今天做一个windows插件式服务程序，插件有时要读取配置文件的设置，但是服务是动态加载到服务上的，没有办法作到动态修改服务的配置文件（app.config)。在.net 2.0中有一个ConfigurationManager类可以方面的读取默认的配置文件，如果要自定义读取配置文件，这个类也提供了方法，如下所示：
var configMap = new ExeConfigurationFileMap { ExeConfigFilename = configFile };
var config = ConfigurationManager.OpenMappedExeConfiguration(configMap, ConfigurationUserLevel.None);
var configurationSection = config.GetSection(sectionName);
这种获取到的对象只是这个Section的名称和xml内容，这和ConfigurationManager默认方法GetSection获取到的是一个对象，可以进行强制转换成相应的类型相比，十分的不方便。
在不想造*想法，在google中搜索了很久也没有找到好的解决方法。最后，还是自己研究解决。
在上面的对象“configurationSection”是一个DefaultSection的类型，它有一个属性SectionInformation，如下所示：
public System.Configuration.SectionInformation SectionInformation { get; }
这个属性包含了从配置文件中读取到的xml信息，其中这个类型一个关键方法：
public string GetRawXml()
用于获取配置中的xml内容，举例如下：
有如下配置文件：
1: <configuration>
2: <configSections>
3: <sectionGroup name="WeiboClientSectionGroup">
4: <section name="SinaSection" type="System.Configuration.NameValueSectionHandler,System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/>
5: <section name="QQSection" type="System.Configuration.NameValueSectionHandler,System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/>
6: <section name="SohuSection" type="System.Configuration.NameValueSectionHandler,System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/>
7: <section name="NetEaseSection" type="System.Configuration.NameValueSectionHandler,System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/>
8: </sectionGroup>
9: <sectionGroup name="WeiboSectionGroup">
10: <section name="SinaSection" type="System.Configuration.NameValueSectionHandler,System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/>
11: <section name="QQSection" type="System.Configuration.NameValueSectionHandler,System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/>
12: <section name="SohuSection" type="System.Configuration.NameValueSectionHandler,System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/>
13: <section name="NetEaseSection" type="System.Configuration.NameValueSectionHandler,System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/>
14: </sectionGroup>
15: </configSections>
16: <WeiboClientSectionGroup>
17: <SinaSection>
18: <add key="AccessToken" value=""/>
19: <add key="AccessTokenSecret" value=""/>
20: <add key="ResultFormat" value="Json"/>
21: </SinaSection>
22: <!--<QQSection>
23: <add key="AccessToken" value=""/>
24: <add key="AccessTokenSecret" value=""/>
25: <add key="ResultFormat" value="Json"/>
26: </QQSection>-->
27: <QQSection>
28: <add key="AccessToken" value=""/>
29: <add key="AccessTokenSecret" value=""/>
30: <add key="ResultFormat" value="Json"/>
31: </QQSection>
32:
33: <SohuSection>
34: <add key="AccessToken" value=""/>
35: <add key="AccessTokenSecret" value=""/>
36: <add key="ResultFormat" value="Json"/>
37: </SohuSection>
38: <NetEaseSection>
39: <add key="AccessToken" value=""/>
40: <add key="AccessTokenSecret" value=""/>
41: <add key="ResultFormat" value="Json"/>
42: </NetEaseSection>
43: </WeiboClientSectionGroup>
44: <WeiboSectionGroup>
45: <SinaSection>
46: <add key="AppKey" value=""/>
47: <add key="AppSecret" value=""/>
48: <add key="AuthorizeUri" value="http://api.t.sina.com.cn/oauth/authorize"/>
49: <add key="RequestTokenUri" value="http://api.t.sina.com.cn/oauth/request_token"/>
50: <add key="AccessTokenUri" value="http://api.t.sina.com.cn/oauth/access_token"/>
51: <add key="CallBackUri" value="null"></add>
52: </SinaSection>
53: <QQSection>
54: <add key="AppKey" value=""/>
55: <add key="AppSecret" value=""/>
56: <add key="AuthorizeUri" value="https://open.t.qq.com/cgi-bin/authorize"/>
57: <add key="RequestTokenUri" value="https://open.t.qq.com/cgi-bin/request_token"/>
58: <add key="AccessTokenUri" value="https://open.t.qq.com/cgi-bin/access_token"/>
59: <add key="CallBackUri" value="null"></add>
60: </QQSection>
61: <SohuSection>
62: <add key="AppKey" value=""/>
