需要在客户端软件中保存用户的一些设置，比如是否在登录框中保存上次登录名等信息，就用到了.NET中的应用程序设置功能。如果使用用户范围的设置，程序会在磁盘上创建user.config用来存储修改后设置值，对 user.config所在的文件夹，我产生了一些兴趣，并做了一些研究。现举个例子来说明：
C:\Documents and Settings\Admin\Local Settings\Application Data\Microsoft\test.exe_Url_3ypvtlafqkef0gkp1kl5i2idjssaxajb\1.0.0.0\user.config
其中
“C:\Documents and Settings\Admin\Local Settings\Application Data”是LocalApplicationData特殊文件夹
“Microsoft”程序集的厂商名称
“Admin”是当前Windows用户名
“test.exe”是程序集友好名称
“1.0.0.0”是程序集版本
“user.config”是存储用户配置信息的文件的文件名
“Url_3ypvtlafqkef0gkp1kl5i2idjssaxajb”该字符串是将程序集的厂商信息、版本信息、绝对路径进行哈希计算，得到的唯一值，可避免不同的程序生成相同的文件路径。

如果要想通过编程的方式对user.config文件做一些灵活的控制，就必须得到该文件的绝对路径，为了获取.NET生成user.config唯

一路径的方法，笔者使用Reflector反编译了System.Config程序集，终于得到了其中的方法，做了一些简化。现做一些介绍：
（1）ClientConfigPaths类，只有一个public方法GetUserConfigFilePath，此方法即可获取user.config的绝对路径;
（2）StringUtil类，一个辅助类，用来做一些字符串操作
（3）使用方法：

  ClientConfigPaths ccp = new ClientConfigPaths();
  textBox1.Text = ccp.GetUserConfigFilePath();
以下的代码笔者做了一些简化的同时也做了一些限制，即只适用于从本地磁盘加载的程序集。
注意：如果是从internet加载或者使用clickonce部署的程序集请不要使用该方法。

    //ClientConfigPaths类
    using Microsoft.Win32;
    using System;
    using System.Collections;
    using System.Diagnostics;
    using System.Globalization;
    using System.IO;
    using System.Reflection;
    using System.Runtime.CompilerServices;
    using System.Runtime.InteropServices;
    using System.Runtime.Serialization.Formatters.Binary;
    using System.Security.Cryptography;
    using System.Security.Permissions;
    using System.Security.Policy;
    using System.Text;
    internal class ClientConfigPaths
    {
        private string _applicationConfigUri;
        private string _applicationUri;
        private string _companyName;
        private bool _includesUserConfig;
        private string _productName;
        private string _productVersion;
        private const string ClickOnceDataDirectory = "DataDirectory";
        private const string ConfigExtension = ".config";
        private const string FILE_URI = "file:";
        private const string FILE_URI_LOCAL = "file:///";
        private const string FILE_URI_UNC = "file://";
        private const string HTTP_URI = "http://";
        private const int MAX_LENGTH_TO_USE = 0x19;
        private const int MAX_PATH = 260;
        private const string PathDesc = "Path";
        private static char[] s_Base32Char = new char[] { 
            'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 
            'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5'
         };
        private static SecurityPermission s_controlEvidencePerm;
        private static SecurityPermission s_serializationPerm;
        private const string StrongNameDesc = "StrongName";
        private const string UrlDesc = "Url";
        internal const string UserConfigFilename = "user.config";

