設置文件內容類型，在silverlight中SaveFileDialog

Question

正如標題所說;有沒有什麼方法可以在Silverlight的SaveFileDialog中設置文件的內容類型？我沒有找到辦法，如果不可能，我不會感到驚訝，只是想我問，看看有沒有人知道。

Answer 1

this.dialog = new SaveFileDialog(); 

      try 
      { 
       this.dialog.DefaultExt = ".txt"; 
       this.dialog.Filter = "Text Files|*.txt|Log Files|*.log|All Files|*.*"; 
       this.dialog.FilterIndex = 2; 
      } 
      catch (Exception ex) 
      { 
       this.tblError.Text = "Error configuring SaveFileDialog: " + ex.Message; 
      } 

Answer 2

你在找什麼是上傳文件的MIME類型。我認爲這將在Silverlight中工作，我不明白爲什麼不，但我從來沒有在這方面使用它。您需要添加以下內容：

using System.Reflection; 
using System.Runtime.InteropServices; 

[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 
); 

public void SomeMethod(string fileName) 
{ 
    string mimeType = getMimeFromFile(fileName); 

    if (mimeType == "text/plain") 
{ 
     // do something 
} 
} 

private 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 ex) 
     { 
      return ex.Message; 
     } 
    }