C# .NET Core 3.0 选择文件夹对话框

• 下载源代码文件 - 5.2 MB

引言

对于需要从 .NET Framework 迁移到 .NET Core 的现代桌面 Windows Forms 应用程序，本文讨论了 Windows Forms 的一个组件的实现，即文件夹对话框。该组件允许用户以打开文件对话框的现代外观和感觉干净地选择文件夹目标。它也与 .NET Framework 兼容。

背景

此演示将包括运行一个控制台应用程序，启动一个打开文件夹对话框，允许用户选择一个文件夹，然后在控制台窗口中显示文件夹路径。我将其放在控制台应用程序中是为了演示易于实现。

Using the Code

此代码示例采用分层方法。第一层是程序集层。为了使您的业务逻辑层 (BLL) 和控制台层引用这些 Microsoft .NET Core DLL 是必要的。开发模式背后的思想是允许控制台演示文件夹对话框，并且 BLL 层可以被重用于任何其他项目。

程序集层

包含以下 DLL

• System.Drawing.Dll
• System.Windows.Forms.dll

** 这些 DLL 可以在您系统的以下位置找到：C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App\3.0.0 **

业务层

一个 .NET Core 类库，包含一个类和一个接口文件，Select.cs 和 ISelect.cs。

Select.cs

using System;
using System.IO;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using System.Windows.Forms;

namespace FolderDialog.Bll.FolderDialog
{
    public class Select : ISelect
    {
        /// <summary>
        /// Gets/sets folder in which dialog will be open.
        /// </summary>
        public string InitialFolder { get; set; }

        /// <summary>
        /// Gets/sets directory in which dialog will be open 
        /// if there is no recent directory available.
        /// </summary>
        public string DefaultFolder { get; set; }

        /// <summary>
        /// Gets selected folder.
        /// </summary>
        public string Folder { get; set; }
        public DialogResult ShowDialog()
        {
            return ShowDialog(owner: new WindowWrapper(IntPtr.Zero));
        }
        public DialogResult ShowDialog(IWin32Window owner)
        {
            if (Environment.OSVersion.Version.Major >= 6)
            {
                return ShowVistaDialog(owner);
            }
            else
            {
                return ShowLegacyDialog(owner);
            }
        }
        public DialogResult ShowVistaDialog(IWin32Window owner)
        {
            var frm = (NativeMethods.IFileDialog)(new NativeMethods.FileOpenDialogRCW());
            uint options;
            frm.GetOptions(out options);
            options |= NativeMethods.FOS_PICKFOLDERS | 
                       NativeMethods.FOS_FORCEFILESYSTEM | 
                       NativeMethods.FOS_NOVALIDATE | 
                       NativeMethods.FOS_NOTESTFILECREATE | 
                       NativeMethods.FOS_DONTADDTORECENT;
            frm.SetOptions(options);
            if (this.InitialFolder != null)
            {
                NativeMethods.IShellItem directoryShellItem;
                var riid = new Guid("43826D1E-E718-42EE-BC55-A1E261C37BFE"); //IShellItem
                if (NativeMethods.SHCreateItemFromParsingName
                   (this.InitialFolder, IntPtr.Zero, ref riid, 
                    out directoryShellItem) == NativeMethods.S_OK)
                {
                    frm.SetFolder(directoryShellItem);
                }
            }
            if (this.DefaultFolder != null)
            {
                NativeMethods.IShellItem directoryShellItem;
                var riid = new Guid("43826D1E-E718-42EE-BC55-A1E261C37BFE"); //IShellItem
                if (NativeMethods.SHCreateItemFromParsingName
                   (this.DefaultFolder, IntPtr.Zero, ref riid, 
                    out directoryShellItem) == NativeMethods.S_OK)
                {
                    frm.SetDefaultFolder(directoryShellItem);
                }
            }

