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Java > Open Source Codes > com > jcorporate > expresso > core > jsdkapi > GenericSession


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64
65 /**
66  * GenericSession.java
67  *
68  * Copyright 2000, 2001 Jcorporate Ltd.
69  */
70 package com.jcorporate.expresso.core.jsdkapi;
71
72 import com.jcorporate.expresso.core.misc.ConfigManager;
73 import com.jcorporate.expresso.core.misc.SerializableString;
74 import com.jcorporate.expresso.kernel.util.ClassLocator;
75
76 import javax.servlet.ServletException JavaDoc;
77 import javax.servlet.http.HttpServletRequest JavaDoc;
78 import java.io.Serializable JavaDoc;
79 import java.util.Enumeration JavaDoc;
80
81
82 /**
83  * Different servlet API's have slightly different methods
84  * for putting & getting attributes into the session, so we
85  * have a method here for cross-API access to the session,
86  * and methods that automatically "wrap" string values
87  * stored in the session in SerializableString, so the web-apps
88  * can be distributed & session shared by appropriate app servers
89  *
90  * @author Mike Nash
91  */
92 public class GenericSession {
93
94     private GenericSession() {
95     } // no instantiations
96
97     // This is used for optimization. The actual session is loaded
98 // only once, if this flag indicates that it hasn't been so far
99 private static boolean classLoaded = false;
100
101     // This is the actual dispatcher that is filled in at runtime
102 // There are no compile time dependencies because instead of using
103 // the real JSDK-2.0 or JSDK-2.1 implementation classes
104 // we simply use a generic interface here.
105 private static APIAwareSession mySession = null;
106
107     // The fully-qualified name of this class
108 private static final java.lang.String JavaDoc thisClass = GenericSession.class.getName();
109
110     // This is the name of the class that implements the Servlet API 2.2 Session
111 private static final java.lang.String JavaDoc ServletAPI2_2Session =
112             "com.jcorporate.expresso.core.jsdkapi.ServletAPI2_2Session";
113
114     /**
115      * Store a String (wrapped in a SerializableString) in the session
116      *
117      * @param req The HttpServletRequest object
118      * @param code the attribute code
119      * @param value the attribute value
120      */
121     public synchronized static void setAttribute(HttpServletRequest JavaDoc req,
122                                                  String JavaDoc code, String JavaDoc value)
123             throws ServletException JavaDoc {
124
125         // Name of this method, used for debug-printing
126 SerializableString ss = new SerializableString(value);
127
128         // Check and load the APIAwareSession class if necessary
129 if (classLoaded == false) {
130             loadClass();
131         }
132
133         // Let the APIAwareSession do the setAttribute operation
134 mySession.setAttribute(req, code, ss);
135     } /* setAttribute(HttpServletRequest, String, STring) */
136
137
138     /**
139      * Return a string stored in the session, unwrapping it from the
140      * SerializableString it was stored in
141      *
142      * @param req the HttpServletRequest
143      * @param code the attribute key
144      * @return java.lang.String
145      * @throws ServletException upon error
146      */
147     public synchronized static String JavaDoc getAttributeString(HttpServletRequest JavaDoc req,
148                                                          String JavaDoc code)
149             throws ServletException JavaDoc {
150
151         // Check and load the APIAwareSession class if necessary
152 if (classLoaded == false) {
153             loadClass();
154         }
155
156         Object JavaDoc o = mySession.getAttribute(req, code);
157
158         if (o == null) {
159             return "";
160         }
161
162         return o.toString();
163
164         /* if (o instanceof SerializableString) {
165
166 SerializableString ss = (SerializableString) o;
167
168 return StringUtil.notNull(ss.toString());
169
170 } else {
171
172 throw new ServletException(myName + ":Object stored in session with key '"
173
174 + code + "' was not a SerializableString - it was a '"
175
176 + o.getClass().getName() + "' with value '" + o.toString() + "'");
177
178 } */
179     } /* getAttributeString(HttpServletRequest, String) */
180
181
182     /**
183      * Retrieve any other object
184      *
185      * @param req The servlet request object
186      * @param code the attribute key
187      * @return the attribute value object
188      * @throws ServletException upon error
189      */
190     public static Object JavaDoc getAttribute(HttpServletRequest JavaDoc req, String JavaDoc code)
191             throws ServletException JavaDoc {
192         if (classLoaded == false) {
193             loadClass();
194         }
195
196         return mySession.getAttribute(req, code);
197     } /* getAttribute(HttpServletRequest, String) */
198
199
200     /**
201      * Invalidate the session
202      *
203      * @param req the servlet request object
204      * @throws ServletException upon error
205      */
206     public synchronized static void invalidate(HttpServletRequest JavaDoc req)
207             throws ServletException JavaDoc {
208
209         // Check and load the APIAwareSession class if necessary
210 if (classLoaded == false) {
211             loadClass();
212         }
213
214         // Let the APIAwareSession do the setAttribute operation
215 mySession.invalidate(req);
216     } /* invalidate(HttpServletRequest) */
