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https://issues.apache.org/jira/browse/SLING-6458?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15821647#comment-15821647
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Felix Meschberger commented on SLING-6458:
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There are two topics here:
* First that we are based on an old and venerable Jasper version. Unfortunately
we have made some changes to Jasper, that are not integrated upstream (as they
are Sling specific) so upgrading is not trivial. Nevertheless at one point in
time we should upgrade to a more recent Jasper version, which my gut tells me
should rather be from the Tomcat 8 or even Tomcat 9 series.
* Second the compiler converting the Java Code generated by Jasper to Byte
Code. We are embedding the Eclipse compiler and it looks like that version of
the Compiler does not support Java 8 (yet).
So, my impression for this issue is, that we basically should be upgrading the
embedded Eclipse Compiler to the most recent version supporting Java 8 (and
make sure the source/target version numbers for configuration support Java 8 as
well)
> JSP scripting does not support Java 8 features (lambdas, method references,
> etc)
> --------------------------------------------------------------------------------
>
> Key: SLING-6458
> URL: https://issues.apache.org/jira/browse/SLING-6458
> Project: Sling
> Issue Type: Bug
> Components: Scripting
> Affects Versions: Scripting JSP 2.0.28, Scripting JSP 2.1.0, Scripting JSP
> 2.1.4, Scripting JSP 2.1.6, Scripting JSP 2.1.8, Scripting JSP 2.2.0,
> Scripting JSP 2.2.2, Scripting JSP 2.2.4, Scripting JSP 2.2.6
> Reporter: Henry Kuijpers
>
> When trying to use Java 8 functionality in a JSP file, the Jasper framework
> in the Sling Scripting bundle fails to compile the JSP file. It seems to get
> stuck on a Java 8 feature: Lambdas.
> {code}
> <%@page session="false" %>
> <%@ page import="java.util.stream.IntStream" %>
> <%@ page import="java.io.IOException" %>
> <%
> out.println("Lambda test");
> IntStream leip = IntStream.of(1, 2, 3, 4, 5, 6);
> final JspWriter out2 = out;
> leip.forEach(x -> {
> try {
> out2.println(x);
> } catch (IOException e) {
> // Intentionally do nothing
> }
> });
> %>
> {code}
> When we remove the complete "leip.forEach" statement, the code compiles and
> executes successfully.
> Upon further investigation, I found out that the Jasper compiler that is
> being used, does not have support for "tag 18", which seems to be the lambda
> feature in Java 8.
> I could find the constant pool tags over here:
> https://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.html#jvms-4.4-140
> Clearly, there is no support for MethodHandle, MethodType, InvokeDynamic.
> I could find a bug report for Tomcat (where Jasper is developed) over here:
> https://bz.apache.org/bugzilla/show_bug.cgi?id=54475
> It seems that the issue was fixed in a newer version of Jasper, namely
> 6.0.40. We are currently using 6.0.14 (which is in Apache Sling Scripting JSP
> version bundle version 2.1.4).
> I tried looking at
> https://mvnrepository.com/artifact/org.apache.sling/org.apache.sling.scripting.jsp
> but for some reason all newer versions are also embedding Jasper 6.0.14
> (which does not support Java 8) and in the custom code inside that bundle I
> also do not see any cases for 18 in the switch statement in
> SmapUtil$SDEInstaller.copyConstantPool. Nor do I see any traces that look
> like this fix:
> https://bz.apache.org/bugzilla/attachment.cgi?id=31416&action=diff
> See below a stacktrace of what's happening:
> {code}
> 12.01.2017 14:39:19.063 *ERROR* [144.119.190.210 [1484228359038] POST
> /content/page/sign-up.html HTTP/1.1]
> org.apache.sling.servlets.get.impl.DefaultGetServlet No renderer for
> extension html, cannot render resource ResourceWrapper,
> type=test/components/form/actions/register,
> path=/content/page/sign-up/jcr:content/par/start, resource=[JcrNodeResource,
> type=foundation/components/form/start, superType=null,
> path=/content/page/sign-up/jcr:content/par/start]
> 12.01.2017 14:39:19.079 *ERROR* [144.119.190.210 [1484228359038] POST
> /content/page/sign-up.html HTTP/1.1] com.day.cq.wcm.tags.IncludeTag Error
> while executing script
> /apps/test/components/form/actions/register/post.POST.jsp
> org.apache.sling.api.scripting.ScriptEvaluationException:
> org.apache.sling.scripting.jsp.jasper.JasperException: Unable to compile