            if (frm.Show(owner.Handle) == NativeMethods.S_OK)
            {
                NativeMethods.IShellItem shellItem;
                if (frm.GetResult(out shellItem) == NativeMethods.S_OK)
                {
                    IntPtr pszString;
                    if (shellItem.GetDisplayName(NativeMethods.SIGDN_FILESYSPATH, 
                        out pszString) == NativeMethods.S_OK)
                    {
                        if (pszString != IntPtr.Zero)
                        {
                            try
                            {
                                this.Folder = Marshal.PtrToStringAuto(pszString);
                                return DialogResult.OK;
                            }
                            finally
                            {
                                Marshal.FreeCoTaskMem(pszString);
                            }
                        }
                    }
                }
            }
            return DialogResult.Cancel;
        }
        public DialogResult ShowLegacyDialog(IWin32Window owner)
        {
            using (var frm = new SaveFileDialog())
            {
                frm.CheckFileExists = false;
                frm.CheckPathExists = true;
                frm.CreatePrompt = false;
                frm.Filter = "|" + Guid.Empty.ToString();
                frm.FileName = "any";
                if (this.InitialFolder != null) { frm.InitialDirectory = this.InitialFolder; }
                frm.OverwritePrompt = false;
                frm.Title = "Select Folder";
                frm.ValidateNames = false;
                if (frm.ShowDialog(owner) == DialogResult.OK)
                {
                    this.Folder = Path.GetDirectoryName(frm.FileName);
                    return DialogResult.OK;
                }
                else
                {
                    return DialogResult.Cancel;
                }
            }
        }
        public void Dispose() { } //just to have possibility of Using statement.
    }
    public class WindowWrapper : System.Windows.Forms.IWin32Window
    {
        /// <summary>
        /// Constructor
        /// </summary>
        /// <param name="handle">Handle to wrap</param>
        public WindowWrapper(IntPtr handle)
        {
            _hwnd = handle;
        }

        /// <summary>
        /// Original ptr
        /// </summary>
        public IntPtr Handle
        {
            get { return _hwnd; }
        }

        private IntPtr _hwnd;
    }
    internal static class NativeMethods
    {
        #region Constants

        public const uint FOS_PICKFOLDERS = 0x00000020;
        public const uint FOS_FORCEFILESYSTEM = 0x00000040;
        public const uint FOS_NOVALIDATE = 0x00000100;
        public const uint FOS_NOTESTFILECREATE = 0x00010000;
        public const uint FOS_DONTADDTORECENT = 0x02000000;

        public const uint S_OK = 0x0000;

        public const uint SIGDN_FILESYSPATH = 0x80058000;

        #endregion

        #region COM

        [ComImport, ClassInterface(ClassInterfaceType.None), 
        TypeLibType(TypeLibTypeFlags.FCanCreate), 
                    Guid("DC1C5A9C-E88A-4DDE-A5A1-60F82A20AEF7")]
        internal class FileOpenDialogRCW { }

        [ComImport(), Guid("42F85136-DB7E-439C-85F1-E4075D135FC8"), 
                      InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
        internal interface IFileDialog
        {
            [MethodImpl(MethodImplOptions.InternalCall, 
             MethodCodeType = MethodCodeType.Runtime)]
            [PreserveSig()]
            uint Show([In, Optional] IntPtr hwndOwner); //IModalWindow 

            [MethodImpl(MethodImplOptions.InternalCall, 
             MethodCodeType = MethodCodeType.Runtime)]
            uint SetFileTypes([In] uint cFileTypes, 
            [In, MarshalAs(UnmanagedType.LPArray)] IntPtr rgFilterSpec);

            [MethodImpl(MethodImplOptions.InternalCall, 
             MethodCodeType = MethodCodeType.Runtime)]
            uint SetFileTypeIndex([In] uint iFileType);

            [MethodImpl(MethodImplOptions.InternalCall, 
             MethodCodeType = MethodCodeType.Runtime)]
            uint GetFileTypeIndex(out uint piFileType);

