.net文件上传时实现通过文件头确认文件类型的方法

AppCode/FileUpload.csusing System;using System.Collections.Generic;using System.IO;using System.Text;using System.Text.RegularExpressions;using System.Web;/// <summary>/// FileHeader 的摘要说明/// </summary>public static class FileUpload{  private static string script = string.Empty;  private static bool autonamed = true;  private static Random ra = new Random();  public static bool AutoNamed  {    get    {      return autonamed;    }    set    {      autonamed = value;    }  }  public static string Script  {    get    {      return "var upload = [" + script + "];";    }  }  public static Dictionary<string, byte[]> ImageHeader = new Dictionary<string, byte[]>();  public static Dictionary<string, object> FilesHeader = new Dictionary<string, object>();    static FileUpload() {    ImageHeader.Add("gif", new byte[] { 71, 73, 70, 56, 57, 97 });    ImageHeader.Add("bmp", new byte[] { 66, 77 });    ImageHeader.Add("jpg", new byte[] { 255, 216, 255 });    ImageHeader.Add("png", new byte[] { 137, 80, 78, 71, 13, 10, 26, 10, 0, 0, 0, 13, 73, 72, 68, 82 });    FilesHeader.Add("pdf", new byte[] { 37, 80, 68, 70, 45, 49, 46, 53 });    FilesHeader.Add("docx", new object[] { new byte[] { 80, 75, 3, 4, 20, 0, 6, 0, 8, 0, 0, 0, 33 }, new Regex(@"word/_rels/document/.xml/.rels", RegexOptions.IgnoreCase) });    FilesHeader.Add("xlsx", new object[] { new byte[] { 80, 75, 3, 4, 20, 0, 6, 0, 8, 0, 0, 0, 33 }, new Regex(@"xl/_rels/workbook/.xml/.rels", RegexOptions.IgnoreCase) });    FilesHeader.Add("pptx", new object[] { new byte[] { 80, 75, 3, 4, 20, 0, 6, 0, 8, 0, 0, 0, 33 }, new Regex(@"ppt/_rels/presentation/.xml/.rels", RegexOptions.IgnoreCase) });    FilesHeader.Add("doc", new object[] { new byte[] { 208, 207, 17, 224, 161, 177, 26, 225 }, new Regex(@"microsoft( office)? word(?![/s/S]*?microsoft)", RegexOptions.IgnoreCase) });    FilesHeader.Add("xls", new object[] { new byte[] { 208, 207, 17, 224, 161, 177, 26, 225 }, new Regex(@"microsoft( office)? excel(?![/s/S]*?microsoft)", RegexOptions.IgnoreCase) });    FilesHeader.Add("ppt", new object[] { new byte[] { 208, 207, 17, 224, 161, 177, 26, 225 }, new Regex(@"c.u.r.r.e.n.t. .u.s.e.r(?![/s/S]*?[a-z])", RegexOptions.IgnoreCase) });    FilesHeader.Add("avi", new byte[] { 65, 86, 73, 32 });    FilesHeader.Add("mpg", new byte[] { 0, 0, 1, 0xBA });    FilesHeader.Add("mpeg", new byte[] { 0, 0, 1, 0xB3 });    FilesHeader.Add("rar", new byte[] { 82, 97, 114, 33, 26, 7 });    FilesHeader.Add("zip", new byte[] { 80, 75, 3, 4 });  }  private static string DateTimeStamp()  {    return DateTime.Now.ToString("yyyyMMddHHmmss") + ra.Next(0, 99999).ToString("00000");  }  private static string FileType(Stream str)  {    string FileExt = string.Empty;    foreach (string ext in FilesHeader.Keys)    {      byte[] header = FilesHeader[ext].GetType() == (new byte[] { }).GetType() ? (byte[])FilesHeader[ext] : (byte[])(((object[])FilesHeader[ext])[0]);      byte[] test = new byte[header.Length];      str.Position = 0;      str.Read(test, 0, test.Length);      bool same = true;      for (int i = 0; i < test.Length; i++)      {        if (test[i] != header[i])        {          same = false;          break;        }      }      if (FilesHeader[ext].GetType() != (new byte[] { }).GetType() && same)      {        object[] obj = (object[])FilesHeader[ext];        bool exists = false;        if (obj[1].GetType().ToString() == "System.Int32")        {          for (int ii = 2; ii < obj.Length; ii++)          {            if (str.Length >= (int)obj[1])            {              str.Position = str.Length - (int)obj[1];              byte[] more = (byte[])obj[ii];              byte[] testmore = new byte[more.Length];              str.Read(testmore, 0, testmore.Length);              if (Encoding.GetEncoding(936).GetString(more) == Encoding.GetEncoding(936).GetString(testmore))              {                exists = true;                break;              }            }          }        }        else if (obj[1].GetType().ToString() == "System.Text.RegularExpressions.Regex")        {          Regex re = (Regex)obj[1];          str.Position = 0;          byte[] buffer = new byte[(int)str.Length];          str.Read(buffer, 0, buffer.Length);          string txt = Encoding.ASCII.GetString(buffer);          if (re.IsMatch(txt))          {            exists = true;          }        }        if (!exists)        {          same = false;        }      }      if (same)      {        FileExt = ext;        break;      }    }    return FileExt;  }  private static string ImageType(Stream str)  {    string FileExt = string.Empty;    foreach (string ext in ImageHeader.Keys)    {      byte[] header = ImageHeader[ext];      byte[] test = new byte[header.Length];      str.Position = 0;      str.Read(test, 0, test.Length);      bool same = true;      for (int i = 0; i < test.Length; i++)      {        if (test[i] != header[i])        {          same = false;          break;        }      }      if (same)      {        FileExt = ext;        break;      }    }    if (!string.IsNullOrEmpty(FileExt))    {      Encoding[] chkList = new Encoding[] { Encoding.ASCII, Encoding.UTF8, Encoding.GetEncoding(936) };      for (int i = 0; i < chkList.Length; i++)      {        str.Position = 0;        string str_test = new StreamReader(str, chkList[i]).ReadToEnd();        if (Regex.IsMatch(str_test, @"^[^/u0000-/u0008/u000B-/u000C/u000E-/u001F]*$"))        {          FileExt = string.Empty;          break;        }      }    }    return FileExt;  }  private static void CreateFolder(string path)  {    string t_path = HttpContext.Current.Server.MapPath(path);    if (!Directory.Exists(t_path))    {      Directory.CreateDirectory(t_path);    }  }  private static string CreateFileName(string name, string ext)  {    string filename = "/Upload/" + DateTime.Now.ToString("yyyy/MM/dd") + "/" + ext + "/" + (autonamed ? DateTimeStamp() + "." + ext : name);    if (File.Exists(HttpContext.Current.Server.MapPath(filename)))    {      return CreateFileName(name, ext);    }    else    {      return filename;    }  }  private static string SaveAs(HttpPostedFile file, string Ext)  {    string filename = CreateFileName(file.FileName, Ext);    CreateFolder(Regex.Match(filename, @"^[/s/S]*?(?=[^///]+$)").Value);    file.SaveAs(HttpContext.Current.Server.MapPath(filename));    return Regex.Match(HttpContext.Current.Request.Url.ToString(), @"^[/s/S]*?(?=(?<!/)/(?!/))").Value + filename;  }  private static void SaveInvalid(HttpPostedFile file)  {  }  // 每次提交之前调用此方法，确认返回内容正确  public static void Clear()  {    script = string.Empty;  }  public static void Save(HttpPostedFile file)  {    if (file.ContentLength == 0)    {      if (file.FileName.Length > 0)      {        script += (script.Length > 0 ? "," : "") + "{filename:'" + file.FileName + "',upload:false,length:0,target:null,type:''}";      }    }    else    {      if (Regex.IsMatch(file.ContentType, @"^image/"))      {        string ext = ImageType(file.InputStream);        if (string.IsNullOrEmpty(ext))        {          SaveInvalid(file);          script += (script.Length > 0 ? "," : "") + "{filename:'" + file.FileName + "',upload:false,length:" + file.ContentLength + ",target:null,type:''}";        }        else        {          string filename = SaveAs(file, ext);          script += (script.Length > 0 ? "," : "") + "{filename:'" + file.FileName + "',upload:true,length:" + file.ContentLength + ",target:'" + filename + "',type:'" + ext + "'}";        }      }      else if (Regex.IsMatch(file.ContentType, @"^text/"))      {      }      else      {        string ext = FileType(file.InputStream);        if (string.IsNullOrEmpty(ext))        {          SaveInvalid(file);          script += (script.Length > 0 ? "," : "") + "{filename:'" + file.FileName + "',upload:false,length:" + file.ContentLength + ",target:null,type:'',header:[" + "" + "]}";        }        else        {          string filename = SaveAs(file, ext);          script += (script.Length > 0 ? "," : "") + "{filename:'" + file.FileName + "',upload:true,length:" + file.ContentLength + ",target:'" + filename + "',type:'" + ext + "'}";        }      }    }  }}

using System;using System.Web;public partial class _Default : System.Web.UI.Page{  protected void Page_Load(object sender, EventArgs e)  {    HttpFileCollection files = Request.Files;    FileUpload.Clear();    for (int i = 0; i < files.Count; i++)    {      FileUpload.Save(files[i]);    }    Response.Write(FileUpload.Script);  }}