> class for JSP
> at
> org.apache.sling.scripting.core.impl.DefaultSlingScript.call(DefaultSlingScript.java:388)
> at
> org.apache.sling.scripting.core.impl.DefaultSlingScript.eval(DefaultSlingScript.java:171)
> at
> org.apache.sling.scripting.core.impl.DefaultSlingScript.service(DefaultSlingScript.java:463)
> at com.day.cq.wcm.tags.IncludeTag.includeScript(IncludeTag.java:167)
> at com.day.cq.wcm.tags.IncludeTag.doEndTag(IncludeTag.java:87)
> at
> org.apache.sling.scripting.jsp.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
> at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
> at
> org.apache.sling.scripting.jsp.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:502)
> at
> org.apache.sling.scripting.jsp.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:449)
> at
> org.apache.sling.scripting.jsp.JspScriptEngineFactory.callJsp(JspScriptEngineFactory.java:281)
> at
> org.apache.sling.scripting.jsp.JspScriptEngineFactory.access$100(JspScriptEngineFactory.java:102)
> at
> org.apache.sling.scripting.jsp.JspScriptEngineFactory$JspScriptEngine.eval(JspScriptEngineFactory.java:524)
> at
> org.apache.sling.scripting.core.impl.DefaultSlingScript.call(DefaultSlingScript.java:361)
> at
> org.apache.sling.scripting.core.impl.DefaultSlingScript.eval(DefaultSlingScript.java:171)
> at
> org.apache.sling.scripting.core.impl.DefaultSlingScript.service(DefaultSlingScript.java:463)
> at
> org.apache.sling.engine.impl.request.RequestData.service(RequestData.java:508)
> at
> org.apache.sling.engine.impl.filter.SlingComponentFilterChain.render(SlingComponentFilterChain.java:45)
> ... filters ommitted for brevity ...
> at
> com.day.j2ee.servletengine.RequestDispatcherImpl.doFilter(RequestDispatcherImpl.java:321)
> at
> com.day.j2ee.servletengine.RequestDispatcherImpl.service(RequestDispatcherImpl.java:340)
> at
> com.day.j2ee.servletengine.RequestDispatcherImpl.service(RequestDispatcherImpl.java:383)
> at
> com.day.j2ee.servletengine.ServletHandlerImpl.process(ServletHandlerImpl.java:335)
> at
> com.day.j2ee.servletengine.HttpListener$Worker.run(HttpListener.java:644)
> at java.lang.Thread.run(Thread.java:745)
> Caused by: org.apache.sling.api.SlingException:
> org.apache.sling.scripting.jsp.jasper.JasperException: Unable to compile
> class for JSP
> at
> org.apache.sling.scripting.jsp.jasper.servlet.JspServletWrapper.handleJspExceptionInternal(JspServletWrapper.java:691)
> at
> org.apache.sling.scripting.jsp.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:608)
> at
> org.apache.sling.scripting.jsp.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:525)
> at
> org.apache.sling.scripting.jsp.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:449)
> at
> org.apache.sling.scripting.jsp.JspScriptEngineFactory.callJsp(JspScriptEngineFactory.java:281)
> at
> org.apache.sling.scripting.jsp.JspScriptEngineFactory.access$100(JspScriptEngineFactory.java:102)
> at
> org.apache.sling.scripting.jsp.JspScriptEngineFactory$JspScriptEngine.eval(JspScriptEngineFactory.java:524)
> at
> org.apache.sling.scripting.core.impl.DefaultSlingScript.call(DefaultSlingScript.java:361)
> ... 121 more
> Caused by: java.io.IOException: unexpected tag: 18
> at
> org.apache.sling.scripting.jsp.jasper.compiler.SmapUtil$SDEInstaller.copyConstantPool(SmapUtil.java:491)
> at
> org.apache.sling.scripting.jsp.jasper.compiler.SmapUtil$SDEInstaller.addSDE(SmapUtil.java:308)
> at
> org.apache.sling.scripting.jsp.jasper.compiler.SmapUtil$SDEInstaller.<init>(SmapUtil.java:264)
> at
> org.apache.sling.scripting.jsp.jasper.compiler.SmapUtil$SDEInstaller.install(SmapUtil.java:243)
> at
> org.apache.sling.scripting.jsp.jasper.compiler.SmapUtil.installSmap(SmapUtil.java:167)
> at
> org.apache.sling.scripting.jsp.jasper.compiler.JDTCompiler.generateClass(JDTCompiler.java:151)
> at
> org.apache.sling.scripting.jsp.jasper.compiler.Compiler.compile(Compiler.java:312)
> at
> org.apache.sling.scripting.jsp.jasper.compiler.Compiler.compile(Compiler.java:290)
> at
> org.apache.sling.scripting.jsp.jasper.compiler.Compiler.compile(Compiler.java:277)
> at
> org.apache.sling.scripting.jsp.jasper.JspCompilationContext.compile(JspCompilationContext.java:501)
> at
> org.apache.sling.scripting.jsp.jasper.servlet.JspServletWrapper.prepareServlet(JspServletWrapper.java:427)
> at
> org.apache.sling.scripting.jsp.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:486)
> ... 126 more
> {code}
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