            [MethodImpl(MethodImplOptions.InternalCall, 
             MethodCodeType = MethodCodeType.Runtime)]
            uint Advise([In, MarshalAs(UnmanagedType.Interface)] IntPtr pfde, 
            out uint pdwCookie);

            [MethodImpl(MethodImplOptions.InternalCall, 
             MethodCodeType = MethodCodeType.Runtime)]
            uint Unadvise([In] uint dwCookie);

            [MethodImpl(MethodImplOptions.InternalCall, 
             MethodCodeType = MethodCodeType.Runtime)]
            uint SetOptions([In] uint fos);

            [MethodImpl(MethodImplOptions.InternalCall, 
             MethodCodeType = MethodCodeType.Runtime)]
            uint GetOptions(out uint fos);

            [MethodImpl(MethodImplOptions.InternalCall, 
             MethodCodeType = MethodCodeType.Runtime)]
            void SetDefaultFolder([In, MarshalAs(UnmanagedType.Interface)] IShellItem psi);

            [MethodImpl(MethodImplOptions.InternalCall, 
             MethodCodeType = MethodCodeType.Runtime)]
            uint SetFolder([In, MarshalAs(UnmanagedType.Interface)] IShellItem psi);

            [MethodImpl(MethodImplOptions.InternalCall, 
             MethodCodeType = MethodCodeType.Runtime)]
            uint GetFolder([MarshalAs(UnmanagedType.Interface)] out IShellItem ppsi);

            [MethodImpl(MethodImplOptions.InternalCall, 
             MethodCodeType = MethodCodeType.Runtime)]
            uint GetCurrentSelection
                 ([MarshalAs(UnmanagedType.Interface)] out IShellItem ppsi);

            [MethodImpl(MethodImplOptions.InternalCall, 
             MethodCodeType = MethodCodeType.Runtime)]
            uint SetFileName([In, MarshalAs(UnmanagedType.LPWStr)] string pszName);

            [MethodImpl(MethodImplOptions.InternalCall, 
             MethodCodeType = MethodCodeType.Runtime)]
            uint GetFileName([MarshalAs(UnmanagedType.LPWStr)] out string pszName);

            [MethodImpl(MethodImplOptions.InternalCall, 
             MethodCodeType = MethodCodeType.Runtime)]
            uint SetTitle([In, MarshalAs(UnmanagedType.LPWStr)] string pszTitle);

            [MethodImpl(MethodImplOptions.InternalCall, 
             MethodCodeType = MethodCodeType.Runtime)]
            uint SetOkButtonLabel([In, MarshalAs(UnmanagedType.LPWStr)] string pszText);

            [MethodImpl(MethodImplOptions.InternalCall, 
             MethodCodeType = MethodCodeType.Runtime)]
            uint SetFileNameLabel([In, MarshalAs(UnmanagedType.LPWStr)] string pszLabel);

            [MethodImpl(MethodImplOptions.InternalCall, 
             MethodCodeType = MethodCodeType.Runtime)]
            uint GetResult([MarshalAs(UnmanagedType.Interface)] out IShellItem ppsi);

            [MethodImpl(MethodImplOptions.InternalCall, 
             MethodCodeType = MethodCodeType.Runtime)]
            uint AddPlace
              ([In, MarshalAs(UnmanagedType.Interface)] IShellItem psi, uint fdap);

            [MethodImpl(MethodImplOptions.InternalCall, 
             MethodCodeType = MethodCodeType.Runtime)]
            uint SetDefaultExtension([In, MarshalAs(UnmanagedType.LPWStr)] 
                                     string pszDefaultExtension);

            [MethodImpl(MethodImplOptions.InternalCall, 
                        MethodCodeType = MethodCodeType.Runtime)]
            uint Close([MarshalAs(UnmanagedType.Error)] uint hr);

            [MethodImpl(MethodImplOptions.InternalCall, 
                        MethodCodeType = MethodCodeType.Runtime)]
            uint SetClientGuid([In] ref Guid guid);

