001 package edu.nrao.sss.webapp.faces;
002
003 import javax.faces.application.FacesMessage;
004 import javax.faces.context.FacesContext;
005 import javax.faces.event.PhaseEvent;
006 import javax.faces.event.PhaseId;
007 import javax.faces.event.PhaseListener;
008 import javax.servlet.http.HttpServletRequest;
009
010 import org.apache.log4j.Logger;
011
012 import java.util.Enumeration;
013 import java.util.Iterator;
014 import java.util.HashMap;
015 import java.util.Map;
016 import java.util.ArrayList;
017 import java.util.List;
018
019 /**
020 * This class attempts to retain FacesMessages that would other wise be lost
021 * due to a panelDivider being resized. This class only listens to events for
022 * the RENDER_RESPONSE phase. During the afterPhase() method, we cache all
023 * existing FacesMessages in a Map keyed by the associated HttpSession's Id.
024 * During the beforePhase() method, the request parameters are searched for a
025 * parameter name ending in {@code InPercent}. If such a parameter exists and
026 * its value is an integer, then the messages found in the cache are added to
027 * the FacesContext. Either way, the cache is cleared at the end of the
028 * beforePhase() method to make sure we're not holding onto stale
029 * FacesMessages.
030 */
031 public class FacesMessagePhaseListener implements PhaseListener
032 {
033 private static final Logger log = Logger.getLogger(FacesMessagePhaseListener.class);
034
035 private static final String MESSAGES_WITH_NO_CLIENT_ID = "MESSAGES_WITH_NO_CLIENT_ID";
036
037 // Map<sessionid, Map<componentId, List<Messages for component>>>
038 private Map<String, Map<String, List<FacesMessage>>> cache = new HashMap<String, Map<String, List<FacesMessage>>>();
039
040 public PhaseId getPhaseId() { return PhaseId.RENDER_RESPONSE; }
041
042 /**
043 * If the request has a parameter ending in "InPercent" defined to a
044 * non-empty string (an integer to be exact), then add the cached
045 * FacesMessages back to the FacesContext. Either way, empty the cache.
046 */
047 public synchronized void beforePhase(PhaseEvent event)
048 {
049 FacesContext c = event.getFacesContext();
050 HttpServletRequest req = (HttpServletRequest)c.getExternalContext().getRequest();
051
052 for (Object key : req.getParameterMap().keySet())
053 {
054 String name = (String)key;
055 if (name.endsWith("InPercent"))
056 {
057 String val = req.getParameter(name);
058 if (val != null)
059 {
060 try
061 {
062 Integer.parseInt(val);
063 restoreMessagesFromCache(c);
064 break;
065 }
066
067 // Ignore value if it is not a valid integer.
068 catch (NumberFormatException nfe) {}
069 }
070 }
071 }
072
073 clearMessageCache(c);
074 }
075
076 /**
077 * Always caches all FacesMessages for possible later use in the beforePhase
078 * method.
079 */
080 public synchronized void afterPhase(PhaseEvent event)
081 {
082 cacheMessages(event.getFacesContext());
083 }
084
085 /**
086 * Returns the sessionid of the HttpSession associated with {@code c}.
087 */
088 private String getSessionId(FacesContext c)
089 {
090 HttpServletRequest req = (HttpServletRequest)c.getExternalContext().getRequest();
091 return req.getSession().getId();
092 }
093
094 /**
095 * Caches all FacesMessages in {@code c} in our local Map. NOTE: cache for c
096 * is expected to be empty before this is called! If it isn't, duplicate
097 * messages may be added or messages may be overwritten or lost.
098 */
099 private void cacheMessages(FacesContext c)
100 {
101 String sessionIdKey = getSessionId(c);
102
103 // Map<componentId, list of messages for componentId>
104 Map<String, List<FacesMessage>> messages = new HashMap<String, List<FacesMessage>>();
105
106 for (Iterator idIt = c.getClientIdsWithMessages(); idIt.hasNext();)
107 {
108 String clientId = (String)idIt.next();
109 String idKey = clientId;
110
111 if (clientId == null)
112 idKey = MESSAGES_WITH_NO_CLIENT_ID;
113
114 List<FacesMessage> msgsForId = new ArrayList<FacesMessage>();
115 for (Iterator msgIt = c.getMessages(clientId); msgIt.hasNext();)
116 msgsForId.add((FacesMessage)msgIt.next());
117
118 messages.put(idKey, msgsForId);
119 }
120
121 if (cache.put(sessionIdKey, messages)!= null)
122 {
123 // Possible error? do we care?
124 }
125 }
126
127 /**
128 * If there are messages cached for {@code c}, then they are added to {@code c}.
129 * No effort is taken to make sure there are no duplicate messages!
130 */
131 private void restoreMessagesFromCache(FacesContext c)
132 {
133 // Map<componentId, list of messages for componentId>
134 Map<String, List<FacesMessage>> messages = cache.get(getSessionId(c));
135
136 if (messages != null && !messages.isEmpty())
137 {
138 for (String idKey : messages.keySet())
139 {
140 String clientId = idKey;
141 if (idKey == MESSAGES_WITH_NO_CLIENT_ID)
142 clientId = null;
143
144 for (FacesMessage msg : messages.get(idKey))
145 c.addMessage(clientId, msg);
146 }
147 }
148 }
149
150 /**
151 * Clears all cached items related to {@code c}.
152 */
153 private void clearMessageCache(FacesContext c)
154 {
155 cache.remove(getSessionId(c));
156 }
157 }