Talking to Java Code from Ruby


#1

I’m attempting to use YAJB to talk to JasperReports from Ruby.

Please scream at me right now if there’s a better way to get to
JasperReports.

This is what I have so far:

-------------------BEGIN------------------
require ‘yajb/jbridge’
require ‘fileutils’
include JavaBridge

$REPORTS_LIB_DIR = “/home/kevin/dli/” + “backend/reports_module/lib/”

path = “$CLASSPATH”
FileUtils::cd($REPORTS_LIB_DIR) do
Dir["*.jar"].each { |name|
path += “:#{$REPORTS_LIB_DIR + name}/”
}
end

JBRIDGE_OPTIONS = {
:classpath => path
}

jimport “net.sf.jasperreports.engine.*”
jimport “java.util.HashMap”

jasperReport = jnew :JasperCompileManager
jasperReport.compileReport(
“/home/kevin/dli/backend/reports_module/report_templates/VirtualizerReport.jrxml”);

hash = jnew :HashMap
data = jnew :JREmptyDataSource

jasperPrint = jnew :JasperFillManager
jasperPrint.fillReport(jasperReport, hash, data)
-------------------END------------------

This does just fine for compiling the report, but when I try to call
fillReport, the world blows up:
/usr/local/lib/site_ruby/1.8/yajb/bstream.rb:655:in value': java.lang.RuntimeException (JavaBridge::JException) No such method: fillReport in net.sf.jasperreports.engine.JasperFillManager java.lang.RuntimeException: No such method: fillReport in net.sf.jasperreports.engine.JasperFillManager at jbridge.BridgeServer.generalCall(BridgeServer.java:145) at jbridge.BridgeServer.call(BridgeServer.java:179) at jbridge.comm.binstream.BStream_JBServer$2.send(BStream_JBServer.java:140) at jbridge.comm.binstream.MessageServer$MethodInvocation.run(MessageServer.java:456) at jbridge.InvocationPool$Worker.workloop(InvocationPool.java:97) at jbridge.InvocationPool$Worker.access$000(InvocationPool.java:55) at jbridge.InvocationPool$1.run(InvocationPool.java:62) at java.lang.Thread.run(Unknown Source) from /usr/local/lib/site_ruby/1.8/yajb/bstream.rb:810:insend_message’
from /usr/local/lib/site_ruby/1.8/yajb/bstream.rb:1048:in
send_message' from /usr/local/lib/site_ruby/1.8/yajb/comm_bstream.rb:59:insend_message_to_java’
from /usr/local/lib/site_ruby/1.8/yajb/jbridge.rb:506:in
__send_message_to_java' from /usr/local/lib/site_ruby/1.8/yajb/jbridge.rb:739:incall
from /usr/local/lib/site_ruby/1.8/yajb/jbridge.rb:685:in
`method_missing’
from ./testing_stub.rb:35

I could see why it would get confused. It’s an overloaded method. I’ve
poured over the docs for yajb but haven’t found anywhere that explains
how to
force calls of overloaded methods. I would like to use yajb because
it’s
pure ruby and pure java, meaning no compiling, and installs are easy.
The
communication being slow makes almost zero difference to me because I
won’t
be doing very much communication, just spawning off processor hogs with
the
thing.

So is there a way to specify types for overloaded methods, or do I need
to use
RJB (http://arton.no-ip.info/collabo/backyard/?RubyJavaBridge)? Or do I
need
to be slapped across the face with a wet trout for not seeing the easy
solution?


#2

On Sunday 25 December 2005 13:42, Kevin B. wrote:

I’m attempting to use YAJB to talk to JasperReports from Ruby.

Please scream at me right now if there’s a better way to get to
JasperReports.

For anyone who cares, I’m using RJB and it’s working fine now. So that
was my
solution. :slight_smile:


#3

Hi,

Sorry for late response.

I think JasperFillManager does not have the method
fillReport(JasperCompileManager,Map,JRDataSource).

How about following code?
-------------------BEGIN------------------
(snip)
:
manager = jnew :JasperCompileManager
jasperReport = manager.compileReport(path_to_template)
:
-------------------END------------------

I could see why it would get confused. It’s an overloaded method. I’ve
poured over the docs for yajb but haven’t found anywhere that explains how to
force calls of overloaded methods.

The yajb tries to search the overloaded method as java does.
So, giving appropriate arguments, you can choose the method.

Because the difference of typing between ruby (duck-typing) and java
(strong typing) is great, I’m not sure that the method searching code
is complete. If you are interesting in the code, please see the url
(served by gonzui at RAA)

http://raa.ruby-lang.org/gonzui/markup/yajb/src/java_src/jbridge/MethodFinder.java