Custom Java exception
A Simple Java exception that adds a new field called customDetails (via a Bean Property)

public class myCustomException extends RuntimeException {

  private static final long serialVersionUID = 1L;
  private String details;
  public CampaignSaveException(String arg0) {
    super(arg0);
    details = arg0;
  }

  public String getCustomDetails(){
    return details;
  }
}

When Java throws this exception during a remote call (i.e..)

  throw new myCustomException ("Details for the error message");

I can use this method to identify that this is in fact a myCustomException exception by looking for properties relevant to that class. This gives me an option to do some conditional logic when handling exceptions.

Note the usage of the “Bean property” where getCustomDetails() is set in the Java class but referenced in the front end as errorMessage.rootCause.customDetails.

private function onSaveError(event:FaultEvent):void
{
  var errorMessage:ErrorMessage = event.message as ErrorMessage;
  if(errorMessage.rootCause.customDetails != null)
    Alert.show(errorMessage.rootCause.customDetails, "", Alert.OK);
  else{
    Alert.show("Generic Error Message", "", Alert.OK);
  }
}

I believe there are more advanced methods than looking for a “bean property” (maybe casting?) but as the title suggests this is a quick and dirty example. Looking over the BlazeDS documentation

http://livedocs.adobe.com/blazeds/1/blazeds_devguide/help.html?content=serialize_data_2.html.

It doesn’t look like BlazeDS will map Custom Java Exceptions to Flex Exceptions .. So i think there’s always going to be a little bit of hackery to any implementation of passing and handling exceptions between Java and Flex.

When compiling large Flex apps via ant on crappy machines (like the one my job provides me) You may get a Java out of memory heap error.

I got past this by doing the following

In Eclipse
1. Open up the ant “run as” dialog box
2. go the JVM tab and add the following argument to the JVM arguments section “-Xmx512M”

In Ant from the command line
1. set ANT_OPTS= -Xmx512M

set ANT_OPTS=-Xmx512M; export ANT_OPTS

Hope this helps

When a Java method throws an exception (see example)

public static boolean someMethod(boolean myVar) throws Exception
{
  if(myVar)
    throw new Exception("A Simple Exception");
  else
   return true;
}

To handle the Exception gracefully (i.e. strip out the stack trace and display just the Error message)

import mx.messaging.messages.ErrorMessage;
....
private function onDBErrorError(event:FaultEvent):void
{
  var msg:ErrorMessage = event.message as ErrorMessage;
  Alert.show(msg.rootCause.message);
}

Hope this helps..

Steps to install.
Note: This is based off my machines setup Apache 2.2.14, Tomcat 6, Windows 7 64 Bit, Mod JK 1.2.28

1. Download Apache webserver, Install it and verify it is running see “http://httpd.apache.org/” for more information.

2. Download Tomcat, Install it and verify it is running. See “http://tomcat.apache.org/” for more information

3. Download the Apache Tomcat Connector and copy it to [APACHE_ROOT]/modules. See http://tomcat.apache.org/connectors-doc for more information.

I was able to download the MOD_JK here http://apache.multihomed.net/tomcat/tomcat-connectors/jk/binaries/win32/jk-1.2.28/

4. Create a “workers.properties” file and place it at [TOMCAT_ROOT]/conf/jk

AJP13 worker is the preferred worker type that JK uses for communication between web server and Tomcat. Here is a simple implementation of the workers.properties file

worker.list=worker1
worker.worker1.type=ajp13
worker.worker1.host=localhost
worker.worker1.port=8009

5. Edit the Apache Configuration file [APACHE_ROOT]/conf/httpd.conf in the following way

LoadModule jk_module /modules/mod_jk-1.2.28-httpd-2.2.3.so
Include "[PATH_TO_TOMCAT]/conf/auto/mod_jk.conf"

6. Edit Server.xml in [TOMCAT_ROOT]/conf in the following manner.

Under the <Server> node add this

<Listener className = "org.apache.jk.config.ApacheConfig"
workersConfig="conf/workers.properties"
mod_Jk="[PATH_TO_APACHE]/modules/mod_jk.so"
jkLog="logs/mod_jk.log" jkDebug="info" noRoot="false"/>

Under the <Engine> node add this

Restart Tomcat.. You should see a new file [TOMCAT_ROOT]/conf/auto/mod_jk.conf

Restart Apache.. you should be good

Which means the following code snippet does nothing..

(event.target as LinkButton).setStyle("backgroundColor", "#ff0000");

In my case the LinkButton took up the entire space of a GridItem so I was able to set the backgroundColor of the parent and that worked fine for me.

var gridItemRef:GridItem = (event.target as LinkButton).parent as GridItem;
gridItemRef.setStyle("backgroundColor", "#ff0000");

Another method to support a background Color for a LinkButton would be to wrap it in a canvas, but I do not like the added overhead for the canvas.  Skinning may also provide a solution but it just wasn’t necessary in my case.

I wonder what was Adobe’s thought process behind not allowing the background color to be edited?

Placing “javascript:void(0)” in the href portion of the a tag just doesn’t work for Internet explorer version 6.. A common scripting technique that works fine in almost every other browser looks like the following

<a href=”javascript:void(0)” onclick=”myFunction()”>some link</a>

Internet Explorer 6 doesnt support this.. instead try this.

<a href="#" onclick="myFunction();return false;">some link</a>

Google announces a “Test” phone for development purposes that will be released to employees only.

Some people like Motley Fool take this announcement for what it is, and believe there will NOT be a GPhone available to the public in the near future. Others, like the Wall Street Journal, are announcing it will be available to the public very soon.

