我正在寻找一种简单的方法来获得mime类型，其中文件扩展名是不正确的或没有给出，类似于这个问题只有在. net。
当前回答
我使用混合解决方案:
using System.Runtime.InteropServices;
[DllImport (@"urlmon.dll", CharSet = CharSet.Auto)]
private extern static System.UInt32 FindMimeFromData(
System.UInt32 pBC,
[MarshalAs(UnmanagedType.LPStr)] System.String pwzUrl,
[MarshalAs(UnmanagedType.LPArray)] byte[] pBuffer,
System.UInt32 cbSize,
[MarshalAs(UnmanagedType.LPStr)] System.String pwzMimeProposed,
System.UInt32 dwMimeFlags,
out System.UInt32 ppwzMimeOut,
System.UInt32 dwReserverd
);
private string GetMimeFromRegistry (string Filename)
{
string mime = "application/octetstream";
string ext = System.IO.Path.GetExtension(Filename).ToLower();
Microsoft.Win32.RegistryKey rk = Microsoft.Win32.Registry.ClassesRoot.OpenSubKey(ext);
if (rk != null && rk.GetValue("Content Type") != null)
mime = rk.GetValue("Content Type").ToString();
return mime;
}
public string GetMimeTypeFromFileAndRegistry (string filename)
{
if (!File.Exists(filename))
{
return GetMimeFromRegistry (filename);
}
byte[] buffer = new byte[256];
using (FileStream fs = new FileStream(filename, FileMode.Open))
{
if (fs.Length >= 256)
fs.Read(buffer, 0, 256);
else
fs.Read(buffer, 0, (int)fs.Length);
}
try
{
System.UInt32 mimetype;
FindMimeFromData(0, null, buffer, 256, null, 0, out mimetype, 0);
System.IntPtr mimeTypePtr = new IntPtr(mimetype);
string mime = Marshal.PtrToStringUni(mimeTypePtr);
Marshal.FreeCoTaskMem(mimeTypePtr);
if (string.IsNullOrWhiteSpace (mime) ||
mime =="text/plain" || mime == "application/octet-stream")
{
return GetMimeFromRegistry (filename);
}
return mime;
}
catch (Exception e)
{
return GetMimeFromRegistry (filename);
}
}
其他回答
你好，我已经改编了Winista。MimeDetect项目到。net core/framework，回退到urlmon.dll，自由使用它:nuget包。
//init
var mimeTypes = new MimeTypes();
//usage by filepath
var mimeType1 = mimeTypes.GetMimeTypeFromFile(filePath);
我找到了一个硬编码的解决方案，我希望我能帮助到别人:
public static class MIMEAssistant
{
private static readonly Dictionary<string, string> MIMETypesDictionary = new Dictionary<string, string>
{
{"ai", "application/postscript"},
{"aif", "audio/x-aiff"},
{"aifc", "audio/x-aiff"},
{"aiff", "audio/x-aiff"},
{"asc", "text/plain"},
{"atom", "application/atom+xml"},
{"au", "audio/basic"},
{"avi", "video/x-msvideo"},
{"bcpio", "application/x-bcpio"},
{"bin", "application/octet-stream"},
{"bmp", "image/bmp"},
{"cdf", "application/x-netcdf"},
{"cgm", "image/cgm"},
{"class", "application/octet-stream"},
{"cpio", "application/x-cpio"},
{"cpt", "application/mac-compactpro"},
{"csh", "application/x-csh"},
{"css", "text/css"},
{"dcr", "application/x-director"},
{"dif", "video/x-dv"},
{"dir", "application/x-director"},
{"djv", "image/vnd.djvu"},
{"djvu", "image/vnd.djvu"},
{"dll", "application/octet-stream"},
{"dmg", "application/octet-stream"},
{"dms", "application/octet-stream"},
{"doc", "application/msword"},
