Trying to do the simple HelloWorld java application for portal

Question

Hi:
i've been trying to do the simple java application HelloWorld so that i can get a view of how will it be to integrate a pure java application that we have in a later step. The fact is that i've been following "how to build a java portlet" and "packaging and deploying your provider" documents.
i've taken the code from that document:
public class HelloWorldApp {
public static void main (string[] args){
//Display "Hello World!"
System.out.println("Hello World!");
That's my java code. (in fact i want to do this as a trial, 'cause later i will
do the same with a java application of our own).
So i compiled it, taken the .class, jar it and packaged it as told in the
second document.
I've deployed it in OC4J_portal and when i try to access the URL i get an
error:
500 Internal Server Error
java.lang.NoSuchMethodException
     at java.lang.Class.getMethod0(Native Method)
     at java.lang.Class.getMethod(Class.java:888)
     at oracle.portal.provider.v2.render.http.JavaRenderer.postInitialize(Unknown Source)
     at oracle.portal.utils.xml.v2.DefaultNodeHandler.invokePostInitialize(Unknown Source)
     at oracle.portal.utils.xml.v2.DefaultNodeHandler.processNode(Unknown Source)
     at oracle.portal.utils.xml.v2.DefaultNodeHandler.processNode(Unknown Source)
     at oracle.portal.utils.xml.v2.DefaultNodeHandler.processNode(Unknown Source)
     at oracle.portal.provider.v2.http.DefaultProviderLoader.getProviderDefinition(Unknown Source)
     at oracle.portal.provider.v2.http.DefaultProviderLoader.init(Unknown Source)
     at oracle.webdb.provider.v2.adapter.soapV1.ProviderAdapter.init(Unknown Source)
     at oracle.webdb.provider.v2.utils.soap.SOAPProcessor.locateService(Unknown Source)
     at oracle.webdb.provider.v2.adapter.SOAPServlet.doHTTPCall(Unknown Source)
     at oracle.webdb.provider.v2.adapter.SOAPServlet.service(Unknown Source)
     at javax.servlet.http.HttpServlet.service(HttpServlet.java:336)
     at com.evermind[Oracle9iAS (9.0.2.0.0) Containers for J2EE].server.http.ResourceFilterChain.doFilter(ResourceFilterChain.java:59)
     at oracle.security.jazn.oc4j.JAZNFilter.doFilter(JAZNFilter.java:283)
     at com.evermind[Oracle9iAS (9.0.2.0.0) Containers for J2EE].server.http.ServletRequestDispatcher.invoke(ServletRequestDispatcher.java:523)
     at com.evermind[Oracle9iAS (9.0.2.0.0) Containers for J2EE].server.http.ServletRequestDispatcher.forwardInternal(ServletRequestDispatcher.java:269)
     at com.evermind[Oracle9iAS (9.0.2.0.0) Containers for J2EE].server.http.HttpRequestHandler.processRequest(HttpRequestHandler.java:735)
     at com.evermind[Oracle9iAS (9.0.2.0.0) Containers for J2EE].server.http.AJPRequestHandler.run(AJPRequestHandler.java:151)
     at com.evermind[Oracle9iAS (9.0.2.0.0) Containers for J2EE].util.ThreadPoolThread.run(ThreadPoolThread.java:64)
does anybody know how to solve this problem?
Thx.
Regards. Urko.

Answer 1

Hi Urko,
Such an application as you have quoted will not have much luck as a Portlet - the code you supplied simply writes "Hello World" to standard out!
Think of a portlet more like a servlet - you have an output stream to write to which, under the covers, is wired back up to the Portal Server which assembles the content into the page seen in the browser.
Take a look at the extensive range of sample Java Portlets available with the PDK download.
Anyway, from the stack trace it looks like you're using JavaRenderer. JavaRenderer invokes an arbitrarily named method on an arbitrary class **provided** that method takes a single argument of type PortletRenderRequest. So you would need something like:-
public class MyApp
// A bunch of app-specific code.
public void renderPortlet(PortletRenderRequest pr)
PrintWriter out = pr.getWriter();
out.println("<b>Hello World</b>");
Then, the relevant provider.xml section would look something like this....
<showPage class="oracle.portal.provider.v2.render.http.JavaRenderer>
<className>MyApp</className>
<renderMethod>renderPortlet</renderMethod>
</showPage>
Hope this helps.....
Regards,
Gareth
PDK-Java Development Team