C# app.config配置appSettings标签

AppSettings标签主要用于应用程中的一些配置信息。比如上传文件的路径，需要用到的可能会根据不同环境改变的一些常量等。可以在配置文件添加可执行文件要的配置。

using System; using System.Collections.Generic; using System.Configuration;  class Program {     static void Main(string[] args)     {         string valstr;         string bl;                 bl =ReadAppSettings("Setting1",out valstr);         if (bl == "true")             Console.WriteLine("Setting1值：{0}", valstr);         else             Console.WriteLine("错误：" + bl);         bl = ReadAppSettings("Setting2", out valstr);         if (bl == "true")             Console.WriteLine("Setting2值：{0}", valstr);         else             Console.WriteLine("错误：" + bl);         bl = AddUpdateAppSettings("NewSetting", "May 7, 2014");         if (bl == "true")             Console.WriteLine("添加标签成功。");         else             Console.WriteLine("错误：" + bl);         bl = AddUpdateAppSettings("Setting1", "May 8, 2014");         if (bl == "true")             Console.WriteLine("修改标签成功。");         else             Console.WriteLine("错误：" + bl);          List<(string, string)> list;         bl = ReadAllAppSettings(out list);         if (bl == "true")             foreach (var val in list)             {                 Console.WriteLine("键：{0}， 值：{1}，", val.Item1, val.Item2);             }         else             Console.WriteLine("错误：" + bl);                Console.ReadKey();     }      /// <summary>     /// AppSettings标签读取全部值     /// </summary>     /// <param name="values">返回List<(string, string)>格式数据，使用out关键字。</param>     /// <returns>成功返回字符串“true”，失败返回原因。</returns>     public static string ReadAllAppSettings(out List<(string, string)> values)     {         values = null;         try         {             var appSettings = ConfigurationManager.AppSettings;             if (appSettings.Count == 0) { return "无AppSettings标签。"; }             values = new List<(string, string)>();             foreach (var key in appSettings.AllKeys)             {                 values.Add((key, appSettings[key]));             }             return "true";         }         catch (ConfigurationErrorsException err)         {             return err.Message;         }     }     /// <summary>     /// AppSettings标签读取指定值     /// </summary>     /// <param name="key">指定键</param>     /// <param name="val">输出值，使用out关键字</param>     /// <returns>成功返回字符串“true”，失败返回原因。</returns>     public static string ReadAppSettings(string key, out string val)     {         val = null;         try         {             var appSettings = ConfigurationManager.AppSettings;             val = appSettings[key];             if (val == null) return (key + "键值为空。");             if (val == "") return (key + "键值为空。");             return "true";         }         catch (ConfigurationErrorsException err)         {             return err.Message;         }     }     /// <summary>     /// AppSettings标签写入或更新配置数据     /// </summary>     /// <param name="key">键</param>     /// <param name="value">值</param>     /// <returns>成功返回字符串“true”，失败返回原因。</returns>     public static string AddUpdateAppSettings(string key, string value)     {         try         {             var configFile = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);             var settings = configFile.AppSettings.Settings;             if (settings[key] == null)                 settings.Add(key, value);             else                 settings[key].Value = value;             configFile.Save(ConfigurationSaveMode.Modified);             ConfigurationManager.RefreshSection(configFile.AppSettings.SectionInformation.Name);             return "true";         }         catch (ConfigurationErrorsException err)         {             return err.Message;         }     } }

第一次程序运行结果。

Setting1值：Not Found Setting1值：Not Found 键：NewSetting， 值：May 7, 2014， 键：Setting1， 值：May 8, 2014，

第一次程序运行后，ConsoleApp1.exe.Config数据，会创建<appSettings>标签，数据保存到标签内。

<?xml version="1.0" encoding="utf-8" ?> <configuration>     <appSettings>         <add key="NewSetting" value="May 7, 2014" />         <add key="Setting1" value="May 8, 2014" />     </appSettings>     <startup>          <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.7.2" />     </startup> </configuration>

第二次程序运行结果。

Setting1值：May 8, 2014 Setting1值：Not Found 键：NewSetting， 值：May 7, 2014， 键：Setting1， 值：May 8, 2014，

ConsoleApp1.exe.Config数据没有改变。