{"docx","application/vnd.openxmlformats-officedocument.wordprocessingml.document"},
{"dotx", "application/vnd.openxmlformats-officedocument.wordprocessingml.template"},
{"docm","application/vnd.ms-word.document.macroEnabled.12"},
{"dotm","application/vnd.ms-word.template.macroEnabled.12"},
{"dtd", "application/xml-dtd"},
{"dv", "video/x-dv"},
{"dvi", "application/x-dvi"},
{"dxr", "application/x-director"},
{"eps", "application/postscript"},
{"etx", "text/x-setext"},
{"exe", "application/octet-stream"},
{"ez", "application/andrew-inset"},
{"gif", "image/gif"},
{"gram", "application/srgs"},
{"grxml", "application/srgs+xml"},
{"gtar", "application/x-gtar"},
{"hdf", "application/x-hdf"},
{"hqx", "application/mac-binhex40"},
{"htm", "text/html"},
{"html", "text/html"},
{"ice", "x-conference/x-cooltalk"},
{"ico", "image/x-icon"},
{"ics", "text/calendar"},
{"ief", "image/ief"},
{"ifb", "text/calendar"},
{"iges", "model/iges"},
{"igs", "model/iges"},
{"jnlp", "application/x-java-jnlp-file"},
{"jp2", "image/jp2"},
{"jpe", "image/jpeg"},
{"jpeg", "image/jpeg"},
{"jpg", "image/jpeg"},
{"js", "application/x-javascript"},
{"kar", "audio/midi"},
{"latex", "application/x-latex"},
{"lha", "application/octet-stream"},
{"lzh", "application/octet-stream"},
{"m3u", "audio/x-mpegurl"},
{"m4a", "audio/mp4a-latm"},
{"m4b", "audio/mp4a-latm"},
{"m4p", "audio/mp4a-latm"},
{"m4u", "video/vnd.mpegurl"},
{"m4v", "video/x-m4v"},
{"mac", "image/x-macpaint"},
{"man", "application/x-troff-man"},
{"mathml", "application/mathml+xml"},
{"me", "application/x-troff-me"},
{"mesh", "model/mesh"},
{"mid", "audio/midi"},
{"midi", "audio/midi"},
{"mif", "application/vnd.mif"},
{"mov", "video/quicktime"},
{"movie", "video/x-sgi-movie"},
{"mp2", "audio/mpeg"},
{"mp3", "audio/mpeg"},
{"mp4", "video/mp4"},
{"mpe", "video/mpeg"},
{"mpeg", "video/mpeg"},
{"mpg", "video/mpeg"},
{"mpga", "audio/mpeg"},
{"ms", "application/x-troff-ms"},
{"msh", "model/mesh"},
{"mxu", "video/vnd.mpegurl"},
{"nc", "application/x-netcdf"},
{"oda", "application/oda"},
{"ogg", "application/ogg"},
{"pbm", "image/x-portable-bitmap"},
{"pct", "image/pict"},
{"pdb", "chemical/x-pdb"},
{"pdf", "application/pdf"},
{"pgm", "image/x-portable-graymap"},
{"pgn", "application/x-chess-pgn"},
{"pic", "image/pict"},
{"pict", "image/pict"},
{"png", "image/png"},
{"pnm", "image/x-portable-anymap"},
{"pnt", "image/x-macpaint"},
{"pntg", "image/x-macpaint"},
{"ppm", "image/x-portable-pixmap"},
{"ppt", "application/vnd.ms-powerpoint"},
{"pptx","application/vnd.openxmlformats-officedocument.presentationml.presentation"},
{"potx","application/vnd.openxmlformats-officedocument.presentationml.template"},
{"ppsx","application/vnd.openxmlformats-officedocument.presentationml.slideshow"},
{"ppam","application/vnd.ms-powerpoint.addin.macroEnabled.12"},
