如何根据扩展名获取文件类型信息？c#中的(不是MIME)

Question

如何获得基于扩展的常规文件类型描述,就像资源管理器一样？所以不是MIME,而是最终用户看到的信息,比如.

.doc = Microsoft Office Word 97 - 2003文档.zip = ZIP文件.avi =视频文件.

我怎样才能获得似乎可用的"辅助"信息,我猜它不是基于扩展的.就像"视频文件"一样,它可以为您提供电影的"长度"或文档文件,它有多少页面等等.

Answer 1

谢谢Dan,好吧..这回答了我的第一个问题.可悲的不是第二个.注意:并非一切都打印..致PInvoke.net的积分

using System;
using System.Runtime.InteropServices;
using System.Text;
using System.Diagnostics;


namespace WindowsFormsApplication1
{
    static class Program
    {
        [DllImport("Shlwapi.dll", SetLastError = true, CharSet = CharSet.Auto)]
        static extern uint AssocQueryString(AssocF flags, AssocStr str, string pszAssoc, string pszExtra, [Out] StringBuilder pszOut, [In][Out] ref uint pcchOut);

        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main()
        {
            Debug.WriteLine(FileExtentionInfo(AssocStr.Command, ".doc"), "Command");
            Debug.WriteLine(FileExtentionInfo(AssocStr.DDEApplication, ".doc"), "DDEApplication");
            Debug.WriteLine(FileExtentionInfo(AssocStr.DDEIfExec, ".doc"), "DDEIfExec");
            Debug.WriteLine(FileExtentionInfo(AssocStr.DDETopic, ".doc"), "DDETopic");
            Debug.WriteLine(FileExtentionInfo(AssocStr.Executable, ".doc"), "Executable");
            Debug.WriteLine(FileExtentionInfo(AssocStr.FriendlyAppName, ".doc"), "FriendlyAppName");
            Debug.WriteLine(FileExtentionInfo(AssocStr.FriendlyDocName, ".doc"), "FriendlyDocName");
            Debug.WriteLine(FileExtentionInfo(AssocStr.NoOpen, ".doc"), "NoOpen");
            Debug.WriteLine(FileExtentionInfo(AssocStr.ShellNewValue, ".doc"), "ShellNewValue");

            //  DDEApplication: WinWord
            //DDEIfExec: Ñ??
            //  DDETopic: System
            //  Executable: C:\Program Files (x86)\Microsoft Office\Office12\WINWORD.EXE
            //  FriendlyAppName: Microsoft Office Word
            //  FriendlyDocName: Microsoft Office Word 97 - 2003 Document


        }

        public static string FileExtentionInfo(AssocStr assocStr, string doctype)
        {
            uint pcchOut = 0;
            AssocQueryString(AssocF.Verify, assocStr, doctype, null, null, ref pcchOut);

            StringBuilder pszOut = new StringBuilder((int)pcchOut);
            AssocQueryString(AssocF.Verify, assocStr, doctype, null, pszOut, ref pcchOut);
            return pszOut.ToString();
        }

        [Flags]
        public enum AssocF
        {
            Init_NoRemapCLSID = 0x1,
            Init_ByExeName = 0x2,
            Open_ByExeName = 0x2,
            Init_DefaultToStar = 0x4,
            Init_DefaultToFolder = 0x8,
            NoUserSettings = 0x10,
            NoTruncate = 0x20,
            Verify = 0x40,
            RemapRunDll = 0x80,
            NoFixUps = 0x100,
            IgnoreBaseClass = 0x200
        }

        public enum AssocStr
        {
            Command = 1,
            Executable,
            FriendlyDocName,
            FriendlyAppName,
            NoOpen,
            ShellNewValue,
            DDECommand,
            DDEIfExec,
            DDEApplication,
            DDETopic
        }

    }
}

Answer 2

我的代码包括检查以防止出现一些常见错误...希望对您有所帮助:-)

using System;
using System.Diagnostics;
using System.IO;
using System.Runtime.InteropServices;
using System.Text;

namespace HQ.Util.Unmanaged
{
    /// <summary>
    /// Usage:  string executablePath = FileAssociation.GetExecFileAssociatedToExtension(pathExtension, "open");
    /// </summary>
    public static class FileAssociation
    {
        /// <summary>
        /// 
        /// </summary>
        /// <param name="ext"></param>
        /// <param name="verb"></param>
        /// <returns>Return null if not found</returns>
        public static string GetExecFileAssociatedToExtension(string ext, string verb = null)
        {
            if (ext[0] != '.')
            {
                ext = "." + ext;
            }

            string executablePath = FileExtentionInfo(AssocStr.Executable, ext, verb); // Will only work for 'open' verb
            if (string.IsNullOrEmpty(executablePath))
            {
                executablePath = FileExtentionInfo(AssocStr.Command, ext, verb); // required to find command of any other verb than 'open'

                // Extract only the path
                if (!string.IsNullOrEmpty(executablePath) && executablePath.Length > 1) 
                {
                    if (executablePath[0] == '"')
                    {
                        executablePath = executablePath.Split('\"')[1];
                    }
                    else if (executablePath[0] == '\'')
                    {
                        executablePath = executablePath.Split('\'')[1];
                    }
                }
            }

            // Ensure to not return the default OpenWith.exe associated executable in Windows 8 or higher
            if (!string.IsNullOrEmpty(executablePath) && File.Exists(executablePath) &&
                !executablePath.ToLower().EndsWith(".dll"))
            {
                if (executablePath.ToLower().EndsWith("openwith.exe"))
                {
                    return null; // 'OpenWith.exe' is th windows 8 or higher default for unknown extensions. I don't want to have it as associted file
                }
                return executablePath;
            }
            return executablePath;
        }

        [DllImport("Shlwapi.dll", SetLastError = true, CharSet = CharSet.Auto)]
        static extern uint AssocQueryString(AssocF flags, AssocStr str, string pszAssoc, string pszExtra, [Out] StringBuilder pszOut, [In][Out] ref uint pcchOut);

        private static string FileExtentionInfo(AssocStr assocStr, string doctype, string verb)
        {
            uint pcchOut = 0;
            AssocQueryString(AssocF.Verify, assocStr, doctype, verb, null, ref pcchOut);

            Debug.Assert(pcchOut != 0);
            if (pcchOut == 0)
            {
                return "";
            }

            StringBuilder pszOut = new StringBuilder((int)pcchOut);
            AssocQueryString(AssocF.Verify, assocStr, doctype, verb, pszOut, ref pcchOut);
            return pszOut.ToString();
        }

        [Flags]
        public enum AssocF
        {
            Init_NoRemapCLSID = 0x1,
            Init_ByExeName = 0x2,
            Open_ByExeName = 0x2,
            Init_DefaultToStar = 0x4,
            Init_DefaultToFolder = 0x8,
            NoUserSettings = 0x10,
            NoTruncate = 0x20,
            Verify = 0x40,
            RemapRunDll = 0x80,
            NoFixUps = 0x100,
            IgnoreBaseClass = 0x200
        }

        public enum AssocStr
        {
            Command = 1,
            Executable,
            FriendlyDocName,
            FriendlyAppName,
            NoOpen,
            ShellNewValue,
            DDECommand,
            DDEIfExec,
            DDEApplication,
            DDETopic
        }



    }
}