I am hoping for the latter and that the $200 Nexus One unconfirmed rumor is true. Rumored specs seem to indicate a powerful processor (Qualcomm Snapdragon 1 GHz ARM CPU)  in the device so I am going to guess that the price tag wont be that low. Another article refers to a $500 price tag, which is more likely (if the release is even true).

But one thing is for sure there is alot of buzz out there about this.

A $200 GPhone with no cell service is a pretty tempting offer for someone like me to treat as a development product.  A $500 one.. probably not…

I tried a few suggested work arounds utilizing Pattern and Matcher from java.util.regex but it didn’t work correctly for me on the first few tries. The quick fix for me was to download the Apache commons Lang library, add it to my project and utilize the StringUtils class to perform the string replacement.

here is a quick code blurb demonstrating the StringUtils.replace method.

import org.apache.commons.lang.StringUtils;
..
String XMLDeclaration = "<?xml version=\"1.0\" encoding=\"utf-8\"?>";
soapResp = call.getResponseMessage().getSOAPPartAsString(); // recieving a SoapMessage and I want to remove the XML version declaration
soapResp = org.apache.commons.lang.StringUtils.replace(soapResp, XMLDeclaration, "");
out.println(XMLDeclaration);
out.println("");
out.print(soapResp);
out.println("");

The Apache commons Lang library contains a ton of useful utilities click here for the User guide

http://picasaweb.google.com/davetii/TheBirthOfMaryPenelopeTurner

Recently I came across a scenario where I needed a reference to an HTTPServletRequest object but it was not readily available due to prior architectural decisions. When I say “architectural decisions” I use the term loosely the architecture I was supporting was pretty much a disaster with too many contributing factors to mention but the application has survived for years and is still in use today.

The application is a Flex 1.5 app (yes there are some still out in the Wild) there were pieces of code that required a reference to the HttpServletRequest instance. Often this reference was required from within a Remote Object call so the HttpServletRequest object was not readily available.

The following code sample provided a reference to the existing HttpServletRequest. This app contained code that made back end calls from Flex 1.5 as well as Flex 3 so it handled both instances.

... class named RequestManager
public static HttpServletRequest getHttpRequest() throws Exception
  {
    Class cls;
    try{
      cls = Class.forName("flex.messaging.FlexContext");
    }catch(Exception e){
      cls = Class.forName("flashgateway.Gateway");
    }
     Method meth = cls.getMethod("getHttpRequest", new Class[0]);
     Object retobj = meth.invoke(null);
     if ( retobj == null )
     {
       cls = Class.forName("flashgateway.Gateway");
       meth = cls.getMethod("getHttpRequest", new Class[0]);
       retobj = meth.invoke(null);
     }
     HttpServletRequest req = (HttpServletRequest) retobj;
     return req;
  }

Specifically what this was used for was the management of Session variables. A session Manager class was utilizing the above-mentioned method to get a reference to the existing Servlet Request object. The code in the SessionManager class that utilized this method looked like this.

...
HttpServletRequest req = RequestManager.getHttpRequest();
return req.getSession().getAttribute("MYSessionKey").toString();

This technique worked fine when making Flex Remote Calls but when a Servlet was introduced that needed to utilize the same method calls there was a problem gaining a reference to the HttpServletRequest. Intermediary method calls that existed elsewhere in the code did not contain an argument of HttpServletRequest they utilized the RequestManager to gain this access. This posed a problem when the Servlet wanted to make the method calls that the Remote Object calls relied upon.

So how can the methods called by the Servlet get a reference to the HttpServletRequest?

There where a few possibilities

I was able to reference the source for Adobe’s FlexContext class to see how they did it.

The solution was surprisingly simple.. utilizing the ThreadLocal class.

Here is a quick run down of what i did

1. Define a static class that represents a reference to the HttpServletRequest. This class will be populated by the Servlet.

package dtii.util;
import javax.servlet.http.HttpServletRequest;
public class MyRequest
{
  private static ThreadLocal requests = new ThreadLocal();
  public static void setRequest(HttpServletRequest req) {
     requests.set(req);
  }

  public static HttpServletRequest getRequest() {
    return requests.get();
  }

  public static void removeRequest(){
    requests.remove();
  }
}

2. Edit the RequestManager to look for this class. Feel free to implement in a safer way..

... RequestManager
public static HttpServletRequest getHttpRequest() throws Exception
{
  Class cls;
  try{
    cls = Class.forName("flex.messaging.FlexContext");
  }catch(Exception e){
    cls = Class.forName("flashgateway.Gateway");
  }

  Method meth = cls.getMethod("getHttpRequest", new Class[0]);
  Object retobj = meth.invoke(null);
	if ( retobj == null )
  {
    cls = Class.forName("flashgateway.Gateway");
    meth = cls.getMethod("getHttpRequest", new Class[0]);
    retobj = meth.invoke(null);
  }
  if ( retobj == null )
  {
    retobj = (HttpServletRequest) MyRequest.getRequest();
  }
   HttpServletRequest req = (HttpServletRequest) retobj;
   return req;
}

3. In the Executing Servlet define the Class at the begining and than remove it at the end

import dtii.util.MyRequest;
.. some servlet

public void doGet (HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException
{
	MyRequest.setRequest(req);
	SomeMethod(.. );
	MyRequest.removeRequest();
}

This technique worked well for what i needed.. its not pretty but it worked.

Would love to hear a suggestion on a better method.