javascript - Cannot compile webapp sample of JasperReports

Question

It's my first time to run the the webapp sample of the JasperReports in the offical distribution. I put the jar in the dist and lib into the webapp sample and deployed the whole dir of the webapp-sample into tomcat. But when I try to use the default page to compile the WebappReport.jrxml, I see an error.jsp, and it shows me the following prompt:

JasperReports encountered this error :

net.sf.jasperreports.engine.JRException: Errors were encountered when compiling report expressions class file:
1. scriptlets.WebappScriptlet cannot be resolved to a type
                value = ((scriptlets.WebappScriptlet)((scriptlets.WebappScriptlet)parameter_REPORT_SCRIPTLET.getValue())).hello(); //$JR_EXPR_ID=23$
                          <------------------------>
2. scriptlets.WebappScriptlet cannot be resolved to a type
                value = ((scriptlets.WebappScriptlet)((scriptlets.WebappScriptlet)parameter_REPORT_SCRIPTLET.getValue())).hello(); //$JR_EXPR_ID=23$
                                                       <------------------------>
3. scriptlets.WebappScriptlet cannot be resolved to a type
                value = ((scriptlets.WebappScriptlet)((scriptlets.WebappScriptlet)parameter_REPORT_SCRIPTLET.getValue())).hello(); //$JR_EXPR_ID=23$
                          <------------------------>
4. scriptlets.WebappScriptlet cannot be resolved to a type
                value = ((scriptlets.WebappScriptlet)((scriptlets.WebappScriptlet)parameter_REPORT_SCRIPTLET.getValue())).hello(); //$JR_EXPR_ID=23$
                                                       <------------------------>
5. scriptlets.WebappScriptlet cannot be resolved to a type
                value = ((scriptlets.WebappScriptlet)((scriptlets.WebappScriptlet)parameter_REPORT_SCRIPTLET.getValue())).hello(); //$JR_EXPR_ID=23$
                          <------------------------>
6. scriptlets.WebappScriptlet cannot be resolved to a type
                value = ((scriptlets.WebappScriptlet)((scriptlets.WebappScriptlet)parameter_REPORT_SCRIPTLET.getValue())).hello(); //$JR_EXPR_ID=23$
                                                       <------------------------>
6 errors

at net.sf.jasperreports.engine.design.JRAbstractCompiler.compileReport(JRAbstractCompiler.java:191)
at net.sf.jasperreports.engine.JasperCompileManager.compileReport(JasperCompileManager.java:212)
at net.sf.jasperreports.engine.JasperCompileManager.compileReportToFile(JasperCompileManager.java:128)
at net.sf.jasperreports.engine.JasperCompileManager.compileReportToFile(JasperCompileManager.java:87)
at org.apache.jsp.jsp.compile_jsp._jspService(compile_jsp.java:61)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:388)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:291)
at org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:877)
at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:594)
at org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1675)
at java.lang.Thread.run(Thread.java:619)

Answer 1

This is due to a bug (in our case in JasperServer) where a report loaded from cache is being compiled by the JDT compiler is missing the scriptlet on the classpath. This does not happen when the report is run initially because in that case the JDT evaluator (instead of the compiler) is used with the scriptlet on the classpath. In other words:

1. Report is run using the JDT evaluator, scriptlet is added to the classpath
2. Report is loaded from cache and compiled using JDT compiler, without the scriptlet on the classpath (because the JDT compiler shares its classpath with the containing application, in contrary to the evaluator which has its own classpath).

The quick fix is to add the scriptlet to your containing application's classpath.