4-4-2011 16:27:14
tạo file default.aspx rồi cho cái này vào

<asp:FileUpload ID="file" runat="server" />
<asp:Button ID="btnRun" runat="server" Text="Run" OnClick="btnRun_Click" />
<h1>
<asp:Label ID="lbl" runat="server"></asp:Label>
</h1>

trong code viết như sau

if (file.PostedFile.FileName != "")
{
string fname = Guid.NewGuid().ToString("N");
string f_path = Server.MapPath("/" + fname);
file.PostedFile.SaveAs(f_path);
string mt = Engine.getMimeFromFile(f_path, file.PostedFile.ContentLength, fname);
lbl.Text = mt;
}

và cái file engine

[code]
public class Engine
{

[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);

public static string getMimeFromFile(string path, int contentLength, string fname)
{
IntPtr mimeout;

int MaxContent = contentLength;
if (MaxContent > 4096) MaxContent = 4096;

byte[] buf = new byte[MaxContent];

FileStream fs = new FileStream(path, FileMode.Open);
fs.Read(buf, 0, MaxContent);
fs.Close();
int result = FindMimeFromData(IntPtr.Zero, fname, buf, MaxContent, null, 0, out mimeout, 0);

if (result != 0)
{
Marshal.FreeCoTaskMem(mimeout);
return "";
}

string mime = Marshal.PtrToStringUni(mimeout);
Marshal.FreeCoTaskMem(mimeout);

return mime.ToLower();
}
}
[code]

có dùng

using System.Runtime.InteropServices;

là ok
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