如何正确检索与 Windows 上的扩展关联的打开命令？

Question

我试图找出用于打开给定扩展名文件的可执行文件，因此如果扩展名没有，我可以显示该可执行文件的图标。

我知道 HKEY_CLASSES_ROOT 注册表项中文件类型的开放动词，但我发现它的值并不总是正确的。

例如，我目前在 OS X 上的 Parallels 中运行 Windows。PDF 文件的默认关联是 Safari。我通过资源管理器将默认关联更改为 Adob​​e Reader。注册表中的打开动词仍然是 Safari，但是当我双击 PDF 文件时，它会使用 Adob​​e Reader 打开。 32 位和 64 位注册表具有相同的值。

有没有更好的方法来检索文件类型的关联，无论是使用 .NET 还是 winapi？

Answer 1

您最好的选择可能是使用Assoc* 函数组，例如AssocQueryKey() 和AssocQueryString() via PInvoke。但是，我不知道 .NET 框架附带的众多类中的一个是否已经为您包装了它。但 Shell API 为您提供了检索此信息的选项。

还请注意备注部分，其中指出上述函数是IQueryAssociations 接口的包装器，这使得您更有可能从 .NET 中获得另一条更直接的途径。

旧式函数是这个：FindExecutable()。不过，不要使用它。它使用与ShellExecute() 相同的有缺陷的错误代码魔法。

另请参阅Windows: List and Launch applications associated with an extension 的答案

Answer 2

我的代码包括检查以防止一些常见错误...希望它有所帮助:-)

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");
    /// Usage: string command FileAssociation.GetExecCommandAssociatedToExtension(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 GetExecCommandAssociatedToExtension(string ext, string verb = null)
        {
            if (ext[0] != '.')
            {
                ext = "." + ext;
            }

            string  executablePath = FileExtentionInfo(AssocStr.Command, ext, verb);

            // 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;
        }

        /// <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
        }



    }
}

Answer 3

您还需要检查 HKEY_USERS\{User}\Software\Classes。用户可以覆盖他们自己的默认应用程序。