java - How to set the image expression to always store the right image path

Question

I'm using JasperReports to create a report dynamically through Java. I have problem with the image expression (image path). This is the way I pass it now :

JRDefaultStyleProvider JRDefaultStyleProvider = null;
JRDesignImage image = new JRDesignImage(JRDefaultStyleProvider);
image.setX(0);
image.setY(0);
image.setWidth(200);
image.setHeight(200);
exp = new JRDesignExpression();
**exp.setText(""D:/MyProgram/src/myprogram/images/logo.png"");**
image.setExpression(exp);
image.setStyle(styles.imageStyle);
title_band.addElement(image);

It works fine, but if I change the location of MyProgram I'll have to also change the path in the expression. I tried setting the expression to : ../images/logo.png but I got an error of "Byte data not found at : ../images/logo.png". Any help would be appreciated.

Answer 1

There are several things that you could do.

One is to manually add a parameter called ProjectRoot in the report, use $P{ProjectRoot} + "images/logo.png" as image expression, and pass a value for ProjectRoot (taken from the environment) when you run the report.

Another approach is to leverage the fact that JasperReports also attempts to resolve image locations as classloader resources. Therefore if you add src/myprogram as a source folder so that images/logo.png gets to be part of your project's classpath at runtime, you'll be able to use "images/logo.png" as image expression.

A third solution is to register a FileRepositoryService extension in a JasperReportsContext instance that you would use for filling the report. The file repository service would be created with the current project root path, that you need to somehow determine from the environment. Having a repository service would also allow you to use "images/logo.png" as image expression. The code would look something like this:

SimpleJasperReportsContext context = new SimpleJasperReportsContext();
FileRepositoryService fileRepository = new FileRepositoryService(context, "D:/MyProgram/src/myprogram/", false);
context.setExtensions(RepositoryService.class, Collections.singletonList(fileRepository));
context.setExtensions(PersistenceServiceFactory.class, Collections.singletonList(FileRepositoryPersistenceServiceFactory.getInstance()));

JasperPrint jasperPrint = JasperFillManager.getInstance(context).fill(jasperReport, params);