应用框架的设计与实现——.NET平台(6.获取外部配置信息)

使用 IConfigurationAgent 接口可以实现从外部资源获得配置数据。
配置文件的 Framework 节：


<configSections>


<section name="Framework" type="SAF.Configuration.ConfigurationHandler,SAF.Configuration" />


</configSections>


<Framework type="SAF.Configuration.ConfigurationManager,SAF.Configuration">


<SAF.Configuration>


<ConfigurationAgent>


<Agent name = "WSAgent1" type="TestConfigurationAgent.ConfigurationWSAgent,TestConfigurationAgent">


<Parameters>


<Section>SAF.ClassFactory</Section>


<Environment>QAEnvironment</Environment>


</Parameters>


<Url>http://localhost/ConfigurationData/ConfigurationService.asmx</Url>


</Agent>


</ConfigurationAgent>


</SAF.Configuration>


<SAF.ClassFactory ConfigurationAgent="WSAgent1"/>


</Framework>

配置管理类如何使用代理类的？
1.系统启动时读入配置文件，按照配置信息 Framework 节被交给 SAF.Configuration.ConfigurationManager 处理；
2.ConfigurationManager 建立一个 ConfigurationAgentManager 对象帮助获取配置信息；
3.当 ConfigurationManager 向 ConfigurationAgentManager 请求取得 SAF.ClassFactory 的配置信息时，
4.ConfigurationAgentManager 对象判断 SAF.ClassFactory 节是否有 ConfigurationAgent 属性，
4.1.如果此属性不存在则返回这个节的配置信息，
4.2.否则根据属性名找到对应的 Agent 节，使用节信息构造一个 IConfigurationAgent 对象，由这个对象取得配置信息，然后返回；
5.当 ConfigurationManager 取得返回信息后用返回信息构造 SAF.ClassFactory 节的配置对象。

使用代理类的顺序图：
<<csdn的blog真tmd的烂；上传文件更是让人绝望>>

ConfigurationManager －－配置段 Framework 的信息处理类




/**//// <summary>


/// Provides access to configuraiton object for the


/// framework component


/// </summary>


public class ConfigurationManager




...{


public SAF.Configuration.ServiceConfiguration ServiceConfig;


public SAF.Configuration.AuthorizationConfiguration AuthorizationConfig;


public SAF.Configuration.CryptographyConfiguration CryptographyConfig;


public SAF.Configuration.AuthenticationConfiguration AuthenticationConfig;


public SAF.Configuration.ClassFactoryConfiguration ClassFactoryConfig;


public SAF.Configuration.EventNotificationConfiguration EventNotificationConfig;


public SAF.Configuration.CacheConfigration CacheConfig;


public SAF.Configuration.MessageQueueConfiguration MessageQueueConfig;


private XmlNode configurationData;








/**//// <summary>


/// Initialize all the configuration objects accessible through


/// this configuration manager.


/// </summary>


/// <param name="sections"></param>


public ConfigurationManager (XmlNode sections)




...{


configurationData = sections;


ConfigurationAgentManager cam = new ConfigurationAgentManager(configurationData);


ServiceConfig = new ServiceConfiguration(cam.GetData("SAF.WindowsService"));


AuthorizationConfig = new AuthorizationConfiguration(cam.GetData("SAF.Authorization"));


CryptographyConfig = new CryptographyConfiguration(cam.GetData("SAF.Cryptography"));


AuthenticationConfig = new AuthenticationConfiguration(cam.GetData("SAF.Authentication"));


ClassFactoryConfig = new ClassFactoryConfiguration(cam.GetData("SAF.ClassFactory"));


EventNotificationConfig = new EventNotificationConfiguration(cam.GetData("SAF.EventNotification"));


MessageQueueConfig = new MessageQueueConfiguration(cam.GetData("SAF.MessageQueue"));


CacheConfig = new CacheConfigration(cam.GetData("SAF.Cache"));


}


}

ConfigurationAgentManager －－负责与代理对象打交道的管理类




/**//// <summary>


/// It is responsible for loading the agent object which


/// is responsible for retrieving the configuration data


/// </summary>


public class ConfigurationAgentManager




...{


private XmlNode configurationData;


public ConfigurationAgentManager(XmlNode configData)




...{


configurationData = configData;


}






/**//// <summary>


/// it return the Xml containing the configuraiton settings for a given key


/// </summary>


/// <param name="key">name of the Xml section in the configuration file, such as <SAF.ClassFactory>. </param>


/// <returns>XmlNode that contains the configuration settings </returns>


public XmlNode GetData(string key)




...{


XmlNode result=null;


XmlAttribute agentAttribute =null;


if (configurationData.SelectSingleNode(key) != null)




...{


//check if there is agent defined for a particular section or key


//if there is, load the agent and make it retrieve the data


//otherwise, just load the data from the configuraiton file


agentAttribute = configurationData.SelectSingleNode(key).Attributes["ConfigurationAgent"];


if ( agentAttribute == null)




...{


result = configurationData.SelectSingleNode(key);


}


else




...{


//retrive the data using the agent


string data = GetAgent(agentAttribute.Value).GetConfigurationSetting();


XmlDocument xml = new XmlDocument();


xml.LoadXml(data);


result = (XmlNode)xml.DocumentElement;


}


}


return result;


}






/**//// <summary>


/// the method load the agent using reflection and return an instance of agent


/// to the caller


/// </summary>


/// <param name="agentName">name of the agent referenced in the configuration file</param>


/// <returns>an agent object</returns>


private IConfigurationAgent GetAgent(string agentName)




...{


XmlNode agentNode = configurationData.SelectSingleNode("//Agent[@name ='" + agentName + "']");


Type type = Type.GetType(agentNode.Attributes["type"].Value);


IConfigurationAgent agent = (IConfigurationAgent)Activator.CreateInstance(type,null);


//Initialize method setup the agent object with the parameter information specified


//in the file that is needed for the agent to do its job


agent.Initialize(agentNode);


return agent;


}


}

IConfigurationAgent －－代理类接口




/**//// <summary>


/// Interface that each agent class must implement.


/// its two methods are called by agent manager at runtime.


/// </summary>


public interface IConfigurationAgent




...{


void Initialize(XmlNode xml);


string GetConfigurationSetting();


}

ConfigurationWSAgent －－ IConfigurationAgent 实现代理接口的一个范例类




/**//// <summary>


/// A sample Agent class that is responsible for retrieve configuration


/// data stored in other system via web service.


/// </summary>


public class ConfigurationWSAgent : IConfigurationAgent




...{


private string section;


private string environment;


private string url;




public ConfigurationWSAgent()...{}






/**//// <summary>


/// this method sets up the agent with parameters information


/// defined in the configuration file.


/// </summary>


/// <param name="configData"></param>


public void Initialize(XmlNode configData)




...{


section= configData.SelectSingleNode("Parameters/Section").InnerText;


environment = configData.SelectSingleNode("Parameters/Environment").InnerText;


url = configData.SelectSingleNode("Url").InnerText;


}






/**//// <summary>


/// this method call the web service and retrieve the actual configration data


/// </summary>


/// <returns>the configuration data</returns>


public string GetConfigurationSetting()




...{


localhost.ConfigurationService cs = new localhost.ConfigurationService();


cs.Url = url;


return cs.GetConfiguration(section,environment);


}


}