63: <add key="AppSecret" value=""/>
64: <add key="AuthorizeUri" value="http://api.t.sohu.com/oauth/authorize"/>
65: <add key="RequestTokenUri" value="http://api.t.sohu.com/oauth/request_token"/>
66: <add key="AccessTokenUri" value="http://api.t.sohu.com/oauth/access_token"/>
67: <add key="CallBackUri" value="null"></add>
68: </SohuSection>
69: <NetEaseSection>
70: <add key="AppKey" value=""/>
71: <add key="AppSecret" value=""/>
72: <add key="AuthorizeUri" value="http://api.t.163.com/oauth/authenticate"/>
73: <add key="RequestTokenUri" value="http://api.t.163.com/oauth/request_token"/>
74: <add key="AccessTokenUri" value="http://api.t.163.com/oauth/access_token"/>
75: <add key="CallBackUri" value="null"></add>
76: </NetEaseSection>
77: </WeiboSectionGroup>
78: <startup><supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0"/></startup></configuration>
我们sectionName=”WeiboSectionGroup/SinaSection”
上面的函数就返回如下字符串：
<SinaSection>
<add key="AppKey" value=""/>
<add key="AppSecret" value=""/>
<add key="AuthorizeUri" value="http://api.t.sina.com.cn/oauth/authorize"/>
<add key="RequestTokenUri" value="http://api.t.sina.com.cn/oauth/request_token"/>
<add key="AccessTokenUri" value="http://api.t.sina.com.cn/oauth/access_token"/>
<add key="CallBackUri" value="null"></add>
</SinaSection>
另外此类型，还有一个Type属性，是字符串类型，如上面的配置，读取出来就是“
System.Configuration.NameValueSectionHandler,System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089
”
根据上面的信息，我们就可以首先使用反射的方式，生成对象NameValueSectionHandler，现调用此对的Create方法进行创建NameValueCollection，如下所示：
private static TReturn LoadSection<TReturn>(SectionInformation information) where TReturn:class
{
string[] strs = information.Type.Split(",".ToCharArray(), 2);
var handler = (IConfigurationSectionHandler)Assembly.Load(strs[1]).CreateInstance(strs[0]);
var doc = new XmlDocument();
doc.LoadXml(information.GetRawXml());
if (handler != null)
return (TReturn)handler.Create(null, null, doc.ChildNodes[0]);
return null;
}
下面提供一个完整的实例：
1: public abstract class ConfigBase<T> where T:class
2: {
3: protected ConfigBase(string sectionName, string configFile)
4: {
5: if (string.IsNullOrEmpty(configFile))
6: {
7: Section = (T)ConfigurationManager.GetSection(sectionName);
8: }
9: else
10: {
11: var configMap = new ExeConfigurationFileMap { ExeConfigFilename = configFile };
12: var config = ConfigurationManager.OpenMappedExeConfiguration(configMap, ConfigurationUserLevel.None);
13: var configurationSection = config.GetSection(sectionName);
14: if (configurationSection != null)
15: {
16: Section = LoadSection(configurationSection.SectionInformation);
17: }
18: }
19: }
20:
21: private static TReturn LoadSection<TReturn>(SectionInformation information) where TReturn:class
22: {
23: string[] strs = information.Type.Split(",".ToCharArray(), 2);
24: var handler = (IConfigurationSectionHandler)Assembly.Load(strs[1]).CreateInstance(strs[0]);
25: var doc = new XmlDocument();
26: doc.LoadXml(information.GetRawXml());
27: if (handler != null)
28: return (TReturn)handler.Create(null, null, doc.ChildNodes[0]);
29: return null;
30: }
31:
32: protected T LoadSection(SectionInformation information)
33: {
34: return LoadSection<T>(information);
35: }
36:
37: protected T Section { get; private set; }
38: }
上面是一个抽象类，从上面的类进行继承，就可以实现功能，如下所示：
1: public class ClientConfig : ConfigBase<NameValueCollection>
2: {
3: public ClientConfig(WeiboType weiboType)
4: : this(weiboType, null)
5: {
6: }
7:
8: public ClientConfig(WeiboType weiboType, string configFile)
9: : base(string.Format("WeiboClientSectionGroup/{0}Section", weiboType), configFile)
10: {
11: }
12:
13: public string AccessToken
14: {
15: get { return Section["AccessToken"]; }
16: }
17:
18: public string AccessTokenSecret
19: {
20: get { return Section["AccessTokenSecret"]; }
21: }
22:
23: public ResultFormat ResultFormat
24: {
25: get { return (ResultFormat)Enum.Parse(typeof(ResultFormat), Section["ResultFormat"]); }
26: }
27: }