0

We're trying to move a website built mostly from JSPs from Websphere to Jetty. We're having a problem with NullPointerException evaluating EL code in test attributes:

<c:if test="${requestScope.domainSpecificName}">

The problem is that the domainSpecificName attribute is either set to true or not present in the request.

In Websphere this line is compiled to

_jspx_th_c_if_0.setTest(((java.lang.Boolean) org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate("${requestScope.domainSpecificName}", boolean.class, (PageContext)pageContext, _jspx_fnmap, false)).booleanValue());

(Note the class is boolean and the default value is false.)

The same line of the JSP, in Jetty, compiles to

_jspx_th_c_if_0.setTest(((java.lang.Boolean) org.apache.jasper.runtime.PageContextImpl.evaluateExpression("${requestScope.domainSpecificName}", java.lang.Boolean.class, (PageContext)_jspx_page_context, null)).booleanValue());

Here we have a class of Boolean and a default value of null, which obviously will throw a NPE if the attribute is not present.

From the documentation, it sounds like if we can set JexlBuilder.strict(false) it will not treat null values as errors. (Although I'm not sure how that would be compiled.)

Does anyone know how to configure JexlBuilder inside Jetty?

Alternatively, if I'm heading down the wrong path; does anyone know the correct way to be handling this? There are hundreds of instances of <c:if test="${...}"> that might throw NPEs, so at least in the short term fixing them all is not practical.

DavidW
  • 1,413
  • 10
  • 17

1 Answers1

0

JSP Support in Jetty uses Apache Jasper, which uses Apache EL, which uses javax.el.

javax.el has no JexlBuilder style class.

Perhaps one of the Apache JSP or Apache EL system properties will help you.

See: https://tomcat.apache.org/tomcat-8.0-doc/config/systemprops.html

Joakim Erdfelt
  • 46,896
  • 7
  • 86
  • 136
  • For whatever reason, it appears that our deployed instance is using the glassfish implementation of `javax.el` which doesn't seem to have those properties. Thanks for your suggestion, though. – DavidW Sep 17 '19 at 18:16
  • Then you have a very old and long out of date [version of Jetty](https://www.eclipse.org/jetty/documentation/current/what-jetty-version.html). The Jetty project moved away from the Glassfish JSP implementation due to too many bugs about 7 years ago. – Joakim Erdfelt Sep 17 '19 at 18:42