这是极端的，但是我使用名为FILE_TYPES的2列数据库表构建了一个动态的、数据库驱动的过滤器，字段名为EXTENSION和DOCTYPE:

---------------------------------
| EXTENSION  |  DOCTYPE         |
---------------------------------
|   .doc     |  Document        |
|   .docx    |  Document        |
|   .pdf     |  Document        |
|   ...      |  ...             |
|   .bmp     |  Image           |
|   .jpg     |  Image           |
|   ...      |  ...             |
---------------------------------

显然，我有许多不同的类型和扩展，但在本例中我将其简化。这是我的函数:

    private static string GetUploadFilter()
    {
        // Desired format:
        // "Document files (*.doc, *.docx, *.pdf)|*.doc;*.docx;*.pdf|"
        // "Image files (*.bmp, *.jpg)|*.bmp;*.jpg|"

        string filter = String.Empty;
        string nameFilter = String.Empty;
        string extFilter = String.Empty;

        // Used to get extensions
        DataTable dt = new DataTable();
        dt = DataLayer.Get_DataTable("SELECT * FROM FILE_TYPES ORDER BY EXTENSION");

        // Used to cycle through doctype groupings ("Images", "Documents", etc.)
        DataTable dtDocTypes = new DataTable();
        dtDocTypes = DataLayer.Get_DataTable("SELECT DISTINCT DOCTYPE FROM FILE_TYPES ORDER BY DOCTYPE");

        // For each doctype grouping...
        foreach (DataRow drDocType in dtDocTypes.Rows)
        {
            nameFilter = drDocType["DOCTYPE"].ToString() + " files (";

            // ... add its associated extensions
            foreach (DataRow dr in dt.Rows)
            {
                if (dr["DOCTYPE"].ToString() == drDocType["DOCTYPE"].ToString())
                {
                    nameFilter += "*" + dr["EXTENSION"].ToString() + ", ";
                    extFilter += "*" + dr["EXTENSION"].ToString() + ";";
                }                    
            }

            // Remove endings put in place in case there was another to add, and end them with pipe characters:
            nameFilter = nameFilter.TrimEnd(' ').TrimEnd(',');
            nameFilter += ")|";
            extFilter = extFilter.TrimEnd(';');
            extFilter += "|";

            // Add the name and its extensions to our main filter
            filter += nameFilter + extFilter;

            extFilter = ""; // clear it for next round; nameFilter will be reset to the next DOCTYPE on next pass
        }

        filter = filter.TrimEnd('|');
        return filter;
    }

    private void UploadFile(string fileType, object sender)
    {            
        Microsoft.Win32.OpenFileDialog dlg = new Microsoft.Win32.OpenFileDialog();
        string filter = GetUploadFilter();
        dlg.Filter = filter;

        if (dlg.ShowDialog().Value == true)
        {
            string fileName = dlg.FileName;

            System.IO.FileStream fs = System.IO.File.OpenRead(fileName);
            byte[] array = new byte[fs.Length];

            // This will give you just the filename
            fileName = fileName.Split('\\')[fileName.Split('\\').Length - 1];
            ...

应该生成如下所示的过滤器:

完整的c#解决方案在这里:

private void btnSelectImage_Click(object sender, RoutedEventArgs e)
{
    // Configure open file dialog box 
    Microsoft.Win32.OpenFileDialog dlg = new Microsoft.Win32.OpenFileDialog();
    dlg.Filter = "";

    ImageCodecInfo[] codecs = ImageCodecInfo.GetImageEncoders();
    string sep = string.Empty;

    foreach (var c in codecs)
    {
       string codecName = c.CodecName.Substring(8).Replace("Codec", "Files").Trim();
       dlg.Filter = String.Format("{0}{1}{2} ({3})|{3}", dlg.Filter, sep, codecName, c.FilenameExtension);
       sep = "|";
    }

    dlg.Filter = String.Format("{0}{1}{2} ({3})|{3}", dlg.Filter, sep, "All Files", "*.*"); 

    dlg.DefaultExt = ".png"; // Default file extension 

    // Show open file dialog box 
    Nullable<bool> result = dlg.ShowDialog();

    // Process open file dialog box results 
    if (result == true)
    {
       // Open document 
       string fileName  = dlg.FileName;
       // Do something with fileName  
    }
} 

