Finding resources in JasperReports
From iDempiere en
Images
Resources such as images that are attachments can be referenced using $P{RESOURCE_DIR}.
An image path would look like
$P{RESOURCE_DIR} + "image.jpg"
Resource bundles
Resource bundles are property files for translating reports into different languages.
By default iDempiere-JasperReports looks for a resource file with the same name as the JasperFile, ie, the Jasperfile is called Report.jasper and then it will look for Report.properties and Report_en_US.properties etc. This might be practical if you only have one single report and have no need to share translations between different reports.