        public string GetUserConfigFilePath()
        {
            string exePath = null;
            bool includeUserConfig = true;
            string UserConfigFilePath = "";
            this._includesUserConfig = includeUserConfig;
            Assembly exeAssembly = null;
            string codeBase = null;
            string applicationFilename = null;
            if (exePath == null)
            {
                AppDomainSetup setupInformation = AppDomain.CurrentDomain.SetupInformation;
                this._applicationConfigUri = setupInformation.ConfigurationFile;
                exeAssembly = Assembly.GetEntryAssembly();
                    codeBase = exeAssembly.CodeBase;
                    bool flag = false;
                    if (StringUtil.StartsWithIgnoreCase(codeBase, "file:///"))
                    {
                        flag = true;
                        codeBase = codeBase.Substring("file:///".Length);
                    }
                    else if (StringUtil.StartsWithIgnoreCase(codeBase, "file://"))
                    {
                        flag = true;
                        codeBase = codeBase.Substring("file:".Length);
                    }
                    if (flag)
                    {
                        codeBase = codeBase.Replace('/', '\\');
                        applicationFilename = codeBase;
                    }
                    else
                    {
                        codeBase = exeAssembly.EscapedCodeBase;
                    }
            }
            else
            {
                codeBase = Path.GetFullPath(exePath);
                if (!File.Exists(codeBase))
                {
                    throw new Exception();
                }
                applicationFilename = codeBase;
            }
            if (this._applicationConfigUri == null)
            {
                this._applicationConfigUri = codeBase + ".config";
            }
            this._applicationUri = codeBase;
            if ((exePath == null) && this._includesUserConfig)
            {
                this.SetNamesAndVersion(applicationFilename, exeAssembly, false);

                string str5 = this.Validate(this._companyName, true);
                string str6 = this.Validate(AppDomain.CurrentDomain.FriendlyName, true);
                string str7 = !string.IsNullOrEmpty(this._applicationUri) ? this._applicationUri.ToLower

(CultureInfo.InvariantCulture) : null;
                string str8 = !string.IsNullOrEmpty(str6) ? str6 : this.Validate(this._productName, true);
                string typeAndHashSuffix = this.GetTypeAndHashSuffix(AppDomain.CurrentDomain, str7);
                    string str10 = (!string.IsNullOrEmpty(str8) && !string.IsNullOrEmpty(typeAndHashSuffix)) ? 

(str8 + typeAndHashSuffix) : null;
                    string str11 = this.Validate(this._productVersion, false);
                    string str12 = this.CombineIfValid(this.CombineIfValid(str5, str10), str11);
                    string path = Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData);
                    if (Path.IsPathRooted(path))
                    {
                        UserConfigFilePath = this.CombineIfValid(path, str12);
                        UserConfigFilePath = this.CombineIfValid(UserConfigFilePath, "user.config");
                    }
            }
            return UserConfigFilePath;
        }

        private string CombineIfValid(string path1, string path2)
        {
            string str = null;
            if ((path1 != null) && (path2 != null))
            {
                try
                {
                    string str2 = Path.Combine(path1, path2);
                    if (str2.Length < 260)
                    {
                        str = str2;
                    }
                }
                catch
                {
                }
            }
            return str;
        }

        private static object GetEvidenceInfo(AppDomain appDomain, string exePath, out string typeName)
        {
            ControlEvidencePermission.Assert();
            Evidence evidence = appDomain.Evidence;
            StrongName sn = null;
            Url url = null;
            if (evidence != null)
            {
                IEnumerator hostEnumerator = evidence.GetHostEnumerator();
                object current = null;
                while (hostEnumerator.MoveNext())
                {
                    current = hostEnumerator.Current;
                    if (current is StrongName)
                    {
                        sn = (StrongName) current;
                        break;
                    }
                    if (current is Url)
                    {
                        url = (Url) current;
                    }
                }
            }
            object obj3 = null;
            if (sn != null)
            {
                obj3 = MakeVersionIndependent(sn);
                typeName = "StrongName";
                return obj3;
            }
            if (url != null)
            {
                obj3 = url.Value.ToUpperInvariant();
                typeName = "Url";
                return obj3;
            }
            if (exePath != null)
            {
                obj3 = exePath;
                typeName = "Path";
                return obj3;
            }
            typeName = null;
            return obj3;
        }

        private static string GetHash(Stream s)
        {
            byte[] buffer;
            using (SHA1 sha = new SHA1CryptoServiceProvider())
            {
                buffer = sha.ComputeHash(s);
            }
            return ToBase32StringSuitableForDirName(buffer);
        }

        private string GetTypeAndHashSuffix(AppDomain appDomain, string exePath)
        {
            string str = null;
            string typeName = null;
            object graph = null;
            graph = GetEvidenceInfo(appDomain, exePath, out typeName);
            if ((graph != null) && !string.IsNullOrEmpty(typeName))
            {
                MemoryStream serializationStream = new MemoryStream();
                BinaryFormatter formatter = new BinaryFormatter();
                SerializationFormatterPermission.Assert();
                formatter.Serialize(serializationStream, graph);
                serializationStream.Position = 0L;
                string hash = GetHash(serializationStream);
                if (!string.IsNullOrEmpty(hash))
                {
                    str = "_" + typeName + "_" + hash;
                }
            }
            return str;
        }

