JBoss EAP 6.4: NoClassDefFoundError on class sun.security.jca.GetInstance

问题

I have a deployment that calls javax.crypto.SecretKeyFactory.getInstance.

The class javax.crypto.SecretKeyFactory appears to load correctly, but when the method tries to create an instance it throws a NoClassDefFoundError on sun/security/jca/GetInstance

Looking at the OpenJDK8 sources shows that relevant javax.crypto.SecretKeyFactory constructor refers explicitly to a method in sun.security.jca.GetInstance, so it's normal that it tries to load it.

What's odd is that both javax/crypto/SecretKeyFactory.class and sun/security/jca/GetInstance.class are present in /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.91-1.b14.el6.x86_64/jre/lib/rt.jar but that only the former is found by the classloader.

What is the jboss module classloader playing at and how can I get it to stop it?

Thanks for suggestions.

回答1:

Not all JDK classes are exposed to a deployment by default. If your deployment uses JDK classes that are not exposed you can get access to them using jboss-deployment-structure.xml with system dependencies:

<jboss-deployment-structure xmlns="urn:jboss:deployment-structure:1.1">
    <deployment>
        <dependencies>
            <system export="true">
                <paths>
                    <path name="sun/security/jca"/>
                </paths>
            </system>
        </dependencies>
    </deployment>
</jboss-deployment-structure>

Another alternative you can import the whole system module adding the following line to MANIFEST.MF:

Dependencies: system

Ref: Class Loading and Modules

回答2:

In your JBoss installation, go to directory modules/sun/jdk/main and edit the module.xml file there. In <dependencies>/<system>/<paths> add an element <path name="sun/security/jca"/>. Restart your JBoss instance and retry.

回答3:

I finally fixed my problem, though not quite in the ways suggested above. I wouldn't have got there without the help though (thanks guys).

I did manage to fix the sun/security/jca access problem but it then threw up another problem of a similar type, but with a javax class. I found an ugly fix for that by removing a jar from module org/jboss/genericjms and letting the jdk version get picked up, but I felt that that was playing around too much with stuff that I couldn't predict the consequences of.

The fix I have finally settled on is to put the provided jar that references javax/crypto/SecretKeyFactory in a new module all of its own and then to pull in the classes it needs via:

    <system export="true">
      <paths>
        <path name="java/sql"/>
        <path name="javax/crypto"/>
        <path name="javax/crypto/spec"/>
        <path name="javax/crypto/interfaces"/>
        <path name="javax/management"/>
        <path name="javax/security/auth/login"/>
        <path name="sun/security/jca"/>
        <path name="org/ietf/jgss"/>
      </paths>
    </system>

in the module.xml. When I reference this new module from my code it works (I pulled it in by making it a global module in standalone.xml in fact).

Problem solved. Though I have to say that after this experience of the jboss modular class loader, give me a hierarchical one any day.

Thanks again for the help.

来源：https://stackoverflow.com/questions/43327178/jboss-eap-6-4-noclassdeffounderror-on-class-sun-security-jca-getinstance

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