mojoPortalprovider模式学习之1.1之IndexBuilderManager

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;
            }
        }
    }