{"pptm","application/vnd.ms-powerpoint.presentation.macroEnabled.12"},
{"potm","application/vnd.ms-powerpoint.template.macroEnabled.12"},
{"ppsm","application/vnd.ms-powerpoint.slideshow.macroEnabled.12"},
{"ps", "application/postscript"},
{"qt", "video/quicktime"},
{"qti", "image/x-quicktime"},
{"qtif", "image/x-quicktime"},
{"ra", "audio/x-pn-realaudio"},
{"ram", "audio/x-pn-realaudio"},
{"ras", "image/x-cmu-raster"},
{"rdf", "application/rdf+xml"},
{"rgb", "image/x-rgb"},
{"rm", "application/vnd.rn-realmedia"},
{"roff", "application/x-troff"},
{"rtf", "text/rtf"},
{"rtx", "text/richtext"},
{"sgm", "text/sgml"},
{"sgml", "text/sgml"},
{"sh", "application/x-sh"},
{"shar", "application/x-shar"},
{"silo", "model/mesh"},
{"sit", "application/x-stuffit"},
{"skd", "application/x-koan"},
{"skm", "application/x-koan"},
{"skp", "application/x-koan"},
{"skt", "application/x-koan"},
{"smi", "application/smil"},
{"smil", "application/smil"},
{"snd", "audio/basic"},
{"so", "application/octet-stream"},
{"spl", "application/x-futuresplash"},
{"src", "application/x-wais-source"},
{"sv4cpio", "application/x-sv4cpio"},
{"sv4crc", "application/x-sv4crc"},
{"svg", "image/svg+xml"},
{"swf", "application/x-shockwave-flash"},
{"t", "application/x-troff"},
{"tar", "application/x-tar"},
{"tcl", "application/x-tcl"},
{"tex", "application/x-tex"},
{"texi", "application/x-texinfo"},
{"texinfo", "application/x-texinfo"},
{"tif", "image/tiff"},
{"tiff", "image/tiff"},
{"tr", "application/x-troff"},
{"tsv", "text/tab-separated-values"},
{"txt", "text/plain"},
{"ustar", "application/x-ustar"},
{"vcd", "application/x-cdlink"},
{"vrml", "model/vrml"},
{"vxml", "application/voicexml+xml"},
{"wav", "audio/x-wav"},
{"wbmp", "image/vnd.wap.wbmp"},
{"wbmxl", "application/vnd.wap.wbxml"},
{"wml", "text/vnd.wap.wml"},
{"wmlc", "application/vnd.wap.wmlc"},
{"wmls", "text/vnd.wap.wmlscript"},
{"wmlsc", "application/vnd.wap.wmlscriptc"},
{"wrl", "model/vrml"},
{"xbm", "image/x-xbitmap"},
{"xht", "application/xhtml+xml"},
{"xhtml", "application/xhtml+xml"},
{"xls", "application/vnd.ms-excel"},
{"xml", "application/xml"},
{"xpm", "image/x-xpixmap"},
{"xsl", "application/xml"},
{"xlsx","application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"},
{"xltx","application/vnd.openxmlformats-officedocument.spreadsheetml.template"},
{"xlsm","application/vnd.ms-excel.sheet.macroEnabled.12"},
{"xltm","application/vnd.ms-excel.template.macroEnabled.12"},
{"xlam","application/vnd.ms-excel.addin.macroEnabled.12"},
{"xlsb","application/vnd.ms-excel.sheet.binary.macroEnabled.12"},
{"xslt", "application/xslt+xml"},
{"xul", "application/vnd.mozilla.xul+xml"},
{"xwd", "image/x-xwindowdump"},
{"xyz", "chemical/x-xyz"},
{"zip", "application/zip"}
};
public static string GetMIMEType(string fileName)
{
//get file extension
string extension = Path.GetExtension(fileName).ToLowerInvariant();
