WebContext


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 java.io.IOException  ;
19  
20  import javax.servlet.ServletException  ;
21  import javax.servlet.http.HttpServletRequest  ;
22  import javax.servlet.http.HttpServletResponse  ;
23  import javax.servlet.http.HttpSession  ;
24  
25  /**
26   * Class to enable us to access servlet parameters.
27   * @author Joe Walker [joe at getahead dot ltd dot uk]
28   */
29  public interface WebContext extends ServerContext
30  {
31      /**
32       * Get the script session that represents the currently viewed page in the
33       * same way that an HttpSession represents a cookie.
34       * @return A browser object for this user
35       */
36      ScriptSession getScriptSession();
37  
38      /**
39       * What is the URL of the current page.
40       * This includes 'http://', up to (but not including) '?' or '#'
41       * @return The URL of the current page
42       */
43      String   getCurrentPage();
44  
45      /**
46       * Returns the current session associated with this request, or if the
47       * request does not have a session, creates one.
48       * @return Returns the http session.
49       * @see HttpServletRequest#getSession()
50       */
51      HttpSession   getSession();
52  
53      /**
54       * Returns the current HttpSession associated with this request or, if
55       * there is no current session and create is true, returns a new session.
56       * If create is false and the request has no valid HttpSession, this method
57       * returns null.
58       * @param create false to return null if there's no current session
59       * @return the session associated with this request
60       * @see HttpServletRequest#getSession(boolean)
61       */
62      HttpSession   getSession(boolean create);
63  
64      /**
65       * Accessor for the http request information.
66       * @return Returns the request.
67       */
68      HttpServletRequest   getHttpServletRequest();
69  
70      /**
71       * Accessor for the http response bean.
72       * <p>You can't use this request to directly reply to the response or to add
73       * headers or cookies.
74       * @return Returns the response.
75       */
76      HttpServletResponse   getHttpServletResponse();
77  
78      /**
79       * An attribute used by {@link WebContext#forwardToString(String)} to inform
80       * anyone that wants to know that this is a request from DWR.
81       */
82      public static final String   ATTRIBUTE_DWR = "org.directwebremoting";
83  
84      /**
85       * Forward a request to a given URL and catch the data written to it.
86       * It is possible to distinguish requests that arrive normally and requests
87       * that come from a DWR forwardToString() by the presence of a request
88       * attribute. Before the request is forwarded, DWR will call:
89       * <pre>
90       * request.setAttribute(WebContext.ATTRIBUTE_DWR, Boolean.TRUE);
91       * </pre>
92       * @param url The URL to forward to
93       * @return The text that results from forwarding to the given URL
94       * @throws IOException if the target resource throws this exception
95       * @throws ServletException if the target resource throws this exception
96       * @throws IllegalStateException if the response was already committed
97       */
98      String   forwardToString(String   url) throws ServletException  , IOException  ;
99  
100     /**
101      * For system use only: This method allows the system to fill in the session
102      * id and page id when they are discovered.
103      * @param page The URL of the current page
104      * @param scriptSessionId The session id passed in by the browser
105      */
106     void setCurrentPageInformation(String   page, String   scriptSessionId);
107 }
108
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