高分悬赏：如何根据文件的扩展名获取文件图标，并显示在页面上

Question

如题！谢谢

Answer 1

switch (ext.ToLower()){   
      case "txt":   
          currentTreeNode.ImageUrl = "images/ext_txt.gif";   
          break;   
      case "gif":   
          currentTreeNode.ImageUrl = "images/ext_gif.gif";   
          break;   
      ...   
}  

Answer 2

这个应该是事先准备好相关的图片的，即使是Windows操作系统，在没有安装相关软件的时候，文件的图标也是显示一个未知文件类型的图标楼主不会想要“牛”到所有的文件类型都能正确显示其图标吧

Answer 3

网上上的一个WPF的demo,就是实现这个功能的,lz可以看看代码
http://files.cnblogs.com/tengs2000/IconUtils.zip

Answer 4

using System;
using System.Runtime.InteropServices;
using System.Drawing;namespace MyNamespace
{
    public class FileIcon
    {
        /// <summary>
        ///  获取文件的默认图标
        /// </summary>
        /// <param name="fileName">文件名。
        ///     可以只是文件名，甚至只是文件的扩展名(.*)；
        ///     如果想获得.ICO文件所表示的图标，则必须是文件的完整路径。
        /// </param>
        /// <param name="largeIcon">是否大图标</param>
        /// <returns>文件的默认图标</returns>
        public static Icon GetFileIcon(string fileName, bool largeIcon)
        {
            SHFILEINFO info = new SHFILEINFO(true);
            int cbFileInfo = Marshal.SizeOf(info);
            SHGFI flags;
            if (largeIcon)
                flags = SHGFI.Icon | SHGFI.LargeIcon | SHGFI.UseFileAttributes;
            else
                flags = SHGFI.Icon | SHGFI.SmallIcon | SHGFI.UseFileAttributes;            SHGetFileInfo(fileName, 256, out info, (uint) cbFileInfo, flags);
            return Icon.FromHandle(info.hIcon);
        }
        [DllImport("Shell32.dll")]
        private static extern int SHGetFileInfo
          (
          string pszPath,
          uint dwFileAttributes,
          out   SHFILEINFO psfi,
          uint cbfileInfo,
          SHGFI uFlags
          );        [StructLayout(LayoutKind.Sequential)]
        private struct SHFILEINFO
        {
            public SHFILEINFO(bool b)
            {
                hIcon = IntPtr.Zero;
                iIcon = 0;
                dwAttributes = 0;
                szDisplayName = "";
                szTypeName = "";
            }
            public IntPtr hIcon;
            public int iIcon;
            public uint dwAttributes;
            [MarshalAs(UnmanagedType.LPStr, SizeConst = 260)]
            public string szDisplayName;
            [MarshalAs(UnmanagedType.LPStr, SizeConst = 80)]
            public string szTypeName;
        };        private enum SHGFI
        {
            SmallIcon = 0x00000001,
            LargeIcon = 0x00000000,
            Icon = 0x00000100,
            DisplayName = 0x00000200,
            Typename = 0x00000400,
            SysIconIndex = 0x00004000,
            UseFileAttributes = 0x00000010
        }
    }
}
以上代码可以实现你要的功能，不过嘛，遍历并呈现在web上并不是啥好方法，在web上应该尽量使用轻量级的东西，为了一个无伤大雅的小功能而无端的耗时间不划算啊

