第四步 Provider Manager 类
这个类根据 第三步中的 Provider Configuration类中的配置信息，实例化Provider.
public sealed class IndexBuilderManager
{
//private static bool isInitialized = false; //private static Exception initializationException; private static object initializationLock = new object(); private static readonly ILog log = LogManager.GetLogger(typeof(IndexBuilderManager)); //在构造函数中调用初始化方法 static IndexBuilderManager()
{
Initialize();
} //根据配置文件中的信息,实例化provider，并放到ProviderCollection中 private static void Initialize() { providerCollection = new IndexBuilderProviderCollection(); try { IndexBuilderConfiguration config = IndexBuilderConfiguration.GetConfig(); if (config != null) { if ( (config.Providers == null) || (config.Providers.Count < 1) ) { throw new ProviderException("No IndexBuilderProvider found."); } //实例化Provider的具体方法 ProvidersHelper.InstantiateProviders( config.Providers, providerCollection, typeof(IndexBuilderProvider)); } else { // config was null, not a good thing log.Error("IndexBuilderConfiguration could not be loaded so empty provider collection was returned"); } } catch (NullReferenceException ex) { log.Error(ex); } catch (TypeInitializationException ex) { log.Error(ex); } catch (ProviderException ex) { log.Error(ex); } providerCollection.SetReadOnly(); //} //catch (Exception ex) //{ // log.Error(ex); // initializationException = ex; // isInitialized = false; // //throw ex; // return; //} //isInitialized = true; } private static IndexBuilderProviderCollection providerCollection; public static IndexBuilderProviderCollection Providers { get { //try //{ if (providerCollection == null) Initialize(); return providerCollection; //} //catch (NullReferenceException ex) //{ // log.Error(ex); //} //catch (TypeInitializationException ex) //{ // log.Error(ex); //} //catch (ProviderException ex) //{ // log.Error(ex); //} return null; } }
}