        private static StrongName MakeVersionIndependent(StrongName sn)
        {
            return new StrongName(sn.PublicKey, sn.Name, new Version(0, 0, 0, 0));
        }

        private void SetNamesAndVersion(string applicationFilename, Assembly exeAssembly, bool isHttp)
        {
            Type reflectedType = null;
            if (exeAssembly != null)
            {
                object[] customAttributes = exeAssembly.GetCustomAttributes(typeof(AssemblyCompanyAttribute), 

false);
                if ((customAttributes != null) && (customAttributes.Length > 0))
                {
                    this._companyName = ((AssemblyCompanyAttribute) customAttributes[0]).Company;
                    if (this._companyName != null)
                    {
                        this._companyName = this._companyName.Trim();
                    }
                }
                customAttributes = exeAssembly.GetCustomAttributes(typeof(AssemblyProductAttribute), false);
                if ((customAttributes != null) && (customAttributes.Length > 0))
                {
                    this._productName = ((AssemblyProductAttribute) customAttributes[0]).Product;
                    if (this._productName != null)
                    {
                        this._productName = this._productName.Trim();
                    }
                }
                this._productVersion = exeAssembly.GetName().Version.ToString();
                if (this._productVersion != null)
                {
                    this._productVersion = this._productVersion.Trim();
                }
            }
            if (!isHttp && ((string.IsNullOrEmpty(this._companyName) || string.IsNullOrEmpty(this._productName)) || 

string.IsNullOrEmpty(this._productVersion)))
            {
                string fileName = null;
                if (exeAssembly != null)
                {
                    MethodInfo entryPoint = exeAssembly.EntryPoint;
                    if (entryPoint != null)
                    {
                        reflectedType = entryPoint.ReflectedType;
                        if (reflectedType != null)
                        {
                            fileName = reflectedType.Module.FullyQualifiedName;
                        }
                    }
                }
                if (fileName == null)
                {
                    fileName = applicationFilename;
                }
                if (fileName != null)
                {
                    FileVersionInfo versionInfo = FileVersionInfo.GetVersionInfo(fileName);
                    if (versionInfo != null)
                    {
                        if (string.IsNullOrEmpty(this._companyName))
                        {
                            this._companyName = versionInfo.CompanyName;
                            if (this._companyName != null)
                            {
                                this._companyName = this._companyName.Trim();
                            }
                        }
                        if (string.IsNullOrEmpty(this._productName))
                        {
                            this._productName = versionInfo.ProductName;
                            if (this._productName != null)
                            {
                                this._productName = this._productName.Trim();
                            }
                        }
                        if (string.IsNullOrEmpty(this._productVersion))
                        {
                            this._productVersion = versionInfo.ProductVersion;
                            if (this._productVersion != null)
                            {
                                this._productVersion = this._productVersion.Trim();
                            }
                        }
                    }
                }
            }
            if (string.IsNullOrEmpty(this._companyName) || string.IsNullOrEmpty(this._productName))
            {
                string str2 = null;
                if (reflectedType != null)
                {
                    str2 = reflectedType.Namespace;
                }
                if (string.IsNullOrEmpty(this._productName))
                {
                    if (str2 != null)
                    {
                        int num = str2.LastIndexOf(".", StringComparison.Ordinal);
                        if ((num != -1) && (num < (str2.Length - 1)))
                        {
                            this._productName = str2.Substring(num + 1);
                        }
                        else
                        {
                            this._productName = str2;
                        }
                        this._productName = this._productName.Trim();
                    }
                    if (string.IsNullOrEmpty(this._productName) && (reflectedType != null))
                    {
                        this._productName = reflectedType.Name.Trim();
                    }
                    if (this._productName == null)
                    {
                        this._productName = string.Empty;
                    }
                }
                if (string.IsNullOrEmpty(this._companyName))
                {
                    if (str2 != null)
                    {
                        int index = str2.IndexOf(".", StringComparison.Ordinal);
                        if (index != -1)
                        {
                            this._companyName = str2.Substring(0, index);
                        }
                        else
                        {
                            this._companyName = str2;
                        }
                        this._companyName = this._companyName.Trim();
                    }
                    if (string.IsNullOrEmpty(this._companyName))
                    {
                        this._companyName = this._productName;
                    }
                }
            }
            if (string.IsNullOrEmpty(this._productVersion))
            {
                this._productVersion = "1.0.0.0";
            }
        }

