/// <summary>
/// 构造函数
/// </summary>
/// <param name="uploadconfig">参数配置如：PMG（PMG_Extn：允许上传的后缀【.GIF|.JPEG|.JPE】，PMG_MaxFileLength：允许上传的最大长度K）</param>
public FileUpload(string uploadconfig)
{
UploadConfig = uploadconfig;
Filter = string.IsNullOrEmpty(TextHelper.GetConfigItem(UploadConfig + "_Extn")) ? ".GIF|.JPEG|.JPE|.JPG|.PNG|.BMP|.TIFF|.TIF|.SWF" : TextHelper.GetConfigItem(UploadConfig + "_Extn");
MaxFileLength = TextHelper.GetConfigItem(UploadConfig + "_MaxFileLength") == null ? 4096 : long.Parse(TextHelper.GetConfigItem(UploadConfig + "_MaxFileLength"));
}