Re: Confused by java.util.Collections$UnmodifiableMap problem when using Window.Location.getParameterMap() : Source Code Included.

Hi,

I did a small test locally... and I am right: the unmodifiableMap is
not Serializable... at least not in that direction.
A simple fix would be to copy the ParameterMap to a regular HashMap
like this:

new HashMap<String, List<String>>(Window.Location.getParameterMap())

PS: Can you vote for me in stackoverflow ?

David

On Nov 26, 12:41 pm, redboffin <lostlittleal...@googlemail.com> wrote:
> Hello All :-)
>
> I am building a sandpit web application using GWT that is hosted on
> App Engine and displayed within facebook as a canvas app.
>
> I am trying to implement validation, usinghttp://wiki.developers.facebook.com/index.php/User:Google_Web_Toolkit...
> as a guide.
>
> The problem I am encountering is that when I try to use the Map
> returned by Window.Location.getParameterMap() a java.util.Collections
> $UnmodifiableMap problem occurs, even though I'm not modifying the Map
> (at least I don't think I am modifying the Map).
>
> I would be really grateful if someone could take the time to help my
> understand what I am doing wrong here or point out where I should post
> this problem if this forum is not a suitable place to raise this
> problem.
>
> Thank you in advance :-)
>
> Source Code Below.
>
> The onModuleLoad() code within my EntryPoint class is below;
>
> fbValidationService.test(Window.Location.getParameterMap(), new
> AsyncCallback<String>() {
>
>                         public void onFailure(Throwable caught) {
>
>                                 // Show the RPC error message to the user
>
>                                 RootPanel.get("serverResponse").add(new HTML("Remote Procedure
> Call : Test 261109 10:51 - Failure"));
>                                 RootPanel.get("serverResponse").add(new HTML(SERVER_ERROR));
>                                 RootPanel.get("serverResponse").add(new HTML(caught.getMessage
> ()));
>                                 RootPanel.get("serverResponse").add(new HTML("Stack Trace"));
>                                 StackTraceElement[] stackTrace = caught.getStackTrace();
>                                 for(int i = 0 ; i < stackTrace.length ; i++) {
>                                         StackTraceElement element = stackTrace[i];
>                                         RootPanel.get("serverResponse").add(new HTML(element.getFileName
> ()));
>                                         RootPanel.get("serverResponse").add(new HTML(element.getClassName
> ()));
>                                         RootPanel.get("serverResponse").add(new HTML(element.getMethodName
> ()));
>                                         RootPanel.get("serverResponse").add(new HTML(Integer.toString
> (element.getLineNumber())));
>                                 }
>
>                         }
>
>                         public void onSuccess(String result) {
>
>                                 // Show the RPC result to the user
>
>                                 RootPanel.get("serverResponse").add(new HTML("Remote Procedure
> Call : Test - Success"));
>                                 RootPanel.get("serverResponse").add(new HTML(result));
>
>                         }
>
>                 });
>
> The test() method within the RemoteServiceServlet object is below;
>
>         /**
>          * Validation Test
>          * To generate the signature for these arguments:
>          * 1. Remove the fb_sig key and value pair.
>          * 2. Remove the "fb_sig_" prefix from all of the keys.
>          * 3. Sort the array alphabetically by key.
>          * 4. Concatenate all key/value pairs together in the format "k=v".
>          * 5. Append your secret key.
>          * 6. Take the md5 hash of the whole string.
>          * @param fbQueryStringParams
>          * @return String
>          */
>         public String test(Map<String,List<java.lang.String>>
> fbQueryStringParams) {
>
>                 String appSecret = TinyFBClient.APP_SECRET;
>                 String fbSig = fbQueryStringParams.get("fb_sig").get(0);
>                 StringBuilder sb = new StringBuilder();
>                 TreeMap<String,String> sortedMap = new TreeMap<String,String>();
>
>                 // Get a Set view of the Map of query string parameters.
>                 Set<Map.Entry<String,List<java.lang.String>>> mapEntries =
> fbQueryStringParams.entrySet();
>
>                 // Iterate through the Set view, inserting into a SortedMap all
> Map.Entry's
>                 // that do not have a Key value of "fb_sig".
>                 Iterator<Map.Entry<String,List<java.lang.String>>> i =
> mapEntries.iterator();
>                 while(i.hasNext()) {
>
>                         Map.Entry<String,List<java.lang.String>> mapEntry = i.next();
>
>                         if(!mapEntry.getKey().equals("fb_sig")) { // 1. Remove the fb_sig
> key and value pair.
>
>                                 sortedMap.put(mapEntry.getKey(),mapEntry.getValue().get(0)); // 3.
> Sort the array alphabetically by key.
>
>                         }
>
>                 }
>
>                 // Get a Set view of the Map of alphabetically sorted Map.Entry
> objects.
>                 Set<Map.Entry<String,String>> sortedMapEntries = sortedMap.entrySet
> ();
>
>                 // Iterate through the Set view, appending the concatenated key's
> and value's
>                 // to a StringBuilder object.
>                 Iterator<Map.Entry<String,String>> ii = sortedMapEntries.iterator();
>                 while(ii.hasNext()) {
>
>                         Map.Entry<String,String> mapEntry = ii.next();
>
>                         // 4. Concatenate all key/value pairs together in the format "k=v".
>                         sb.append(mapEntry.getKey().replaceAll("fb_sig_","")); // 2. Remove
> the "fb_sig_" prefix from all of the keys.
>                         sb.append("=");
>                         sb.append(mapEntry.getValue());
>
>                 }
>
>                 sb.append(appSecret); // 5. Append your secret key.
>
>                 String md5 = DigestUtils.md5Hex(sb.toString()); // 6. Take the md5
> hash of the whole string.
>
>                 // Build and return an output String for display.
>                 StringBuilder output = new StringBuilder();
>                 output.append("fbSig = "+fbSig);
>                 output.append("<br/>");
>                 output.append("md5 = "+md5);
>                 return output.toString();
>
>         }
>
> The output displayed on the web app (when displayed within facebook)
> is below;
>
> Remote Procedure Call : Test 261109 10:51 - Failure
> An error occurred while attempting to contact the server. Please check
> your network connection and try again.
> java.util.Collections$UnmodifiableMap
> Stack Trace

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