        private static string ToBase32StringSuitableForDirName(byte[] buff)
        {
            StringBuilder builder = new StringBuilder();
            int length = buff.Length;
            int num7 = 0;
            do
            {
                byte num = (num7 < length) ? buff[num7++] : ((byte) 0);
                byte num2 = (num7 < length) ? buff[num7++] : ((byte) 0);
                byte index = (num7 < length) ? buff[num7++] : ((byte) 0);
                byte num4 = (num7 < length) ? buff[num7++] : ((byte) 0);
                byte num5 = (num7 < length) ? buff[num7++] : ((byte) 0);
                builder.Append(s_Base32Char[num & 0x1f]);
                builder.Append(s_Base32Char[num2 & 0x1f]);
                builder.Append(s_Base32Char[index & 0x1f]);
                builder.Append(s_Base32Char[num4 & 0x1f]);
                builder.Append(s_Base32Char[num5 & 0x1f]);
                builder.Append(s_Base32Char[((num & 0xe0) >> 5) | ((num4 & 0x60) >> 2)]);
                builder.Append(s_Base32Char[((num2 & 0xe0) >> 5) | ((num5 & 0x60) >> 2)]);
                index = (byte) (index >> 5);
                if ((num4 & 0x80) != 0)
                {
                    index = (byte) (index | 8);
                }
                if ((num5 & 0x80) != 0)
                {
                    index = (byte) (index | 0x10);
                }
                builder.Append(s_Base32Char[index]);
            }
            while (num7 < length);
            return builder.ToString();
        }

        private string Validate(string str, bool limitSize)
        {
            string str2 = str;
            if (!string.IsNullOrEmpty(str2))
            {
                foreach (char ch in Path.GetInvalidFileNameChars())
                {
                    str2 = str2.Replace(ch, '_');
                }
                str2 = str2.Replace(' ', '_');
                if (limitSize)
                {
                    str2 = (str2.Length > 0x19) ? str2.Substring(0, 0x19) : str2;
                }
            }
            return str2;
        }

        private static SecurityPermission ControlEvidencePermission
        {
            get
            {
                if (s_controlEvidencePerm == null)
                {
                    s_controlEvidencePerm = new SecurityPermission(SecurityPermissionFlag.ControlEvidence);
                }
                return s_controlEvidencePerm;
            }
        }

        private static SecurityPermission SerializationFormatterPermission
        {
            get
            {
                if (s_serializationPerm == null)
                {
                    s_serializationPerm = new SecurityPermission(SecurityPermissionFlag.SerializationFormatter);
                }
                return s_serializationPerm;
            }
        }

    }
StringUtil类

  //StringUtil类
    using System;
    internal static class StringUtil
    {
        internal static bool EqualsIgnoreCase(string s1, string s2)
        {
            return string.Equals(s1, s2, StringComparison.OrdinalIgnoreCase);
        }

        internal static bool EqualsNE(string s1, string s2)
        {
            if (s1 == null)
            {
                s1 = string.Empty;
            }
            if (s2 == null)
            {
                s2 = string.Empty;
            }
            return string.Equals(s1, s2, StringComparison.Ordinal);
        }

        internal static string[] ObjectArrayToStringArray(object[] objectArray)
        {
            string[] array = new string[objectArray.Length];
            objectArray.CopyTo(array, 0);
            return array;
        }

        internal static bool StartsWith(string s1, string s2)
        {
            if (s2 == null)
            {
                return false;
            }
            return (0 == string.Compare(s1, 0, s2, 0, s2.Length, StringComparison.Ordinal));
        }

        internal static bool StartsWithIgnoreCase(string s1, string s2)
        {
            if (s2 == null)
            {
                return false;
            }
            return (0 == string.Compare(s1, 0, s2, 0, s2.Length, StringComparison.OrdinalIgnoreCase));
        }
    }