使用Shell32获取文件扩展属性时出现异常

Question

我正在尝试使用Shell32来获取c#中的扩展文件属性。

我的代码如下所示。

        var file = FileUpload1.PostedFile;

        List<string> arrHeaders = new List<string>();

        Shell shell = new ShellClass();

        //Exception is thrown at next line
        Folder rFolder = shell.NameSpace(Path.GetDirectoryName(file.FileName));
        FolderItem rFiles = rFolder.ParseName(Path.GetFileName(file.FileName));

        for (int i = 0; i < short.MaxValue; i++)
        {
            string value = rFolder.GetDetailsOf(rFiles, i).Trim();
            arrHeaders.Add(value);
        }

我得到的异常如下。

​

消息-无法将类型为'Shell32.ShellClass‘的COM对象强制转换为接口类型'Shell32.IShellDispatch6’。此操作失败，原因是由于以下错误，对COM组件的QueryInterface调用失败:不支持此类接口(来自HRESULT的异常: 0x80004002 (E_NOINTERFACE))。

堆栈跟踪-在System.StubHelpers.StubHelpers.GetCOMIPFromRCW(Object objSrc，IntPtr pCPCMD，IntPtr& ppTarget，Boolean& pfNeedsRelease)在Shell32.ShellClass.NameSpace(Object vDir)在PBSWebApplication.Test.Button1_OnClick(Object sender，e)在System.Web.UI.WebControls.Button.OnClick(EventArgs e)在System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument)在System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument)在System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl，字符串eventArgument) at System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint，Boolean includeStagesAfterAsyncPoint)

如何解决这个问题？

谢谢。

Answer 1

正如您所确定的，这是因为Shell32需要STA线程。如果你不能像在你的解决方案中那样简单地配置你的应用程序使用STA线程运行，那么作为替代方案，你可以创建一个单独的STA线程，使用它来运行Shell32代码，然后继续执行。例如，this是我在编写SSIS脚本任务时得到的结果，据我所知，它总是在MTA线程上运行。在我的例子中，我调用了一个不同的Shell32方法(CopyHere)，但同样的逻辑也适用于您想调用的任何方法：

    /// <summary>
    /// Ugh! SSIS runs script tasks on MTA threads but Shell32 only wants to 
    /// run on STA thread. So start a new STA thread to call UnZip, block 
    /// till it's done, then return. 
    /// We use Shell32 since .net 2 doesn't have ZipFile and we prefer not to 
    /// ship other dlls as they normally need to be deployed to the GAC. So this 
    /// is easiest, although not very pretty.
    /// </summary>
    /// <param name="zipFile">File to unzip</param>
    /// <param name="folderPath">Folder to put the unzipped files</param>
    public static void UnZipFromMTAThread(string zipFile, string folderPath)
    {
        object[] args = new object[] { zipFile, folderPath };
        if (Thread.CurrentThread.GetApartmentState() == ApartmentState.STA)
        {
            UnZip(args);
        }
        else
        {
            Thread staThread = new Thread(new ParameterizedThreadStart(UnZip));
            staThread.SetApartmentState(ApartmentState.STA);
            staThread.Start(args);
            staThread.Join();
        }
    }

    /// <summary>
    /// From http://www.fluxbytes.com/csharp/unzipping-files-using-shell32-in-c/ but with 
    /// args packed in object array so can be called from new STA Thread in UnZipFromMTAThread().
    /// </summary>
    /// <param name="param">object array containing: [string zipFile, string destinationFolderPath]</param>
    private static void UnZip(object param)
    {
        object[] args = (object[]) param;
        string zipFile = (string)args[0];
        string folderPath = (string)args[1];


        if (!File.Exists(zipFile))
            throw new FileNotFoundException();

        if (!Directory.Exists(folderPath))
            Directory.CreateDirectory(folderPath);

        Shell32.Shell objShell = new Shell32.Shell();
        Shell32.Folder destinationFolder = objShell.NameSpace(folderPath);
        Shell32.Folder sourceFile = objShell.NameSpace(zipFile);

        foreach (var file in sourceFile.Items())
        {
            // Flags are: No progress displayed, Respond with 'Yes to All' for any dialog, no UI on error
            // I added 1024 although not sure it's relevant with Zip files. 
            // See https://msdn.microsoft.com/en-us/library/windows/desktop/bb787866%28v=vs.85%29.aspx?f=255&MSPPError=-2147217396
            destinationFolder.CopyHere(file, 4 | 16 | 1024); 
        }
    }

Answer 2

事实证明，向我的类添加STAThread属性是一个简单的解决方案，这个问题神奇地消失了。

这是我更新后的完整代码。

注意:这是一个简单的控制台应用程序。

class Program
{
    [STAThread]
    static void Main(string[] args)
    {
        Console.Title = "Extended file properties.";

        List<string> arrHeaders = new List<string>();

        Shell32.Shell shell = new Shell32.Shell();
        Shell32.Folder objFolder;

        objFolder = shell.NameSpace(@"C:\Users\Admin\Pictures\PBS Docs");

        for (int i = 0; i < short.MaxValue; i++)
        {
            string header = objFolder.GetDetailsOf(null, i);
            if (String.IsNullOrEmpty(header))
                break;
            arrHeaders.Add(header);
        }

        foreach (Shell32.FolderItem2 item in objFolder.Items())
        {
            for (int i = 0; i < arrHeaders.Count; i++)
            {
                Console.WriteLine("{0}\t{1}: {2}", i, arrHeaders[i], objFolder.GetDetailsOf(item, i));
            }
        }
     }
}

Answer 3

我有类似的问题，jeronevw在这个论坛上的回答为我解决了这个问题：https://social.msdn.microsoft.com/Forums/vstudio/en-US/b25e2b8f-141a-4a1c-a73c-1cb92f953b2b/instantiate-shell32shell-object-in-windows-8?forum=clr

public Shell32.Folder GetShell32NameSpaceFolder(Object folder)
{
  Type shellAppType = Type.GetTypeFromProgID("Shell.Application");

  Object shell = Activator.CreateInstance(shellAppType);
  return (Shell32.Folder)shellAppType.InvokeMember("NameSpace",
System.Reflection.BindingFlags.InvokeMethod, null, shell, new object[] { folder });
}

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