Basically, a special subclass of a CustomExpression (HyperLinkExpression in fact) is binded to a column where the developer return a String with the desired URL.
Fragment from HyperLinkReportTest, there you can see how column 3 and 4 have a hyperlinks
drb.getColumn(3).setHyperLinkExpression(new HyperLinkExpression() {
public Object evaluate(Map fields, Map variables, Map parameters) {
return "http://linkInImage.com?param=" + variables.get("REPORT_COUNT");
}
});
drb.getColumn(4).setHyperLinkExpression(new HyperLinkExpression() {
public Object evaluate(Map fields, Map variables, Map parameters) {
return "http://thisIsAURL?count=" + variables.get("REPORT_COUNT");
}
});