Connection


1   /* 
2    * This file is part of the Echo Web Application Framework (hereinafter "Echo").
3    * Copyright (C) 2002-2005 NextApp, Inc.
4    *
5    * Version: MPL 1.1/GPL 2.0/LGPL 2.1
6    *
7    * The contents of this file are subject to the Mozilla Public License Version
8    * 1.1 (the "License"); you may not use this file except in compliance with
9    * the License. You may obtain a copy of the License at
10   * http://www.mozilla.org/MPL/
11   *
12   * Software distributed under the License is distributed on an "AS IS" basis,
13   * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
14   * for the specific language governing rights and limitations under the
15   * License.
16   *
17   * Alternatively, the contents of this file may be used under the terms of
18   * either the GNU General Public License Version 2 or later (the "GPL"), or
19   * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
20   * in which case the provisions of the GPL or the LGPL are applicable instead
21   * of those above. If you wish to allow use of your version of this file only
22   * under the terms of either the GPL or the LGPL, and not to allow others to
23   * use your version of this file under the terms of the MPL, indicate your
24   * decision by deleting the provisions above and replace them with the notice
25   * and other provisions required by the GPL or the LGPL. If you do not delete
26   * the provisions above, a recipient may use your version of this file under
27   * the terms of any one of the MPL, the GPL or the LGPL.
28   */
29  
30  package nextapp.echo2.webrender;
31  
32  import java.io.IOException  ;
33  import java.io.OutputStream  ;
34  import java.io.PrintWriter  ;
35  import java.util.HashMap  ;
36  import java.util.Map  ;
37  
38  import javax.servlet.ServletException  ;
39  import javax.servlet.http.HttpServletRequest  ;
40  import javax.servlet.http.HttpServletResponse  ;
41  import javax.servlet.http.HttpSession  ;
42  
43  /**
44   * A representation of a connection to the server by the client, encapsulating
45   * the servlet request and response objects, and providing access to the
46   * relevant application instance.
47   * <code>Connection</code>s also manage the life-cycle of 
48   * <code>UserInstance</code>s within the <code>HttpSession</code>.
49   */
50  public class Connection {
51  
52      /**
53       * Prefix to use for user instance <code>HttpSession</code> keys.
54       */
55      private static final String   USER_INSTANCE_SESSION_KEY_PREFIX = "Echo2UserInstance";
56  
57      private HttpServletRequest   request;
58      private HttpServletResponse   response;
59      private WebRenderServlet servlet;
60      private UserInstance userInstance;
61      private Map   propertyMap;
62      
63      /**
64       * Creates a <code>connection</code> object that will handle the given 
65       * request and response.  The <code>UserInstance</code> will be acquired from the session 
66       * if one exists.  A session will NOT be created if one does not exist.
67       *
68       * @param servlet the <code>WebRenderServlet</code> generating the connection
69       * @param request the HTTP request object that was passed to the servlet
70       * @param response the HTTP response object that was passed to the servlet
71       */
72      Connection(WebRenderServlet servlet, HttpServletRequest   request, HttpServletResponse   response) throws IOException  ,
73              ServletException   {
74          super();
75  
76          this.servlet = servlet;
77          this.request = request;
78          this.response = response;
79  
80          // Configure connection for Multipart Request if required.
81          String   contentType = request.getContentType();
82          if (contentType != null && contentType.startsWith(ContentType.MULTIPART_FORM_DATA.getMimeType())) {
83              if (WebRenderServlet.getMultipartRequestWrapper() == null) {
84                  throw new WebRenderServletException("MultipartRequestWrapper was never set and client made an HTTP request "
85                          + "encoded as multipart/form-data.");
86              }
87              this.request = WebRenderServlet.getMultipartRequestWrapper().getWrappedRequest(request);
88          }
89  
90          HttpSession   session = request.getSession(false);
91          if (session != null) {
92              userInstance = (UserInstance) session.getAttribute(getSessionKey());
93          }
94      }
95  
96      /**
97       * Disposes of the <code>UserInstance</code> associated with this 
98       * <code>Connection</code>.
99       */
100     void disposeUserInstance() {
101         HttpSession   session = request.getSession(false);
102         if (session != null) {
103             getUserInstance().setServletUri(null);
104             session.removeAttribute(getSessionKey());
105         }
106     }
107 
108     /**
109      * Returns the <code>OutputStream</code> object that may be used to 
110      * generate a response.  This method may be called once.  If it is called, 
111      * the getPrintWriter() method may not be called.  This method wraps a 
112      * call to <code>HttpServletResponse.getOutputStream()</code>.  The 
113      * <code>OutputStream</code> will be closed by the servlet container.
