MappingHandlerFactory.cs :  » Inversion-of-Control-Dependency-Injection » Spring.net » Spring » Web » Support » C# / CSharp Open Source

#region License

/*
 * Copyright  2002-2008 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#endregion

#region Imports

using System.Collections;
using System.Net;
using System.Web;
using Spring.Context;
using Spring.Context.Support;

#endregion

namespace Spring.Web.Support{
  /// <summary>
  /// MappingHandleryFactory allows for full Spring-managed &lt;httpHandlers&gt; configuration. 
  /// It uses regular expressions for url matching.
  /// </summary>
  /// <remarks>
  /// <example>
  /// The example below shows, how to map all url requests to spring and let
  /// <see cref="MappingHandlerFactory"/> resolve urls to container-managed <see cref="IHttpHandlerFactory"/> or <see cref="IHttpHandler"/> objects.
  /// <code>
    /// // web.config
    /// 
    /// &lt;httpHandlers&gt;
    ///   &lt;!-- map all requests to spring (just for demo - don't do this at home!) --&gt;
    ///   &lt;add verb=&quot;*&quot; path=&quot;*.*&quot; type=&quot;Spring.Web.Support.MappingHandlerFactory, Spring.Web&quot; /&gt;
    /// &lt;/httpHandlers&gt;
    /// 
    /// // spring-objects.config
    /// 
    /// &lt;object type=&quot;Spring.Web.Support.MappingHandlerFactoryConfigurer, Spring.Web&quot;&gt;
    ///   &lt;property name=&quot;HandlerMap&quot;&gt;
    ///     &lt;dictionary&gt;
    ///         &lt;entry key=&quot;\.ashx$&quot; value=&quot;standardHandlerFactory&quot; /&gt;
    ///         &lt;!-- map any request ending with *.whatever to standardHandlerFactory --&gt;
    ///         &lt;entry key=&quot;\.whatever$&quot; value=&quot;specialHandlerFactory&quot; /&gt;
    ///     &lt;/dictionary&gt;
    ///   &lt;/property&gt;
    /// &lt;/object&gt;
    /// 
    /// &lt;object name=&quot;standardHandlerFactory&quot; type=&quot;Spring.Web.Support.DefaultHandlerFactory, Spring.Web&quot; /&gt;
    /// 
    /// &lt;object name=&quot;specialHandlerFactory&quot; type=&quot;MySpecialHandlerFactoryImpl&quot; /&gt;
  /// </code>
  /// </example>
  /// </remarks>
  /// <seealso cref="IHttpHandlerFactory"/>
  /// <seealso cref="IHttpHandler"/>
  /// <seealso cref="HandlerMap"/>
  /// <seealso cref="MappingHandlerFactoryConfigurer"/>
  /// <author>Erich Eichinger</author>
  public class MappingHandlerFactory : AbstractHandlerFactory
  {
    private static readonly HandlerMap s_handlerMap = new HandlerMap();

        /// <summary>
        /// Holds the global list of mappings from url patterns to handler names.
        /// </summary>
    public static HandlerMap HandlerMap
    {
      get { return s_handlerMap; }
    }

        /// <summary>
        /// Holds the cache of handler/factory pairs handed out by this factory. This is required 
        /// for proper handling of <see cref="IHttpHandlerFactory.ReleaseHandler"/>.
        /// </summary>
    private readonly Hashtable _handlerWithFactoryTable = new Hashtable();

