MonoRail/Castle.MonoRail.Framework/ServiceProviderLocator.cs

   1 // Copyright 2004-2007 Castle Project - http://www.castleproject.org/
   2 //
   3 // Licensed under the Apache License, Version 2.0 (the "License");
   4 // you may not use this file except in compliance with the License.
   5 // You may obtain a copy of the License at
   6 //
   7 //     http://www.apache.org/licenses/LICENSE-2.0
   8 //
   9 // Unless required by applicable law or agreed to in writing, software
  10 // distributed under the License is distributed on an "AS IS" BASIS,
  11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12 // See the License for the specific language governing permissions and
  13 // limitations under the License.
  14
  15 namespace Castle.MonoRail.Framework
  16 {
  17         using System.Collections.Generic;
  18         using System.Web;
  19         using Castle.Core;
  20
  21         /// <summary>
  22         /// Uses the HttpContext and the <see cref="IServiceProviderExAccessor"/>
  23         /// to access the container instance.
  24         /// </summary>
  25         public class ServiceProviderLocator : IServiceProviderLocator
  26         {
  27                 private static readonly ServiceProviderLocator instance = new ServiceProviderLocator();
  28
  29                 private readonly IList<IAccessorStrategy> locatorStrategies = new List<IAccessorStrategy>();
  30
  31                 /// <summary>
  32                 /// Initializes a new instance of the <see cref="ServiceProviderLocator"/> class.
  33                 /// </summary>
  34                 public ServiceProviderLocator()
  35                 {
  36                         AddLocatorStrategy(new ServiceProviderAccessorStrategy());
  37                 }
  38
  39                 /// <summary>
  40                 /// Gets the instance.
  41                 /// </summary>
  42                 /// <value>The instance.</value>
  43                 public static ServiceProviderLocator Instance
  44                 {
  45                         get { return instance; }
  46                 }
  47
  48                 /// <summary>
  49                 /// Locates the service provider using the registered strategies.
  50                 /// </summary>
  51                 /// <returns></returns>
  52                 public IServiceProviderEx LocateProvider()
  53                 {
  54                         foreach(IAccessorStrategy strategy in locatorStrategies)
  55                         {
  56                                 IServiceProviderEx serviceProvider = strategy.LocateProvider();
  57
  58                                 if (serviceProvider != null)
  59                                 {
  60                                         return serviceProvider;
  61                                 }
  62                         }
  63
  64                         return null;
  65                 }
  66
  67                 /// <summary>
  68                 /// Adds a locator strategy.
  69                 /// </summary>
  70                 /// <param name="strategy">The strategy.</param>
  71                 public void AddLocatorStrategy(IAccessorStrategy strategy)
  72                 {
  73                         locatorStrategies.Add(strategy);
  74                 }
  75
  76                 /// <summary>
  77                 /// Abstract an approach to access a <see cref="IServiceProviderEx"/>
  78                 /// </summary>
  79                 public interface IAccessorStrategy
  80                 {
  81                         /// <summary>
  82                         /// Locates the provider.
  83                         /// </summary>
  84                         /// <returns></returns>
  85                         IServiceProviderEx LocateProvider();
  86                 }
  87
  88                 /// <summary>
  89                 /// Default strategy to access a service provider
  90                 /// </summary>
  91                 public class ServiceProviderAccessorStrategy : IAccessorStrategy
  92                 {
  93                         /// <summary>
  94                         /// Locates the provider using the ApplicationInstance and casting it to
  95                         /// <see cref="IServiceProviderExAccessor"/>
  96                         /// </summary>
  97                         /// <returns></returns>
  98                         public IServiceProviderEx LocateProvider()
  99                         {
 100                                 IServiceProviderExAccessor containerAccessor =
 101                                         HttpContext.Current.ApplicationInstance as IServiceProviderExAccessor;
 102
 103                                 if (containerAccessor == null)
 104                                 {
 105                                         return null;
 106                                 }
 107
 108                                 return containerAccessor.ServiceProvider;
 109                         }
 110                 }
 111         }
 112 }