114      *
115      * @return the <code>OutputStream</code> object that may be used to 
116      *         generate a response to the client
117      */
118     public OutputStream   getOutputStream() {
119         try {
120             return response.getOutputStream();
121         } catch (IOException   ex) {
122             throw new WebRenderServletException("Unable to get PrintWriter.", ex);
123         }
124     }
125     
126     /**
127      * Returns a property from the <code>Connection</code>-persistent 
128      * property map.  (Properties are disposed of when <code>Connection</code>
129      * has completed). 
130      * 
131      * @param key the property key (for namespacing purposes, keys should 
132      *        be prefaced with the full class name of the object setting the
133      *        property)
134      * @return the property value
135      */
136     public Object   getProperty(String   key) {
137         return propertyMap == null ? null : propertyMap.get(key);
138     }
139 
140     /**
141      * Returns the <code>HttpServletRequest</code> wrapped by this 
142      * <code>Connection</code>.
143      *
144      * @return the <code>HttpServletRequest</code> wrapped by this 
145      *         <code>Connection</code>
146      */
147     public HttpServletRequest   getRequest() {
148         return request;
149     }
150 
151     /**
152      * Returns the <code>HttpServletResponse</code> wrapped by this 
153      * <code>Connection</code>.
154      *
155      * @return the <code>HttpServletResponse</code> wrapped by this 
156      *         <code>Connection</code>
157      */
158     public HttpServletResponse   getResponse() {
159         return response;
160     }
161 
162     /**
163      * Determines the <code>HttpSession</code> key value in which the
164      * associated <code>UserInstance</code> should be stored.
165      * 
166      * @return the <code>HttpSession</code> key
167      */
168     private String   getSessionKey() {
169         return USER_INSTANCE_SESSION_KEY_PREFIX + ":" + servlet.getServletName();
170     }
171 
172     /**
173      * Returns the <code>WebRenderServlet</code> wrapped by this 
174      * <code>Connection</code>.
175      *
176      * @return the <code>WebRenderServlet</code> wrapped by this 
177      *         <code>Connection</code>
178      */
179     public WebRenderServlet getServlet() {
180         return servlet;
181     }
182 
183     /**
184      * Returns the <code>UserInstance</code> associated with 
185      * this connection.  If the session has not been initialized, null is 
186      * returned.
187      *
188      * @return the <code>UserInstance</code> associated with  
189      *         this connection
190      */
191     public UserInstance getUserInstance() {
192         return userInstance;
193     }
194 
195     /**
196      * Returns the <code>PrintWriter</code> object that may be used to 
197      * generate a response.  This method may be called once.  If it is called, 
198      * the getOuputStream() method may not be called.  This method wraps a 
199      * call to <code>HttpServletResponse.getWriter()</code>.  The 
200      * <code>PrintWriter</code> will be closed by the servlet container.
201      *
202      * @return the <code>PrintWriter</code> object that may be used to 
203      *         generate a response to the client
204      */
205     public PrintWriter   getWriter() {
206         try {
207             return response.getWriter();
208         } catch (IOException   ex) {
209             throw new WebRenderServletException("Unable to get PrintWriter.", ex);
210         }
211     }
212 
213     /**
214      * Initializes the state of a new <code>UserInstance</code> and associates
215      * it with this <code>Connection</code> and the underlying
216      * <code>HttpSession</code>
217      * 
218      * @param userInstance the <code>UserInstance</code>
219      */
220     void initUserInstance(UserInstance userInstance) {
221         this.userInstance = userInstance;
222         userInstance.setServletUri(request.getRequestURI());
223         HttpSession   session = request.getSession(true);
224         session.setAttribute(getSessionKey(), userInstance);
225     }
226 
227     /**
228      * Sets the content type of the response.
229      * This method will automatically append a character encoding to
230      * non-binary content types.
231      * 
232      * @param contentType the content type of the response
233      */
234     public void setContentType(ContentType contentType) {
235         UserInstance userInstance = getUserInstance();
236         if (contentType.isBinary() || userInstance == null) {
237             response.setContentType(contentType.getMimeType());
238         } else {
239             response.setContentType(contentType.getMimeType() + "; charset=" + userInstance.getCharacterEncoding());
240         }
241     }
242     
243     /**
244      * Sets a property inthe <code>Connection</code>-persistent 
245      * property map.  (Properties are disposed of when <code>Connection</code>
246      * has completed). 
247      * 
248      * @param key the property key (for namespacing purposes, keys should 
249      *        be prefaced with the full class name of the object setting the
250      *        property)
251      * @param value the new property value
252      */
253     public void setProperty(String   key, Object   value) {
254         if (propertyMap == null) {
255             propertyMap = new HashMap  ();
256         }
257         propertyMap.put(key, value);
258     }
259 }
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