      /// <summary>
      /// Create a handler instance for the given URL. Will try to find a match of <paramref name="rawUrl"/> onto patterns in <see cref="HandlerMap"/>. 
      /// If a match is found, delegates the call to the matching <see cref="IHttpHandlerFactory.GetHandler"/> method.
      /// </summary>
      /// <param name="appContext">the application context corresponding to the current request</param>
      /// <param name="context">The <see cref="HttpContext"/> instance for this request.</param>
      /// <param name="requestType">The HTTP data transfer method (GET, POST, ...)</param>
      /// <param name="rawUrl">The requested <see cref="HttpRequest.RawUrl"/>.</param>
      /// <param name="physicalPath">The physical path of the requested resource.</param>
      /// <returns>A handler instance for processing the current request.</returns>
      protected override IHttpHandler CreateHandlerInstance(IConfigurableApplicationContext appContext, HttpContext context, string requestType, string rawUrl, string physicalPath)
      {
          return MapHandlerInstance(appContext, context, requestType, rawUrl, physicalPath, s_handlerMap, _handlerWithFactoryTable);
      }

        /// <summary>
        /// Obtains a handler by mapping <paramref name="rawUrl"/> to the list of patterns in <paramref name="handlerMappings"/>.
        /// </summary>
      /// <param name="appContext">the application context corresponding to the current request</param>
      /// <param name="context">The <see cref="HttpContext"/> instance for this request.</param>
      /// <param name="requestType">The HTTP data transfer method (GET, POST, ...)</param>
      /// <param name="rawUrl">The requested <see cref="HttpRequest.RawUrl"/>.</param>
      /// <param name="physicalPath">The physical path of the requested resource.</param>
        /// <param name="handlerMappings"></param>
        /// <param name="handlerWithFactoryTable"></param>
      /// <returns>A handler instance for processing the current request.</returns>
      protected IHttpHandler MapHandlerInstance(IConfigurableApplicationContext appContext, HttpContext context, string requestType, string rawUrl, string physicalPath, HandlerMap handlerMappings, IDictionary handlerWithFactoryTable)
      {
            // resolve handler instance by mapping the url to the list of patterns
          HandlerMapEntry handlerMapEntry = handlerMappings.MapPath(rawUrl);
          if (handlerMapEntry == null)
          {
              throw new HttpException(404, HttpStatusCode.NotFound.ToString());
          }
          object handlerObject = appContext.GetObject(handlerMapEntry.HandlerObjectName);

          if (handlerObject is IHttpHandler)
          {
              return (IHttpHandler) handlerObject;
          }
          else if (handlerObject is IHttpHandlerFactory)
          {
                // keep a reference to the issuing factory for later ReleaseHandler call
              IHttpHandlerFactory factory = (IHttpHandlerFactory) handlerObject;
              IHttpHandler handler = factory.GetHandler(context, requestType, rawUrl, physicalPath);
              lock(handlerWithFactoryTable.SyncRoot)
              {
                  handlerWithFactoryTable.Add(handler, factory);
              }
              return handler;
          }

          throw new HttpException((int)HttpStatusCode.NotFound, HttpStatusCode.NotFound.ToString());
      }

      /// <summary>
      /// Enables a factory to release an existing
      /// <see cref="System.Web.IHttpHandler"/> instance.
      /// </summary>
      /// <param name="handler">
      /// The <see cref="System.Web.IHttpHandler"/> object to release.
      /// </param>
      public override void ReleaseHandler(IHttpHandler handler)
    {
            ReleaseHandler(handler, this._handlerWithFactoryTable);
    }

        /// <summary>
        /// Removes the handler from the handler/factory dictionary and releases the handler.
        /// </summary>
        /// <param name="handler">the handler to be released</param>
        /// <param name="_handlerWithFactoryTable">a dictionary containing (<see cref="IHttpHandler"/>, <see cref="IHttpHandlerFactory"/>) entries.</param>
        protected void ReleaseHandler( IHttpHandler handler, IDictionary _handlerWithFactoryTable )
        {
        lock (_handlerWithFactoryTable.SyncRoot)
        {
            IHttpHandlerFactory factory = _handlerWithFactoryTable[handler] as IHttpHandlerFactory;
            if (factory != null)
            {
                _handlerWithFactoryTable.Remove(handler);
                factory.ReleaseHandler(handler);
            }            
        }            
        }
  }
}