写出应用程序需要的类型。(ref FileDialog.Filter)。以下是最常见的图像格式。

private static string GetImageFilter()
{
    return
        "All Files (*.*)|*.*" +
        "|All Pictures (*.emf;*.wmf;*.jpg;*.jpeg;*.jfif;*.jpe;*.png;*.bmp;*.dib;*.rle;*.gif;*.emz;*.wmz;*.tif;*.tiff;*.svg;*.ico)" +
            "|*.emf;*.wmf;*.jpg;*.jpeg;*.jfif;*.jpe;*.png;*.bmp;*.dib;*.rle;*.gif;*.emz;*.wmz;*.tif;*.tiff;*.svg;*.ico" +
        "|Windows Enhanced Metafile (*.emf)|*.emf" +
        "|Windows Metafile (*.wmf)|*.wmf" +
        "|JPEG File Interchange Format (*.jpg;*.jpeg;*.jfif;*.jpe)|*.jpg;*.jpeg;*.jfif;*.jpe" +
        "|Portable Network Graphics (*.png)|*.png" +
        "|Bitmap Image File (*.bmp;*.dib;*.rle)|*.bmp;*.dib;*.rle" +
        "|Compressed Windows Enhanced Metafile (*.emz)|*.emz" +
        "|Compressed Windows MetaFile (*.wmz)|*.wmz" +
        "|Tag Image File Format (*.tif;*.tiff)|*.tif;*.tiff" +
        "|Scalable Vector Graphics (*.svg)|*.svg" +
        "|Icon (*.ico)|*.ico";
}

示例使用

设置FilterIndex = 2以预选“所有图片”。不要设置openFileDialog。除非你有一个很好的理由。

void OpenImageFile()
{
    var openFileDialog  = new OpenFileDialog
    {
        Filter = GetImageFilter(),
        FilterIndex = 2,
        RestoreDirectory = true
    };
    DialogResult result = openFileDialog.ShowDialog();

    // do something with your file
    // bool resultOk = (result == System.Windows.Forms.DialogResult.OK);
    // string filePath = openFileDialog.FileName;
    // ...
}

下面是一个ImageCodecInfo建议的例子(在VB中):

   Imports System.Drawing.Imaging
        ...            

        Dim ofd as new OpenFileDialog()
        ofd.Filter = ""
        Dim codecs As ImageCodecInfo() = ImageCodecInfo.GetImageEncoders()
        Dim sep As String = String.Empty
        For Each c As ImageCodecInfo In codecs
            Dim codecName As String = c.CodecName.Substring(8).Replace("Codec", "Files").Trim()
            ofd.Filter = String.Format("{0}{1}{2} ({3})|{3}", ofd.Filter, sep, codecName, c.FilenameExtension)
            sep = "|"
        Next
        ofd.Filter = String.Format("{0}{1}{2} ({3})|{3}", ofd.Filter, sep, "All Files", "*.*")

它是这样的:

使用此方法返回一个与Filter兼容的字符串，该字符串由支持当前系统理解的图像格式的ImageCodecInfo构建。

        /// <summary>
        /// Get the Filter string for all supported image types.
        /// To be used in the FileDialog class Filter Property.
        /// </summary>
        /// <returns></returns>
        public static string GetImageFilter()
        {
            string imageExtensions = string.Empty;
            string separator = "";
            ImageCodecInfo[] codecs = ImageCodecInfo.GetImageEncoders();
            Dictionary<string, string> imageFilters = new Dictionary<string, string>();
            foreach (ImageCodecInfo codec in codecs)
            {
                imageExtensions = $"{imageExtensions}{separator}{codec.FilenameExtension.ToLower()}";
                separator = ";";
                imageFilters.Add($"{codec.FormatDescription} files ({codec.FilenameExtension.ToLower()})", codec.FilenameExtension.ToLower());
            }
            string result = string.Empty;
            separator = "";
            foreach (KeyValuePair<string, string> filter in imageFilters)
            {
                result += $"{separator}{filter.Key}|{filter.Value}";
                separator = "|";
            }
            if (!string.IsNullOrEmpty(imageExtensions))
            {
                result += $"{separator}Image files|{imageExtensions}";
            }
            return result;
        }

结果如下所示:

为了匹配一个由不同类别的文件组成的列表，你可以像这样使用过滤器:

        var dlg = new Microsoft.Win32.OpenFileDialog()
        {
            DefaultExt = ".xlsx",
            Filter = "Excel Files (*.xls, *.xlsx)|*.xls;*.xlsx|CSV Files (*.csv)|*.csv"
        };