文档和视频文件格式的后缀名验证以及图片的真实验证帮助类

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
namespace Reform.FolderManage.Cls
{
    public class FileHelper
    {

        /// <summary>
        /// 图片类型头部编码
        /// </summary>
        public enum ImgExtension
        {
            JPG = 255216,
            GIF = 7173,
            BMP = 6677,
            PNG = 13780
        }
        /// <summary>
        /// 文件类型的判断
        /// </summary>
        /// <param name="fileName">文件</param>
        /// <param name="fileType">文件类型</param>
        /// <returns></returns>
        public static bool IsRealFile(string fileName, string fileType)
        {
            string fileExt = Path.GetExtension(fileName).ToLower();//取得文件后缀名
            if (fileType == "图片")
            {
                if (IsAllowedExtension(fileName)) return true;
            }
            if (fileType == "视频")
            {
                List<string> list = new List<string>();
                list.Add(".flv");
                list.Add(".wmv");
                list.Add(".avi");
                list.Add(".3gp");
                Path.GetExtension(fileName).ToLower();//取得文件后缀名
                return IsExistEx(list, fileExt);
            }
            if (fileType == "文档")
            {
                List<string> list = new List<string>();
                list.Add(".doc");
                list.Add(".pdf");
                return IsExistEx(list, fileExt);
            }
            return false;
        }
        /// <summary>
        /// 判断文件后缀
        /// </summary>
        private static bool IsExistEx(List<string> list, string fileExt)
        {
            if (list.Contains(fileExt))//在列表中
            {
                return true;
            }
            return false;
        }
         
        #region 图片处理
        /// <summary>
        /// 是否是真实的图片类型
        /// </summary>
        public static bool IsAllowedExtension(string imgFileName)
        {
            System.IO.FileStream fs = new System.IO.FileStream(imgFileName, System.IO.FileMode.Open, System.IO.FileAccess.Read);
            System.IO.BinaryReader br = new System.IO.BinaryReader(fs);
            string fileclass = "";
            byte buffer;
            try
            {
                buffer = br.ReadByte();
                fileclass = buffer.ToString();
                buffer = br.ReadByte();
                fileclass += buffer.ToString();
            }
            catch { }
            br.Close();
            fs.Close();
            ImgExtension[] fileEx = { ImgExtension.BMP, ImgExtension.GIF, ImgExtension.JPG, ImgExtension.PNG };
            foreach (ImgExtension fe in fileEx)
            {
                if (Int32.Parse(fileclass) == (int)fe) return true;
            }
            return false;
        }
        #endregion




      
    }
}