第一个种方式利用Win32API 读取文件头获取Mime-Type

[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

);

public

string

getMimeFromFile(

string

filename)

{

if

(

!

File.Exists(filename))

throw

new

FileNotFoundException(filename

+

"

not found

"

);

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);

return

mime;

}

catch

(Exception e)

{

return

"

unknown/unknown

"

;

}

}

第二种方式 利用系统注册表查找Mime-Type

using

System.IO;

using

Microsoft.Win32;

string

GetMimeType(FileInfo fileInfo)

{

string

mimeType

=

"

application/unknown

"

;

RegistryKey regKey

=

Registry.ClassesRoot.OpenSubKey(

fileInfo.Extension.ToLower()

);

if

(regKey

!=

null

)

{

object

contentType

=

regKey.GetValue(

"

Content Type

"

);

if

(contentType

!=

null

)

mimeType

=

contentType.ToString();

}

return

mimeType;

}