除了 jars 之外，避免在 Jetty 中扫描类路径 class

Question

To make Jetty 9.0 stop scanning classes and jars from classpath I did as described by it's docs: first I created a WEB-INF\jetty-web.xlm file on the project with the following:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE Configure PUBLIC "-//Jetty//Configure//EN" "http://www.eclipse.org/jetty/configure_9_3.dtd">

<Configure class="org.eclipse.jetty.webapp.WebAppContext">

    <Call name="setAttribute">
        <Arg>org.eclipse.jetty.server.webapp.WebInfIncludeJarPattern</Arg>
        <Arg>.\A</Arg>
    </Call>

</Configure>

Then on web.xml I specified both <absolute-ordering/> and metadata-complete="true and I run Jetty with -Dorg.eclipse.jetty.webapp.WebInfConfiguration.LEVEL=ALL and -Dorg.eclipse.jetty.annotations.AnnotationParser.LEVEL=DEBUG to confirm that the scanning was really being skipped, and that seems true for WebContext since there as was list of jars selected by the scanners and now only the project war is listed:

2021-02-07 21:43:58.971:INFO:oejsh.ContextHandler:Scanner-1: Started o.e.j.w.WebAppContext@6c7c5cac{Payroll,/payroll-groovy-1.0,file:///E:/Projetos/payroll_groovy/target/payroll-groovy-1.0/,AVAILABLE}{E:\Projetos\payroll_groovy\target\payroll-groovy-1.0.war}

However, AnnotationParser shows jar scanning (I don't understand the difference of both logs...):

2021-02-07 21:43:57.312:DBUG:oeja.AnnotationParser:qtp1595212853-27: Scanning class from jar file:///E:/Programas/jetty/lib/apache-jstl/org.apache.taglibs.taglibs-standard-impl-1.2.5.jar!/org/apache/taglibs/standard/Version.class->org/apache/taglibs/standard/Version.class[0]
2021-02-07 21:43:57.323:DBUG:oeja.AnnotationParser:qtp1595212853-29: Scanning class from jar file:///E:/Programas/jetty/lib/servlet-api-3.1.jar!/javax/servlet/AsyncEvent.class->javax/servlet/AsyncEvent.class[0]
2021-02-07 21:43:57.323:DBUG:oeja.AnnotationParser:qtp1595212853-29: Scanning class from jar file:///E:/Programas/jetty/lib/servlet-api-3.1.jar!/javax/servlet/AsyncListener.class->javax/servlet/AsyncListener.class[0]
2021-02-07 21:43:57.323:DBUG:oeja.AnnotationParser:qtp1595212853-27: Scanning class from jar file:///E:/Programas/jetty/lib/apache-jstl/org.apache.taglibs.taglibs-standard-impl-1.2.5.jar!/org/apache/taglibs/standard/functions/Functions.class->org/apache/taglibs/standard/functions/Functions.class[0]
2021-02-07 21:43:57.323:DBUG:oeja.AnnotationParser:qtp1595212853-29: Scanning class from jar file:///E:/Programas/jetty/lib/servlet-api-3.1.jar!/javax/servlet/DispatcherType.class->javax/servlet/DispatcherType.class[0]
2021-02-07 21:43:57.323:DBUG:oeja.AnnotationParser:qtp1595212853-29: Scanning class from jar file:///E:/Programas/jetty/lib/servlet-api-3.1.jar!/javax/servlet/Filter.class->javax/servlet/Filter.class[0]
2021-02-07 21:43:57.323:DBUG:oeja.AnnotationParser:qtp1595212853-27: Scanning class from jar file:///E:/Programas/jetty/lib/apache-jstl/org.apache.taglibs.taglibs-standard-impl-1.2.5.jar!/org/apache/taglibs/standard/resources/Resources.class->org/apache/taglibs/standard/resources/Resources.class[0]
2021-02-07 21:43:57.324:DBUG:oeja.AnnotationParser:qtp1595212853-29: Scanning class from jar file:///E:/Programas/jetty/lib/servlet-api-3.1.jar!/javax/servlet/FilterChain.class->javax/servlet/FilterChain.class[0]
2021-02-07 21:43:57.324:DBUG:oeja.AnnotationParser:qtp1595212853-27: Not a class: org/apache/taglibs/standard/resources/Resources.properties
2021-02-07 21:43:57.324:DBUG:oeja.AnnotationParser:qtp1595212853-27: Not a class: org/apache/taglibs/standard/resources/Resources_ja.properties
2021-02-07 21:43:57.324:DBUG:oeja.AnnotationParser:qtp1595212853-29: Scanning class from jar file:///E:/Programas/jetty/lib/servlet-api-3.1.jar!/javax/servlet/FilterConfig.class->javax/servlet/FilterConfig.class[0]
2021-02-07 21:43:57.324:DBUG:oeja.AnnotationParser:qtp1595212853-27: Scanning class from jar file:///E:/Programas/jetty/lib/apache-jstl/org.apache.taglibs.taglibs-standard-impl-1.2.5.jar!/org/apache/taglibs/standard/tag/common/core/CatchTag.class->org/apache/taglibs/standard/tag/common/core/CatchTag.class[0]
2021-02-07 21:43:57.324:DBUG:oeja.AnnotationParser:qtp1595212853-29: Scanning class from jar file:///E:/Programas/jetty/lib/servlet-api-3.1.jar!/javax/servlet/FilterRegistration$Dynamic.class->javax/servlet/FilterRegistration$Dynamic.class[0]

