HttpSessionStateMap


1   /*
2    * Copyright (C) 2003  Christian Cryder [christianc@granitepeaks.com]
3    *
4    * This library is free software; you can redistribute it and/or
5    * modify it under the terms of the GNU Lesser General Public
6    * License as published by the Free Software Foundation; either
7    * version 2.1 of the License, or (at your option) any later version.
8    *
9    * This library is distributed in the hope that it will be useful,
10   * but WITHOUT ANY WARRANTY; without even the implied warranty of
11   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12   * Lesser General Public License for more details.
13   *
14   * You should have received a copy of the GNU Lesser General Public
15   * License along with this library; if not, write to the Free Software
16   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
17   *
18   * $Id: HttpSessionStateMap.java,v 1.7 2004/02/01 05:16:28 christianc Exp $
19   */
20  package org.enhydra.barracuda.plankton.data;
21  
22  import java.io.*;
23  import java.util.*;
24  import javax.servlet.*;
25  import javax.servlet.http.*;
26  
27  /**
28   * The implementation provides a StateMap bridge to a HttpSession
29   * object. By this, we mean that this class allows you to treat an
30   * HttpSession as a StateMap. Unlike the HttpSession, this class 
31   * will handle null keys, values.
32   */
33  public class HttpSessionStateMap implements StateMap {
34  
35      //private vars
36      protected HttpSession session = null;
37      private String   NULL = "~Null~";                    
38      
39      /**
40       * Public constructor.
41       *
42       * @param isession the underlying servlet session structure
43       */    
44      public HttpSessionStateMap(HttpSession isession) {
45          session = isession;
46      }
47      
48      /**
49       * set a property in this StateMap
50       *
51       * @param key the key object
52       * @param val the value object
53       */    
54      public void putState(Object   key, Object   val) {
55          if (key==null) key = NULL;
56          if (val==null) val = NULL;
57          session.setAttribute(key.toString(),val);
58      }
59      
60      /**
61       * get a property in this StateMap
62       *
63       * @param key the key object
64       * @return the value for the given key
65       */    
66      public Object   getState(Object   key) {
67          if (key==null) key = NULL;
68          Object   val = session.getAttribute(key.toString());
69          return ((val==null || val.equals(NULL)) ? null : val);
70      }
71      
72      /**
73       * remove a property in this StateMap. This function was expanded in csc_082103_1 to
74       * support the notion of wildcarding, allowing you to remove multiple keys in one fell
75       * swoop. Basically, if the key is a String, which ends with an '*', then any keys that
76       * start with that string will be removed (and in this case, the method returns a Map of
77       * key/val pairs that got removed, rather than a single object that got removed). This 
78       * approach is not quite as flexible as using regular expressions, but that would make us 
79       * dependent on jdk1.4 (so we won't go there for now). Note that this class backs the 
80       * ObjectRepository data structures, so this functionality applies there as well.
81       *
82       * @param key the key object
83       * @return the object which was removed
84       */    
85      public Object   removeState(Object   key) {
86  //csc_082103_1_start 
87          try {   //csc_011904_2
88              //remove all keys that match
89              if (key!=null && (key instanceof String  ) && ((String  ) key).endsWith("*")) {
90                  Map removed = new HashMap();
91                  String   keystr = (String  ) key;
92                  String   targetstr = keystr.substring(0,keystr.length()-1);
93                  List keys = getStateKeys();
94                  Iterator it = keys.iterator();
95                  while (it.hasNext()) {
96                      Object   okey = it.next();
97                      if ((okey instanceof String  ) && ((String  ) okey).startsWith(targetstr)) {
98                          Object   oval = session.getAttribute(okey.toString());
99                          removed.put(okey, oval);
100                         session.removeAttribute(okey.toString());
101                     }
102                 }
103                 return (removed.size()>0 ? removed : null);        
104             } else {
105     //csc_082103_1_end
106                 if (key==null) key = NULL;
107                 Object   val = session.getAttribute(key.toString());
108                 session.removeAttribute(key.toString());
109         //csc_040203.1        return (val.equals(NULL) ? null : val);
110                 return ((val==null || val.equals(NULL)) ? null : val);  //csc_040203.1
111             }
112         
113         //this occasionally happens if the session expires as you are in the process of 
114         //taking something out of it...in such a case, just catch the error and return null
115         } catch (NullPointerException   e) {  //csc_011904_2 - added
116             return null;        
117         }
118     }
119     
120     /**
121      * get a List of the keys for this StateMap (implementation
122      * is an ArrayList)
123      *
124      * @return a List the keys for this StateMap
125      */    
126     public List getStateKeys() {
127         Enumeration e = session.getAttributeNames();
128         List list = new ArrayList();
129         while (e.hasMoreElements())    {
130             list.add(e.nextElement());
131         }        
132         return list;
133     }
134     
135     /**
136      * get a copy of the underlying Map (in this case, we
137      * map all the attributes of the HttpSession structure
138      * into a Map and return that)
139      *
140      * @return a copy of the underlying state Map
141      */    
142     public Map getStateValues() {
143         Map map = new HashMap();
144         List keys = getStateKeys();
145         Iterator it = keys.iterator();
146         while (it.hasNext()) {
147             Object   key = it.next();
148             Object   val = session.getAttribute(key.toString());
149             map.put(key,val);            
150         }
151         return map;        
152     }
153 
154     //csc_052803_2 - added
155     /**
156      * clear all state information
157      */
158     public void clearState() {
159         List keys = getStateKeys();
160         Iterator it = keys.iterator();
161         while (it.hasNext()) {
162             Object   key = it.next();
163             removeState(key);
164         }
165     }
166 
167     /**
168      * get a reference to the underlying HttpSession
169      *
170      * @return a reference to the underlying HttpSession
171      */    
172     public HttpSession getSession() {
173         return session;
174     }
175 }
176
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