if (extension.Length > 0 &&
MIMETypesDictionary.ContainsKey(extension.Remove(0, 1)))
{
return MIMETypesDictionary[extension.Remove(0, 1)];
}
return "unknown/unknown";
}
}
编辑:只需使用Mime侦探
我使用字节数组序列来确定给定文件的正确MIME类型。与只查看文件名的文件扩展名相比，这样做的好处是，如果用户要重命名一个文件以绕过某些文件类型的上传限制，则文件扩展名将无法捕捉到这一点。另一方面，通过字节数组获取文件签名将阻止这种有害行为的发生。
下面是c#中的一个例子:
public class MimeType
{
private static readonly byte[] BMP = { 66, 77 };
private static readonly byte[] DOC = { 208, 207, 17, 224, 161, 177, 26, 225 };
private static readonly byte[] EXE_DLL = { 77, 90 };
private static readonly byte[] GIF = { 71, 73, 70, 56 };
private static readonly byte[] ICO = { 0, 0, 1, 0 };
private static readonly byte[] JPG = { 255, 216, 255 };
private static readonly byte[] MP3 = { 255, 251, 48 };
private static readonly byte[] OGG = { 79, 103, 103, 83, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0 };
private static readonly byte[] PDF = { 37, 80, 68, 70, 45, 49, 46 };
private static readonly byte[] PNG = { 137, 80, 78, 71, 13, 10, 26, 10, 0, 0, 0, 13, 73, 72, 68, 82 };
private static readonly byte[] RAR = { 82, 97, 114, 33, 26, 7, 0 };
private static readonly byte[] SWF = { 70, 87, 83 };
private static readonly byte[] TIFF = { 73, 73, 42, 0 };
private static readonly byte[] TORRENT = { 100, 56, 58, 97, 110, 110, 111, 117, 110, 99, 101 };
private static readonly byte[] TTF = { 0, 1, 0, 0, 0 };
private static readonly byte[] WAV_AVI = { 82, 73, 70, 70 };
private static readonly byte[] WMV_WMA = { 48, 38, 178, 117, 142, 102, 207, 17, 166, 217, 0, 170, 0, 98, 206, 108 };
private static readonly byte[] ZIP_DOCX = { 80, 75, 3, 4 };
public static string GetMimeType(byte[] file, string fileName)
{
string mime = "application/octet-stream"; //DEFAULT UNKNOWN MIME TYPE
//Ensure that the filename isn't empty or null
if (string.IsNullOrWhiteSpace(fileName))
{
return mime;
}
//Get the file extension
string extension = Path.GetExtension(fileName) == null
? string.Empty
: Path.GetExtension(fileName).ToUpper();
//Get the MIME Type
if (file.Take(2).SequenceEqual(BMP))
{
mime = "image/bmp";
}
else if (file.Take(8).SequenceEqual(DOC))
{
mime = "application/msword";
}
else if (file.Take(2).SequenceEqual(EXE_DLL))
{
mime = "application/x-msdownload"; //both use same mime type
}
else if (file.Take(4).SequenceEqual(GIF))
{
mime = "image/gif";
}
else if (file.Take(4).SequenceEqual(ICO))
{
mime = "image/x-icon";
}
else if (file.Take(3).SequenceEqual(JPG))
{
mime = "image/jpeg";
}
else if (file.Take(3).SequenceEqual(MP3))
{
mime = "audio/mpeg";
}
else if (file.Take(14).SequenceEqual(OGG))
{
if (extension == ".OGX")
{
mime = "application/ogg";
}
else if (extension == ".OGA")
{
mime = "audio/ogg";
}
else
{
mime = "video/ogg";
}
}
else if (file.Take(7).SequenceEqual(PDF))
{
mime = "application/pdf";
}
else if (file.Take(16).SequenceEqual(PNG))
