有没有一种方法来覆盖ConfigurationManager.AppSettings？ [英] Is there a way to override ConfigurationManager.AppSettings?

问题描述

我真的希望能有办法把一个应用程序使用的 ConfigurationManager.AppSettings，目前获取其设置[mysettingkey] 以实际拥有这些设置来从集中式数据库，而不是app.config文件。我可以做一个自定义的配置部分，处理这样的事情，但我真的不希望其他开发商在我的球队不得不改变自己的code使用我的新DbConfiguration自定义栏目。我只是希望他们能够调用的AppSettings的方式，他们总是有，但它已经从一个中央数据库加载。

I really want to be able to have a way to take an app that currently gets its settings using ConfigurationManager.AppSettings["mysettingkey"] to actually have those settings come from a centralized database instead of the app.config file. I can make a custom config section for handling this sort of thing, but I really don't want other developers on my team to have to change their code to use my new DbConfiguration custom section. I just want them to be able to call AppSettings the way they always have but have it be loaded from a central database.

任何想法？

推荐答案

如果你不介意周围的框架黑客，你可以合理假设应用程序上运行的.NET Framework版本（即它是一个Web应用程序或Intranet应用程序），那么你可以尝试这样的：

If you don't mind hacking around the framework and you can reasonably assume the .net framework version the application is running on (i.e. it's a web application or an intranet application) then you could try something like this:

using System;
using System.Collections.Specialized;
using System.Configuration;
using System.Configuration.Internal;
using System.Reflection;

static class ConfigOverrideTest
{
  sealed class ConfigProxy:IInternalConfigSystem
  {
    readonly IInternalConfigSystem baseconf;

    public ConfigProxy(IInternalConfigSystem baseconf)
    {
      this.baseconf = baseconf;
    }

    object appsettings;
    public object GetSection(string configKey)
    {
      if(configKey == "appSettings" && this.appsettings != null) return this.appsettings;
      object o = baseconf.GetSection(configKey);
      if(configKey == "appSettings" && o is NameValueCollection)
      {
        // create a new collection because the underlying collection is read-only
        var cfg = new NameValueCollection((NameValueCollection)o);
        // add or replace your settings
        cfg["test"] = "Hello world";
        o = this.appsettings = cfg;
      }
      return o;
    }

    public void RefreshConfig(string sectionName)
    {
      if(sectionName == "appSettings") appsettings = null;
      baseconf.RefreshConfig(sectionName);
    }

    public bool SupportsUserConfig
    {
      get { return baseconf.SupportsUserConfig; }
    }
  }

  static void Main()
  {
    // initialize the ConfigurationManager
    object o = ConfigurationManager.AppSettings;
    // hack your proxy IInternalConfigSystem into the ConfigurationManager
    FieldInfo s_configSystem = typeof(ConfigurationManager).GetField("s_configSystem", BindingFlags.Static | BindingFlags.NonPublic);
    s_configSystem.SetValue(null, new ConfigProxy((IInternalConfigSystem)s_configSystem.GetValue(null)));
    // test it
    Console.WriteLine(ConfigurationManager.AppSettings["test"] == "Hello world" ? "Success!" : "Failure!");
  }
}

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