.Seek(0, SeekOrigin.Current);
                    }
                    else
                    {
                        FStream.Seek(SPosition, SeekOrigin.Current);
                    }
                }
                else
                {
                    FStream = new FileStream(path, FileMode.Create);
                    SPosition = 0;
                }

                //打開網絡連接
                HttpWebRequest myRequest = (HttpWebRequest)HttpWebRequest.Create(url);
                if (SPosition > 0)
                {
                    //設置Range值
                    myRequest.AddRange(SPosition);
                }
                //向服務器請求,獲得服務器的回應數據流
                myStream = myRequest.GetResponse().GetResponseStream();
                //定義一個位元組數據
                byte[] btContent = new byte[512];
                int intSize = 0;
                intSize = myStream.Read(btContent, 0, 512);
                while (intSize > 0)
                {
                    FStream.Write(btContent, 0, intSize);
                    intSize = myStream.Read(btContent, 0, 512);
                }
                flag = true;
            }
            catch (Exception ex)
            {
                flag = false;
                LogApi.WriteLog("下載文件時異常:" + path);
                LogApi.WriteErrLog(ex);
            }
            finally
            {
                //關閉流
                if (myStream != null)
                {
                    myStream.Close();
                    myStream.Dispose();
                }
                if (FStream != null)
                {
                    FStream.Close();
                    FStream.Dispose();
                }
            }
            return flag;
        }