Answer 5

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;
namespace WindowsApplication2
{
    public partial class Form1 : Form
    {
        const uint SHGFI_ICON = 0x100;
        const uint SHGFI_USEFILEATTRIBUTES = 0x10;        [DllImport("Shell32", CharSet = CharSet.Auto)]
        internal extern static int ExtractIconEx(
            [MarshalAs(UnmanagedType.LPTStr)] 
string lpszFile,       //size of the icon
            int nIconIndex,        //index of the icon 
            //(in case we have more 
            //then 1 icon in the file
            IntPtr[] phIconLarge,  //32x32 icon
            IntPtr[] phIconSmall,  //16x16 icon
            int nIcons);           //how many to get        [DllImport("shell32.dll")]
        static extern IntPtr SHGetFileInfo(
            string pszPath,                //path
            uint dwFileAttributes,        //attributes
            ref SHFILEINFO psfi,        //struct pointer
            uint cbSizeFileInfo,        //size
            uint uFlags);    //flags        //we need this function to release the unmanaged resource,
        //the unmanaged resource will be 
        //copies to a managed one and it will be returned.
        [DllImport("user32.dll", CharSet = CharSet.Auto)]
        extern static bool DestroyIcon(IntPtr handle);
        struct SHFILEINFO
        {
            public IntPtr hIcon;
            public IntPtr iIcon;
            public uint dwAttributes;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]
            public string szDisplayName;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 80)]
            public string szTypeName;
        };
        public enum IconSize : uint
        {
            Large = 0x0,  //32x32
            Small = 0x1 //16x16        
        }
        public static Icon IconFromExtension(string Extension,
            IconSize Size)
        {
            try
            {
                Icon TempIcon;                //add '.' if nessesry
                if (Extension[0] != '.')
                    Extension = '.' + Extension;                //temp struct for getting file shell info
                SHFILEINFO TempFileInfo = new SHFILEINFO();                SHGetFileInfo(
                    Extension,
                    0,
                    ref TempFileInfo,
                    (uint)Marshal.SizeOf(TempFileInfo),
                    SHGFI_ICON | SHGFI_USEFILEATTRIBUTES | (uint)Size);                TempIcon = (Icon)Icon.FromHandle(TempFileInfo.hIcon);
                return GetManagedIcon(ref TempIcon);
            }
            catch (Exception e)
            {
                System.Diagnostics.Debug.WriteLine("error" +
                    " while trying to get icon for " +
                    Extension + " :" + e.Message);
                return null;
            }
        }
        public static Icon GetManagedIcon(ref Icon UnmanagedIcon)
        {
            Icon ManagedIcon = (Icon)UnmanagedIcon.Clone();            DestroyIcon(UnmanagedIcon.Handle);            return ManagedIcon;
        }
        public Form1()
        {
            InitializeComponent();
        }        private void Form1_Load(object sender, EventArgs e)
        {
            System.Drawing.Icon icon = IconFromExtension("txt", IconSize.Large);
            this.Icon = icon;
        }
    }
}

Answer 6

看看能不能找到系统图标的存放位置，不行的话看看能不能调系统api

Answer 7

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Drawing;
using System.Runtime.InteropServices;public partial class _Default : System.Web.UI.Page 
{
    const uint SHGFI_ICON = 0x100;
        const uint SHGFI_USEFILEATTRIBUTES = 0x10;        [DllImport("Shell32", CharSet = CharSet.Auto)]
        internal extern static int ExtractIconEx(
            [MarshalAs(UnmanagedType.LPTStr)] 
            string lpszFile,       //size of the icon
            int nIconIndex,        //index of the icon 
            //(in case we have more 
            //then 1 icon in the file
            IntPtr[] phIconLarge,  //32x32 icon
            IntPtr[] phIconSmall,  //16x16 icon
            int nIcons);           //how many to get        [DllImport("shell32.dll")]
        static extern IntPtr SHGetFileInfo(
            string pszPath,                //path
            uint dwFileAttributes,        //attributes
            ref SHFILEINFO psfi,        //struct pointer
            uint cbSizeFileInfo,        //size
            uint uFlags);    //flags        //we need this function to release the unmanaged resource,
        //the unmanaged resource will be 
        //copies to a managed one and it will be returned.
        [DllImport("user32.dll", CharSet = CharSet.Auto)]
        extern static bool DestroyIcon(IntPtr handle);
        struct SHFILEINFO
        {
            public IntPtr hIcon;
            public IntPtr iIcon;
            public uint dwAttributes;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]
            public string szDisplayName;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 80)]
            public string szTypeName;
        };
        public enum IconSize : uint
        {
            Large = 0x0,  //32x32
            Small = 0x1 //16x16        
        }
        public static Icon IconFromExtension(string Extension,
            IconSize Size)
        {
            try
            {
                Icon TempIcon;                //add '.' if nessesry
                if (Extension[0] != '.')
                    Extension = '.' + Extension;                //temp struct for getting file shell info
                SHFILEINFO TempFileInfo = new SHFILEINFO();                SHGetFileInfo(
                    Extension,
                    0,
                    ref TempFileInfo,
                    (uint)Marshal.SizeOf(TempFileInfo),
                    SHGFI_ICON | SHGFI_USEFILEATTRIBUTES | (uint)Size);                TempIcon = (Icon)Icon.FromHandle(TempFileInfo.hIcon);
                return GetManagedIcon(ref TempIcon);
            }
            catch (Exception e)
            {
                System.Diagnostics.Debug.WriteLine("error" +
                    " while trying to get icon for " +
                    Extension + " :" + e.Message);
                return null;
            }
        }
        public static Icon GetManagedIcon(ref Icon UnmanagedIcon)
        {
            Icon ManagedIcon = (Icon)UnmanagedIcon.Clone();            DestroyIcon(UnmanagedIcon.Handle);            return ManagedIcon;
        }    protected void Page_Load(object sender, EventArgs e)
    {
        Icon icon = IconFromExtension("rar", IconSize.Large);
        using(System.IO.MemoryStream ms=new System.IO.MemoryStream())
        {
            icon.ToBitmap().Save(this.Response.OutputStream,System.Drawing.Imaging.ImageFormat.Jpeg);
            ms.Close();
        }
    }
}