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.
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and it keeps on until every jar and every class from the project are listed. If I add this in the jetty-web.xml:

<Call name="setAttribute">
    <Arg>org.eclipse.jetty.server.webapp.ContainerIncludeJarPattern</Arg>
    <Arg>.\A</Arg>
</Call>

then the log shows that the jar scanning ceased, but that is not the case for classes from the classpath:

2021-02-07 21:50:13.730:DBUG:oeja.AnnotationParser:qtp1595212853-29: Scanning class file:///E:/Projetos/payroll_groovy/target/payroll-groovy-1.0/WEB-INF/classes/com/vmc/DynamicClassFactory$_coreLangMethods_closure1.class
2021-02-07 21:50:13.737:DBUG:oeja.AnnotationParser:qtp1595212853-29: Scanning class file:///E:/Projetos/payroll_groovy/target/payroll-groovy-1.0/WEB-INF/classes/com/vmc/DynamicClassFactory$__clinit__closure2.class
2021-02-07 21:50:13.738:DBUG:oeja.AnnotationParser:qtp1595212853-29: Scanning class file:///E:/Projetos/payroll_groovy/target/payroll-groovy-1.0/WEB-INF/classes/com/vmc/DynamicClassFactory$__clinit__closure3.class
2021-02-07 21:50:13.739:DBUG:oeja.AnnotationParser:qtp1595212853-29: Scanning class file:///E:/Projetos/payroll_groovy/target/payroll-groovy-1.0/WEB-INF/classes/com/vmc/DynamicClassFactory.class
2021-02-07 21:50:13.741:DBUG:oeja.AnnotationParser:qtp1595212853-29: Scanning class file:///E:/Projetos/payroll_groovy/target/payroll-groovy-1.0/WEB-INF/classes/com/vmc/objectMemento/Caretaker.class
2021-02-07 21:50:13.742:DBUG:oeja.AnnotationParser:qtp1595212853-29: Scanning class file:///E:/Projetos/payroll_groovy/target/payroll-groovy-1.0/WEB-INF/classes/com/vmc/objectMemento/InMemoryObjectChangeProvider.class
2021-02-07 21:50:13.743:DBUG:oeja.AnnotationParser:qtp1595212853-29: Scanning class file:///E:/Projetos/payroll_groovy/target/payroll-groovy-1.0/WEB-INF/classes/com/vmc/objectMemento/Memento.class

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.
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The odd thing is that @WebListener annotated classes from my classpath were not loaded (maybe because of metadata-complete setting?) despite AnnotationParser telling that they were all scanned. In any case, I would like to avoid all scanning since there will be no @WebListener annotated classes (I put it just for testing) and so there is no sense on spent time scanning them.

So how do I stop Jetty 9.0 from scanning classes from my classpath?

Answer 1

Jetty 9.0? Make sure you are using Jetty 9.4.x at least. The Jetty 9.0 major version is using a pre-release/alpha version of the Servlet 3.1 specs. You want to go from 9.0 to 9.4 (that's a jump of 4 major versions of Jetty within the Servlet 3.1 top level, so be prepared.)

Reminder, Jetty versioning (as it has been since 1995) is
<servlet_support>.<major_version>.<minor_version>

• Jetty 9.x means Servlet 3.1,
• Jetty 10.x means Servlet 4.0
• Jetty 11.x means Servlet 5.0

The next value is the major version within that servlet support level.

As for your attempts to use the org.eclipse.jetty.server.webapp.WebInfIncludeJarPattern attribute to limit what is scanned in the WEB-INF/lib , this is the correct attribute to use, but can only exist in the XML deployable files.

This is the ${jetty.base}/webapps/<name>.xml location.

Your attempted use of WEB-INF/jetty-web.xml is incorrect, as this file is applied after all of the servlet specific behaviors are fully configured. (and servlet specific behaviors is what you want to configure)

You need to configure this attribute at the very beginning of the deployment process, which means the only place to define it is within the XML deployable.

Based on your logging output of Payroll,/payroll-groovy-1.0,file:///E:/Projetos/payroll_groovy/target/payroll-groovy-1.0/,AVAILABLE}{E:\Projetos\payroll_groovy\target\payroll-groovy-1.0.war the XML would be...

<?xml version="1.0"?>
<!DOCTYPE Configure PUBLIC "-//Jetty//Configure//EN" "http://www.eclipse.org/jetty/configure_9_3.dtd">

<Configure class="org.eclipse.jetty.webapp.WebAppContext">
  <Set name="contextPath">/Payroll</Set>
  <Set name="war">E:/Projetos/payroll_groovy/target/payroll-groovy-1.0.war</Set>
  <Call name="setAttribute">
    <Arg>org.eclipse.jetty.server.webapp.WebInfIncludeJarPattern</Arg>
    <Arg>.*/scannable-[^/]*\.jar$</Arg>
  </Call>
</Configure>

That will deploy your war, and only scan jar files in WEB-INF/lib that start with scannable- .