programming panda

To map the URL root to certain welcome file, we normally just specify the welcome-file in the web.xml like this

index.html
index.jsp

What this means is, if in a directory without specifying any file name, the web application will first look for index.html and then index.jsp.

Now add struts framework into the picture, default struts extension for 1 and 2 is *.do and *.action respectively.

There are 2 ways of making our application pointing to the special struts action.

#1: Meta redirect
You can keep index.html or index.jsp as welcome-file and what you need to do is put a meta refresh in these index files

Struts 1

meta equiv="refresh" content="0;URL=/homepage.do"

Struts 2

meta equiv="refresh" content="0;URL=/homepage.action"

But the downside of this is - whatever action name you use would appear on the browser. (i.e. www.mydomain.com always appear as www.mydomain.com/homepage.action even user types in www.mydomain.com)

#2: Change welcome-file and add dummy place holder file

The second way (or better way) of fixing the struts action mapping to the URL root is to update the welcome-file list.

Struts 1

homepage.do

Struts 2

homepage.action

And then in the WebContent Root, add a dummy file (e.g. in Struts 2 you need an empty file homepage.action)*This step is important, without the empty dummy file, it won't work, at least in Tomcat*

Now when you hit http://www.mydomain.com your application will hit the homepage.action directly without adding the homepage.action after your url.

GAE(Google App Engine) is a very high security environment, which google limits you in everything. In order to setup your struts 2 on GAE properly, you will need to change the OgnlRuntime security manager.

This is the error you will get on browser

HTTP ERROR: 404

result 'null' not found
RequestURI=/

And on your log

Jul 20, 2009 3:37:20 AM com.opensymphony.xwork2.util.logging.commons.CommonsLogger error
SEVERE: Unable to set parameter [location] in result of type [org.apache.struts2.dispatcher.ServletDispatcherResult]
Caught OgnlException while setting property 'location' on type 'org.apache.struts2.dispatcher.ServletDispatcherResult'. - Class: ognl.OgnlRuntime
File: OgnlRuntime.java
Method: invokeMethod
Line: 508 - ognl/OgnlRuntime.java:508:-1
 at com.opensymphony.xwork2.ognl.OgnlUtil.internalSetProperty(OgnlUtil.java:392)
 at com.opensymphony.xwork2.ognl.OgnlUtil.setProperty(OgnlUtil.java:143)
 at com.opensymphony.xwork2.ognl.OgnlReflectionProvider.setProperty(OgnlReflectionProvider.java:91)
...
...

What you have to do to fix this problem is to add a listener to set the security manager to null.

Listener:

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.http.HttpSessionAttributeListener;
import javax.servlet.http.HttpSessionBindingEvent;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;

import ognl.OgnlRuntime;

public class ONGLFixListener  implements ServletContextListener, HttpSessionListener, HttpSessionAttributeListener {

   public ONGLFixListener()  {
   }

   public void contextInitialized(ServletContextEvent servletContextEvent)  {
       OgnlRuntime.setSecurityManager(null);
   }
  
   //Empty methods that do nothing for the interfaces

web.xml

  com.example.ONGLFixListener

This should fix the problem. =D