217
218
219     /**
220      * Store any Serializable object in the session
221      *
222      * @param req the ServletRequest object
223      * @param code the attirbute code
224      * @param s the serializable value to save to the session
225      * @throws ServletException upon error
226      */
227     public synchronized static void setAttribute(HttpServletRequest JavaDoc req,
228                                                  String JavaDoc code, Serializable JavaDoc s)
229             throws ServletException JavaDoc {
230
231         // Check and load the APIAwareSession class if necessary
232 if (classLoaded == false) {
233             loadClass();
234         }
235
236         // Let the APIAwareSession do the setAttribute operation
237 mySession.setAttribute(req, code, s);
238     } /* setAttribute(HttpServletRequest, String, Serializable) */
239
240
241     /**
242      * Remove an attribute from the session
243      *
244      * @param req the servletrequest object
245      * @param code the attribute key
246      * @throws ServletException upon error
247      */
248     public synchronized static void removeAttribute(HttpServletRequest JavaDoc req,
249                                                     String JavaDoc code)
250             throws ServletException JavaDoc {
251
252         // Check and load the APIAwareSession class if necessary
253 if (classLoaded == false) {
254             loadClass();
255         }
256
257         // Let the APIAwareSession do the removeAttribute operation
258 mySession.removeAttribute(req, code);
259     } /* removeAttribute(HttpServletRequest, String) */
260
261
262     /**
263      * Retrieve all attribute names
264      *
265      * @param req the servlet request object
266      * @return an Enumeration of all the names in the session
267      * @throws ServletException upon error
268      */
269     public static Enumeration JavaDoc getAttributeNames(HttpServletRequest JavaDoc req)
270             throws ServletException JavaDoc {
271
272         // Check and load the APIAwareSession class if necessary
273 if (classLoaded == false) {
274             loadClass();
275         }
276
277         // Let the APIAwareSession do the removeAttribute operation
278 return mySession.getAttributeNames(req);
279     } /* getAttributeNames(HttpServletRequest) */
280
281
282     /**
283      * Retrieve the session id
284      *
285      * @param req the servlet request
286      * @return the session id string
287      * @throws ServletException upon error
288      */
289     public static String JavaDoc getId(HttpServletRequest JavaDoc req)
290             throws ServletException JavaDoc {
291
292         // Check and load the APIAwareSession class if necessary
293 if (classLoaded == false) {
294             loadClass();
295         }
296
297         // Let the APIAwareSession do the removeAttribute operation
298 return mySession.getId(req);
299     } /* getId(HttpServletRequest) */
300
301
302     /**
303      * Retrieve the context path
304      *
305      * @param req the servlet request object
306      * @return the string for the servlet context path
307      * @throws ServletException upon error
308      */
309     public synchronized static String JavaDoc getContextPath(HttpServletRequest JavaDoc req)
310             throws ServletException JavaDoc {
311
312
313         // Check and load the APIAwareSession class if necessary
314 if (classLoaded == false) {
315             loadClass();
316         }
317
318         // Let the APIAwareSession do the getContextPath operation
319 return mySession.getContextPath(req);
320     } /* getContextPath(HttpServletRequest) */
321
322
323     /**
324      * This method dynamically loads the correct APIAwareSession
325      * class based on whether the user specified Servlet API-2.0
326      * compatibility or not. Currently the switch is pretty "dumb".
327      * If the user explicitly specifies Servlet API 2.0 compatibilty
328      * by using a config parameter ("servletAPI=2_0"), then the
329      * Servlet API 2.0 compatible RequestSession is loaded.
330      */
331     private static void loadClass()
332             throws ServletException JavaDoc {
333
334         // The name of this class, used for debug-printing
335 String JavaDoc myName = thisClass + "loadClass()";
336
337         try {
338             String JavaDoc apiVersion = ConfigManager.getServletAPIVersion();
339             Class JavaDoc c = null;
340
341             // if (apiVersion.equals("2_2")) {
342 c = ClassLocator.loadClass(ServletAPI2_2Session);
343
344             mySession = (APIAwareSession) c.newInstance();
345
346             // Handle the various problems that might happen!
347 } catch (ClassNotFoundException JavaDoc cn) {
348             throw new ServletException JavaDoc(myName +
349                     ":APIAwareSession class not found:" +
350                     cn.getMessage());
351         } catch (InstantiationException JavaDoc ie) {
352             throw new ServletException JavaDoc(myName +
353                     ":APIAwareSession class cannot be instantiated:" +
354                     ie.getMessage());
355         } catch (IllegalAccessException JavaDoc iae) {
356             throw new ServletException JavaDoc(myName +
357                     ":Illegal access loading APIAwareSession object:" +
358                     iae.getMessage());
359         }
360
361         // We only want to go through this once!
362 classLoaded = true;
363     } /* loadClass() */
364
365
366 } /* GenericSession */
367
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