{
mime = "image/png";
}
else if (file.Take(7).SequenceEqual(RAR))
{
mime = "application/x-rar-compressed";
}
else if (file.Take(3).SequenceEqual(SWF))
{
mime = "application/x-shockwave-flash";
}
else if (file.Take(4).SequenceEqual(TIFF))
{
mime = "image/tiff";
}
else if (file.Take(11).SequenceEqual(TORRENT))
{
mime = "application/x-bittorrent";
}
else if (file.Take(5).SequenceEqual(TTF))
{
mime = "application/x-font-ttf";
}
else if (file.Take(4).SequenceEqual(WAV_AVI))
{
mime = extension == ".AVI" ? "video/x-msvideo" : "audio/x-wav";
}
else if (file.Take(16).SequenceEqual(WMV_WMA))
{
mime = extension == ".WMA" ? "audio/x-ms-wma" : "video/x-ms-wmv";
}
else if (file.Take(4).SequenceEqual(ZIP_DOCX))
{
mime = extension == ".DOCX" ? "application/vnd.openxmlformats-officedocument.wordprocessingml.document" : "application/x-zip-compressed";
}
return mime;
}
}
注意，我对DOCX文件类型的处理是不同的，因为DOCX实际上只是一个ZIP文件。在这个场景中，只要验证了文件扩展名的顺序，我就会检查文件扩展名。对于某些人来说，这个示例还远远不够完整，但是您可以轻松地添加自己的示例。
如果您想添加更多MIME类型，您可以从这里获得许多不同文件类型的字节数组序列。另外，这里还有一个关于文件签名的很好的资源。
如果其他方法都失败了，我经常做的是逐步查看我正在寻找的特定类型的几个文件，并在文件的字节序列中寻找模式。最后，这仍然是基本的验证，不能用于确定文件类型的100%证明。
我发现这个很有用。 VB。NET开发人员:
Public Shared Function GetFromFileName(ByVal fileName As String) As String
Return GetFromExtension(Path.GetExtension(fileName).Remove(0, 1))
End Function
Public Shared Function GetFromExtension(ByVal extension As String) As String
If extension.StartsWith("."c) Then
extension = extension.Remove(0, 1)
End If
If MIMETypesDictionary.ContainsKey(extension) Then
Return MIMETypesDictionary(extension)
End If
Return "unknown/unknown"
End Function
Private Shared ReadOnly MIMETypesDictionary As New Dictionary(Of String, String)() From { _
{"ai", "application/postscript"}, _
{"aif", "audio/x-aiff"}, _
{"aifc", "audio/x-aiff"}, _
{"aiff", "audio/x-aiff"}, _
{"asc", "text/plain"}, _
{"atom", "application/atom+xml"}, _
{"au", "audio/basic"}, _
{"avi", "video/x-msvideo"}, _
{"bcpio", "application/x-bcpio"}, _
{"bin", "application/octet-stream"}, _
{"bmp", "image/bmp"}, _
{"cdf", "application/x-netcdf"}, _
{"cgm", "image/cgm"}, _
{"class", "application/octet-stream"}, _
{"cpio", "application/x-cpio"}, _
{"cpt", "application/mac-compactpro"}, _
{"csh", "application/x-csh"}, _
{"css", "text/css"}, _
{"dcr", "application/x-director"}, _
{"dif", "video/x-dv"}, _
{"dir", "application/x-director"}, _
{"djv", "image/vnd.djvu"}, _
{"djvu", "image/vnd.djvu"}, _
{"dll", "application/octet-stream"}, _
{"dmg", "application/octet-stream"}, _
{"dms", "application/octet-stream"}, _
{"doc", "application/msword"}, _
{"dtd", "application/xml-dtd"}, _
{"dv", "video/x-dv"}, _
{"dvi", "application/x-dvi"}, _
{"dxr", "application/x-director"}, _
{"eps", "application/postscript"}, _
{"etx", "text/x-setext"}, _
{"exe", "application/octet-stream"}, _
{"ez", "application/andrew-inset"}, _
