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Windows Shell 编程，即 Windows 外壳编程。我们所看到的资源管理器以及整个桌面，都是一个 Shell。

我们知道，在win32中是以外壳名字空间的形式来组织文件系统的，在外壳名字空间里的每一个对象(注)都实现了一个IShellFolder的接口，通过这个接口我们可以直接查询或间接得到其他相关的接口。

下面做个程序用于浏览文件夹：

在C#中，我们这样定义 IShellFolder 接口：

代码

    [ComImport]
    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    [Guid("000214E6-0000-0000-C000-000000000046")]
    public interface IShellFolder {
        void ParseDisplayName(
            IntPtr hwnd,
            IntPtr pbc,
            [MarshalAs(UnmanagedType.LPWStr)] string pszDisplayName,
            out uint pchEaten,
            out IntPtr ppidl,
            ref uint pdwAttributes);
        [PreserveSig]
int EnumObjects(IntPtr hWnd, SHCONTF flags, out IntPtr enumIDList);void BindToObject(
            IntPtr pidl,
            IntPtr pbc,
            [In()] ref Guid riid,
            out IShellFolder ppv);void BindToStorage(
            IntPtr pidl,
            IntPtr pbc,
            [In()] ref Guid riid,
            [MarshalAs(UnmanagedType.Interface)] out object ppv);
        [PreserveSig()]uint CompareIDs(
            int lParam,
            IntPtr pidl1,
            IntPtr pidl2);void CreateViewObject(
            IntPtr hwndOwner,
            [In()] ref Guid riid,
            [MarshalAs(UnmanagedType.Interface)] out object ppv);void GetAttributesOf(
            uint cidl,
            [In(), MarshalAs(UnmanagedType.LPArray)] IntPtr[] apidl,
           ref SFGAO rgfInOut);
        IntPtr GetUIObjectOf(
            IntPtr hwndOwner,
            uint cidl,
            [MarshalAs(UnmanagedType.LPArray)] IntPtr[] apidl,
            [In()] ref Guid riid,
            out IntPtr rgfReserved);void GetDisplayNameOf(
            IntPtr pidl,
            SHGNO uFlags,
            IntPtr lpName);
        IntPtr SetNameOf(
            IntPtr hwnd,
            IntPtr pidl,
            [MarshalAs(UnmanagedType.LPWStr)] string pszName,
           SHGNO uFlags);
    }

桌面是最顶级的文件夹，外壳名字空间中其他各项都可以用从桌面开始的 PIDL 加以表示。

 可以通过 API  SHGetDesktopFolder获取“桌面”的 PIDL 和其 IShellFolder 接口：

代码

        public static IShellFolder GetDesktopFolder(out IntPtr ppshf)  {
            SHGetDesktopFolder(out ppshf);
            Object obj = Marshal.GetObjectForIUnknown(ppshf);
            return (IShellFolder)obj;
        }

下面是程序调用的代码：

代码

        private void Form1_Load(object sender, EventArgs e){//获得桌面 PIDL
            IntPtr desktopPtr;
            IShellFolder desktop = API.GetDesktopFolder(out desktopPtr);//获取 C 盘的 PIDL
            string FolderPath = @"C:\";
            IntPtr Pidl = IntPtr.Zero;
            IShellFolder Root;
            uint i, j = 0;
            desktop.ParseDisplayName(Handle, IntPtr.Zero, FolderPath, out i, out Pidl, ref j);
            desktop.BindToObject(Pidl, IntPtr.Zero, ref Guids.IID_IShellFolder, out Root);
            Marshal.ReleaseComObject(desktop);//循环查找 C 盘下面的文件/文件夹的 PIDL
            IEnumIDList fileEnum = null;
            IEnumIDList folderEnum = null;
            IntPtr fileEnumPtr = IntPtr.Zero;
            IntPtr folderEnumPtr = IntPtr.Zero;
            IntPtr pidlSub;
            int celtFetched;//获取子文件夹
            if (Root.EnumObjects(this.Handle, SHCONTF.FOLDERS | SHCONTF.INCLUDEHIDDEN, out fileEnumPtr) == API.S_OK)
            {
                fileEnum = (IEnumIDList)Marshal.GetObjectForIUnknown(fileEnumPtr);
                while (fileEnum.Next(1, out pidlSub, out celtFetched) == 0 && celtFetched == API.S_FALSE)
                {
                    //获取显示名称
                    string name = API.GetNameByPIDL(pidlSub);
                    lvFile.Items.Add(name, 1);
                }
            }//获取子文件
            if (Root.EnumObjects(this.Handle, SHCONTF.NONFOLDERS | SHCONTF.INCLUDEHIDDEN, out folderEnumPtr) == API.S_OK)
            {
                folderEnum = (IEnumIDList)Marshal.GetObjectForIUnknown(folderEnumPtr);
                while (folderEnum.Next(1, out pidlSub, out celtFetched) == 0 && celtFetched == API.S_FALSE)
                {
                    string name = API.GetNameByPIDL(pidlSub);
                    lvFile.Items.Add(name, 0);
                }
            }
            Marshal.ReleaseComObject(Root);
        }

下面是运行后的效果：