            [MethodImpl(MethodImplOptions.InternalCall, 
                        MethodCodeType = MethodCodeType.Runtime)]
            uint ClearClientData();

            [MethodImpl(MethodImplOptions.InternalCall, 
                        MethodCodeType = MethodCodeType.Runtime)]
            uint SetFilter([MarshalAs(UnmanagedType.Interface)] IntPtr pFilter);
        }

        [ComImport, Guid("43826D1E-E718-42EE-BC55-A1E261C37BFE"), 
                    InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
        internal interface IShellItem
        {
            [MethodImpl(MethodImplOptions.InternalCall, 
                        MethodCodeType = MethodCodeType.Runtime)]
            uint BindToHandler([In] IntPtr pbc, [In] ref Guid rbhid, 
            [In] ref Guid riid, [Out, MarshalAs(UnmanagedType.Interface)] out IntPtr ppvOut);

            [MethodImpl(MethodImplOptions.InternalCall, 
                        MethodCodeType = MethodCodeType.Runtime)]
            uint GetParent([MarshalAs(UnmanagedType.Interface)] out IShellItem ppsi);

            [MethodImpl(MethodImplOptions.InternalCall, 
                        MethodCodeType = MethodCodeType.Runtime)]
            uint GetDisplayName([In] uint sigdnName, out IntPtr ppszName);

            [MethodImpl(MethodImplOptions.InternalCall, 
                        MethodCodeType = MethodCodeType.Runtime)]
            uint GetAttributes([In] uint sfgaoMask, out uint psfgaoAttribs);

            [MethodImpl(MethodImplOptions.InternalCall, 
                        MethodCodeType = MethodCodeType.Runtime)]
            uint Compare([In, MarshalAs(UnmanagedType.Interface)] IShellItem psi, 
                         [In] uint hint, out int piOrder);
        }

        #endregion

        [DllImport("shell32.dll", CharSet = CharSet.Unicode, SetLastError = true)]
        internal static extern int SHCreateItemFromParsingName
         ([MarshalAs(UnmanagedType.LPWStr)] string pszPath, IntPtr pbc, 
         ref Guid riid, [MarshalAs(UnmanagedType.Interface)] out IShellItem ppv);
    }
}

ISelect.cs

using System.Windows.Forms;

namespace FolderDialog.Bll.FolderDialog
{
    public interface ISelect
    {
        string InitialFolder { get; set; }
        string DefaultFolder { get; set; }
        string Folder { get; set; }
        DialogResult ShowDialog();
        DialogResult ShowDialog(IWin32Window owner);
        DialogResult ShowVistaDialog(IWin32Window owner);
        DialogResult ShowLegacyDialog(IWin32Window owner);
        void Dispose();
    }
}

控制台层

一个 .NET Core 3.0 控制台应用程序。

using System;

namespace FolderDialog.Console
{    
    class Program
    {        
        [STAThread]
        static void Main(string[] args)
        {
            System.Console.WriteLine(": : : : : Folder Dialog App : : : : :");
            Bll.FolderDialog.ISelect select = new Bll.FolderDialog.Select();
            select.InitialFolder = "C:\\";
            select.ShowDialog();
            System.Console.WriteLine($"Folder Selected: {select.Folder}");
            System.Console.WriteLine("Press any key to continue...");
            System.Console.ReadLine();
        }
    }
}

关注点

此代码使用 COM 引用与 Windows 对话框交互。然后，它在 Select.cs 文件中使用一个 WindowWrapper 类来实例化 ShowDialog IWin32Window 值。

上述代码片段在 .NET Framework 和 .NET Core 中都可以工作。

另一个令人兴奋的信息。此代码是大约 10 年前从资源中合并的两个项目的成果。原始资源是

• https://code.google.com/archive/p/fed/
• https://www.medo64.com/2011/12/openfolderdialog/

历史

• 2019年1月6日 19:44 EST - 初始发布