{"gif", "image/gif"}, _
{"gram", "application/srgs"}, _
{"grxml", "application/srgs+xml"}, _
{"gtar", "application/x-gtar"}, _
{"hdf", "application/x-hdf"}, _
{"hqx", "application/mac-binhex40"}, _
{"htm", "text/html"}, _
{"html", "text/html"}, _
{"ice", "x-conference/x-cooltalk"}, _
{"ico", "image/x-icon"}, _
{"ics", "text/calendar"}, _
{"ief", "image/ief"}, _
{"ifb", "text/calendar"}, _
{"iges", "model/iges"}, _
{"igs", "model/iges"}, _
{"jnlp", "application/x-java-jnlp-file"}, _
{"jp2", "image/jp2"}, _
{"jpe", "image/jpeg"}, _
{"jpeg", "image/jpeg"}, _
{"jpg", "image/jpeg"}, _
{"js", "application/x-javascript"}, _
{"kar", "audio/midi"}, _
{"latex", "application/x-latex"}, _
{"lha", "application/octet-stream"}, _
{"lzh", "application/octet-stream"}, _
{"m3u", "audio/x-mpegurl"}, _
{"m4a", "audio/mp4a-latm"}, _
{"m4b", "audio/mp4a-latm"}, _
{"m4p", "audio/mp4a-latm"}, _
{"m4u", "video/vnd.mpegurl"}, _
{"m4v", "video/x-m4v"}, _
{"mac", "image/x-macpaint"}, _
{"man", "application/x-troff-man"}, _
{"mathml", "application/mathml+xml"}, _
{"me", "application/x-troff-me"}, _
{"mesh", "model/mesh"}, _
{"mid", "audio/midi"}, _
{"midi", "audio/midi"}, _
{"mif", "application/vnd.mif"}, _
{"mov", "video/quicktime"}, _
{"movie", "video/x-sgi-movie"}, _
{"mp2", "audio/mpeg"}, _
{"mp3", "audio/mpeg"}, _
{"mp4", "video/mp4"}, _
{"mpe", "video/mpeg"}, _
{"mpeg", "video/mpeg"}, _
{"mpg", "video/mpeg"}, _
{"mpga", "audio/mpeg"}, _
{"ms", "application/x-troff-ms"}, _
{"msh", "model/mesh"}, _
{"mxu", "video/vnd.mpegurl"}, _
{"nc", "application/x-netcdf"}, _
{"oda", "application/oda"}, _
{"ogg", "application/ogg"}, _
{"pbm", "image/x-portable-bitmap"}, _
{"pct", "image/pict"}, _
{"pdb", "chemical/x-pdb"}, _
{"pdf", "application/pdf"}, _
{"pgm", "image/x-portable-graymap"}, _
{"pgn", "application/x-chess-pgn"}, _
{"pic", "image/pict"}, _
{"pict", "image/pict"}, _
{"png", "image/png"}, _
{"pnm", "image/x-portable-anymap"}, _
{"pnt", "image/x-macpaint"}, _
{"pntg", "image/x-macpaint"}, _
{"ppm", "image/x-portable-pixmap"}, _
{"ppt", "application/vnd.ms-powerpoint"}, _
{"ps", "application/postscript"}, _
{"qt", "video/quicktime"}, _
{"qti", "image/x-quicktime"}, _
{"qtif", "image/x-quicktime"}, _
{"ra", "audio/x-pn-realaudio"}, _
{"ram", "audio/x-pn-realaudio"}, _
{"ras", "image/x-cmu-raster"}, _
{"rdf", "application/rdf+xml"}, _
{"rgb", "image/x-rgb"}, _
{"rm", "application/vnd.rn-realmedia"}, _
{"roff", "application/x-troff"}, _
{"rtf", "text/rtf"}, _
{"rtx", "text/richtext"}, _
{"sgm", "text/sgml"}, _
{"sgml", "text/sgml"}, _
{"sh", "application/x-sh"}, _
{"shar", "application/x-shar"}, _
{"silo", "model/mesh"}, _
{"sit", "application/x-stuffit"}, _
{"skd", "application/x-koan"}, _
{"skm", "application/x-koan"}, _
{"skp", "application/x-koan"}, _
{"skt", "application/x-koan"}, _
{"smi", "application/smil"}, _
