WebContextFactory


1   /*
2    * Copyright 2005 Joe Walker
3    *
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    *
8    *     http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  package org.directwebremoting;
17  
18  import javax.servlet.ServletConfig  ;
19  import javax.servlet.ServletContext  ;
20  import javax.servlet.http.HttpServletRequest  ;
21  import javax.servlet.http.HttpServletResponse  ;
22  
23  /**
24   * Accessor for the current WebContext.
25   * @author Joe Walker [joe at getahead dot ltd dot uk]
26   */
27  public class WebContextFactory
28  {
29      /**
30       * Accessor for the current WebContext.
31       * @return The current WebContext or null if the current thread was not
32       * started by DWR.
33       */
34      public static WebContext get()
35      {
36          if (builder == null)
37          {
38              return null;
39          }
40  
41          return builder.get();
42      }
43  
44      /**
45       * Internal method to allow us to get the WebContextBuilder from which we
46       * will get WebContext objects.
47       * Do not call this method from outside of DWR.
48       * @param builder The factory object (from DwrServlet)
49       */
50      public static void setWebContextBuilder(WebContextBuilder builder)
51      {
52          WebContextFactory.builder = builder;
53      }
54  
55      /**
56       * The WebContextBuilder from which we will get WebContext objects
57       */
58      private static WebContextBuilder builder;
59  
60      /**
61       * Class to enable us to access servlet parameters.
62       */
63      public interface WebContextBuilder
64      {
65          /**
66           * Make the current thread know what the current request is.
67           * This method is only for use internally to DWR.
68           * @param request The incoming http request
69           * @param response The outgoing http reply
70           * @param config The servlet configuration
71           * @param context The servlet context
72           * @param container The IoC container
73           * @see #unset()
74           */
75          void set(HttpServletRequest   request, HttpServletResponse   response, ServletConfig   config, ServletContext   context, Container container);
76  
77          /**
78           * @return The WebContext that is associated with this thread
79           */
80          WebContext get();
81  
82          /**
83           * Unset the current ExecutionContext
84           * This method is only for use internally to DWR.
85           * @see #set(HttpServletRequest, HttpServletResponse, ServletConfig, ServletContext, Container)
86           */
87          void unset();
88      }
89  }
90
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