ASP.NET操作web.config

      ASP.NET可以利用WebConfigurationManager和直接利用XML方式操作web.config,WebConfigurationManager比较简单，但是清除注释代码。两者操作方式都需要有写权限。
      方法一，利用WebConfigurationManager，需要引用System.Web.Configuration.WebConfigurationManager；
     添加项：
     Configuration config = WebConfigurationManager.OpenWebConfiguration(null);
     AppSettingsSection app = config.AppSettings;
    app.Settings.Add("key", "valueadd");
    config.Save(ConfigurationSaveMode.Modified);
  
     修改项：
     Configuration config = WebConfigurationManager.OpenWebConfiguration(null);
     AppSettingsSection app = config.AppSettings;
     app.Settings["key"].Value = "valuemodify";
     config.Save(ConfigurationSaveMode.Modified);
     删除项：
     Configuration config = WebConfigurationManager.OpenWebConfiguration(null);
     AppSettingsSection app = config.AppSettings;
     app.Settings.Remove("key");
     config.Save(ConfigurationSaveMode.Modified);
     修改连接项：
      Configuration config = WebConfigurationManager.OpenWebConfiguration(Request.ApplicationPath);
ConnectionStringsSection conSection = (ConnectionStringsSection)config.GetSection("connectionStrings");
conSection.ConnectionStrings[Request["type"].ToString()].ConnectionString = Request["connstr"];
config.Save(ConfigurationSaveMode.Modified);
 XmlDocument xmldoc = new XmlDocument();
            string filename = Common.FilePath("../web.config");
    &nbs