{"smil", "application/smil"}, _
{"snd", "audio/basic"}, _
{"so", "application/octet-stream"}, _
{"spl", "application/x-futuresplash"}, _
{"src", "application/x-wais-source"}, _
{"sv4cpio", "application/x-sv4cpio"}, _
{"sv4crc", "application/x-sv4crc"}, _
{"svg", "image/svg+xml"}, _
{"swf", "application/x-shockwave-flash"}, _
{"t", "application/x-troff"}, _
{"tar", "application/x-tar"}, _
{"tcl", "application/x-tcl"}, _
{"tex", "application/x-tex"}, _
{"texi", "application/x-texinfo"}, _
{"texinfo", "application/x-texinfo"}, _
{"tif", "image/tiff"}, _
{"tiff", "image/tiff"}, _
{"tr", "application/x-troff"}, _
{"tsv", "text/tab-separated-values"}, _
{"txt", "text/plain"}, _
{"ustar", "application/x-ustar"}, _
{"vcd", "application/x-cdlink"}, _
{"vrml", "model/vrml"}, _
{"vxml", "application/voicexml+xml"}, _
{"wav", "audio/x-wav"}, _
{"wbmp", "image/vnd.wap.wbmp"}, _
{"wbmxl", "application/vnd.wap.wbxml"}, _
{"wml", "text/vnd.wap.wml"}, _
{"wmlc", "application/vnd.wap.wmlc"}, _
{"wmls", "text/vnd.wap.wmlscript"}, _
{"wmlsc", "application/vnd.wap.wmlscriptc"}, _
{"wrl", "model/vrml"}, _
{"xbm", "image/x-xbitmap"}, _
{"xht", "application/xhtml+xml"}, _
{"xhtml", "application/xhtml+xml"}, _
{"xls", "application/vnd.ms-excel"}, _
{"xml", "application/xml"}, _
{"xpm", "image/x-xpixmap"}, _
{"xsl", "application/xml"}, _
{"xslt", "application/xslt+xml"}, _
{"xul", "application/vnd.mozilla.xul+xml"}, _
{"xwd", "image/x-xwindowdump"}, _
{"xyz", "chemical/x-xyz"}, _
{"zip", "application/zip"} _
}
我发现运行这段代码有几个问题:
UInt32 mimetype;
FindMimeFromData(0, null, buffer, 256, null, 0, out mimetype, 0);
如果你尝试用x64/Win10运行它，你会得到
AccessViolationException "Attempted to read or write protected memory.
This is often an indication that other memory is corrupt"
多亏了这篇文章，PtrToStringUni在windows 10和@xanatos中无法工作
我修改了我的解决方案，在x64和。net Core 2.1下运行:
[DllImport("urlmon.dll", CharSet = CharSet.Unicode, ExactSpelling = true,
SetLastError = false)]
static extern int FindMimeFromData(IntPtr pBC,
[MarshalAs(UnmanagedType.LPWStr)] string pwzUrl,
[MarshalAs(UnmanagedType.LPArray, ArraySubType=UnmanagedType.I1,
SizeParamIndex=3)]
byte[] pBuffer,
int cbSize,
[MarshalAs(UnmanagedType.LPWStr)] string pwzMimeProposed,
int dwMimeFlags,
out IntPtr ppwzMimeOut,
int dwReserved);
string getMimeFromFile(byte[] fileSource)
{
byte[] buffer = new byte[256];
using (Stream stream = new MemoryStream(fileSource))
{
if (stream.Length >= 256)
stream.Read(buffer, 0, 256);
else
stream.Read(buffer, 0, (int)stream.Length);
}
try
{
IntPtr mimeTypePtr;
FindMimeFromData(IntPtr.Zero, null, buffer, buffer.Length,
null, 0, out mimeTypePtr, 0);
string mime = Marshal.PtrToStringUni(mimeTypePtr);
Marshal.FreeCoTaskMem(mimeTypePtr);
return mime;
}
catch (Exception ex)
{
return "unknown/unknown";
}
}
谢谢
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