/// <summary>
/// 讀取大檔案,每次讀取1M,優化可考慮分割讀取
/// </summary>
/// <returns></returns>
public static string ReadBinaryFileToString(FileStream fs)
{
    if (fs != null)
    {
        string returnStr = ""; //儲存結果字串
        try
        {
            byte[] byteArray = new byte[1024 * 1024];//開闢1M記憶體空間

            BinaryReader reader = new BinaryReader(fs);

            while (reader.Read(byteArray, 0, byteArray.Length) > 0)
            {
                string content = AppTool.DEFAULT_FILE_ENCODING.GetString(byteArray);
                returnStr += content;
            }

            return returnStr;
        }
        catch (Exception e)
        {
            Debug.WriteLine(string.Format("讀取檔案出錯：訊息={0},堆疊={1}", e.Message, e.StackTrace));
        }          
    }
    return null;
}