需求:
什么时候会用到动态改变Web.config内的值?
在Web.config定义了一个全局设置值A,因为程序运行中满足了某个条件,要将A的值改变
Web.config中定义:
<appSettings>
<add key="IsChangeDb" value="false"/>
</appSettings>
获取Web.config中指定配置:
//获取web.config中 定义在appSetting中定义的配置
var item = ConfigurationManager.AppSettings["IsChangeDb"];
//根据我自己的需要转换成bool值
bool isChangeDb = string.IsNullOrEmpty(ConfigurationManager.AppSettings["IsChangeDb"]) ? false : bool.Parse(ConfigurationManager.AppSettings["IsChangeDb"]);
代码中更改Web.config中指定配置:
Configuration config=System.Web.Configuration.WebConfigurationManager.OpenWebConfiguration("~");
config.AppSettings.Settings.Remove("IsChangeDb");
config.AppSettings.Settings.Add("IsChangeDb", "true");
config.Save();
参考资料:
http://stackoverflow.com/questions/719928/how-do-you-modify-the-web-config-appsettings-at-runtime
出处：https://blog.csdn.net/qq_32452623/article/details/53580093
============================================================================
asp.net2.0新添加了对web.config直接操作的功能。开发的时候有可能用到在web.config里设置配置文件，其实是可以通过程序来设置这些配置节的。
asp.net2.0需要添加引用：
using System.Web.Configuration;
web.config里的配置节：
<appSettings>
<add key="FilePath" value="g:\Test\WebConfigManager\Upload\" />
<add key="p" value="g:\" />
</appSettings>
（1）读
string
filepath
=
ConfigurationManager.AppSettings[
"
FilePath
"
];
（2）添加
Configuration config
=
WebConfigurationManager.OpenWebConfiguration(
"
/WebConfigManager
"
);
AppSettingsSection app = config.AppSettings;
app.Settings.Add( " p " , " p:\\ " );
config.Save(ConfigurationSaveMode.Modified);
AppSettingsSection app = config.AppSettings;
app.Settings.Add( " p " , " p:\\ " );
config.Save(ConfigurationSaveMode.Modified);
（3）修改
Configuration config
=
WebConfigurationManager.OpenWebConfiguration(
"
/WebConfigManager
"
);
AppSettingsSection app = config.AppSettings;
app.Settings[ " p " ].Value = @" g:\ " ;
config.Save(ConfigurationSaveMode.Modified);
AppSettingsSection app = config.AppSettings;
app.Settings[ " p " ].Value = @" g:\ " ;
config.Save(ConfigurationSaveMode.Modified);
（4）删除
Configuration config
=
WebConfigurationManager.OpenWebConfiguration(
"
/WebConfigManager
"
);
AppSettingsSection app = config.AppSettings;
app.Settings.Remove( " p " );
config.Save(ConfigurationSaveMode.Modified);
AppSettingsSection app = config.AppSettings;
app.Settings.Remove( " p " );
config.Save(ConfigurationSaveMode.Modified);
注意：
（1）asp.net用户需要有读取、修改、写入的权限。
（2）
WebConfigManager是web.config所在的文件夹名。
出处：https://www.cnblogs.com/xxtkong/archive/2011/10/14/2211793.html
==============================================================================
通过从网上的了解，和学习，我们看到ConfigurationManager.OpenMappedExeConfiguration这个方法可以用于打开指定的配置文件，那么看看我们用它来做一些事情吧，下面看代码：
using System; using System.Collections.Generic; using System.Configuration; using System.Linq; using System.Text; using System.Threading.Tasks; using System.Web.Configuration; namespace PVG.Lib.Configs { public class WebConfigHelper { /// <summary> /// 是否加密连接字符串 /// </summary> public bool IsEncryptionConnection { get; set; } private Configuration config = null; public Configuration Configuration { get { return config; } set { config = value; } } public WebConfigHelper() { config = WebConfigurationManager.OpenWebConfiguration("~"); } /// <summary> /// 读取ConnectionStrings /// </summary> /// <param name="ConnName"></param> /// <returns></returns> public string GetConnectionStrings(string ConnName) { string res = ""; if (config != null && config.ConnectionStrings.ConnectionStrings[ConnName] != null) res = config.ConnectionStrings.ConnectionStrings[ConnName].ConnectionString; return res; } public string SetConnectionStrings(string ConnName, string ConnValue) { return SetConnectionStrings(ConnName, ConnValue, ""); } public string SetConnectionStrings(string ConnName, string ConnValue, string providerName) { if (config != null) { if (config.ConnectionStrings.ConnectionStrings[ConnName] != null) config.ConnectionStrings.ConnectionStrings[ConnName].ConnectionString = ConnValue; else config.ConnectionStrings.ConnectionStrings.Add(new ConnectionStringSettings(ConnName, ConnValue, providerName)); config.Save(ConfigurationSaveMode.Modified); } if (IsEncryptionConnection) encryptionConn();//加密配置项 return GetConnectionStrings(ConnName); } public string GetAppSettings(string keyName) { string res = ""; if (config != null && config.AppSettings.Settings[keyName] != null) res = config.AppSettings.Settings[keyName].Value; return res; } public string SetAppSettings(string keyName, string keyValue) { if (config != null) { if (config.AppSettings.Settings[keyName] != null) config.AppSettings.Settings[keyName].Value = keyValue; else config.AppSettings.Settings.Add(keyName, keyValue); config.Save(ConfigurationSaveMode.Modified); } return GetAppSettings(keyName); } private void encryptionConn() { ConfigurationSection connectionSection = config.GetSection("connectionStrings"); if (connectionSection != null) { connectionSection.SectionInformation.ProtectSection("RSAProtectedConfigurationProvider"); config.Save(); } } } }