tomcat - 无法在 Java9 项目中处理文件 module-info.class 导致 ClassFormatException

Question

尝试Run Vaadin 8.1 app under Java 9 prerelease in IntelliJ 2017.2.2我能够使用 fresh project 构建 vaadinjavanine.war并使用 Jetty Server 托管相同的内容。

我最终尝试将生成的 war 部署到 tomcat 服务器。但是，在 tomcat 服务器启动过程中，出现以下异常:

21-Aug-2017 22:53:38.830 SEVERE [localhost-startStop-1] org.apache.catalina.startup.ContextConfig.processAnnotationsFile Unable to process file [/Library/Tomcat/apache-tomcat-8.0.22/webapps/vaadinjavanine/WEB-INF/classes/module-info.class] for annotations
 org.apache.tomcat.util.bcel.classfile.ClassFormatException: Invalid byte tag in constant pool: 19
    at org.apache.tomcat.util.bcel.classfile.Constant.readConstant(Constant.java:97)
    at org.apache.tomcat.util.bcel.classfile.ConstantPool.<init>(ConstantPool.java:55)
    at org.apache.tomcat.util.bcel.classfile.ClassParser.readConstantPool(ClassParser.java:177)
    at org.apache.tomcat.util.bcel.classfile.ClassParser.parse(ClassParser.java:85)
    at org.apache.catalina.startup.ContextConfig.processAnnotationsStream(ContextConfig.java:2011)
    at org.apache.catalina.startup.ContextConfig.processAnnotationsFile(ContextConfig.java:1994)
    at org.apache.catalina.startup.ContextConfig.processAnnotationsFile(ContextConfig.java:1988)
    at org.apache.catalina.startup.ContextConfig.processAnnotationsUrl(ContextConfig.java:1939)
    at org.apache.catalina.startup.ContextConfig.processAnnotations(ContextConfig.java:1897)
    at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1149)
    at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:771)
    at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:305)
    at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:117)
    at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:90)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5066)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:725)
    at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:701)
    at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:717)
    at org.apache.catalina.startup.HostConfig.deployWAR(HostConfig.java:945)
    at org.apache.catalina.startup.HostConfig$DeployWar.run(HostConfig.java:1768)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)

21-Aug-2017 22:53:38.980 SEVERE [localhost-startStop-1] org.apache.catalina.core.ContainerBase.addChildInternal ContainerBase.addChild: start: 
 org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/vaadinjavanine]]
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154)
    at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:725)
    at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:701)
    at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:717)
    at org.apache.catalina.startup.HostConfig.deployWAR(HostConfig.java:945)
    at org.apache.catalina.startup.HostConfig$DeployWar.run(HostConfig.java:1768)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.UnsupportedClassVersionError: nullpointer/MyUI$MyUIServlet has been compiled by a more recent version of the Java Runtime (class file version 53.0), this version of the Java Runtime only recognizes class file versions up to 52.0 (unable to load class nullpointer.MyUI$MyUIServlet)
    at org.apache.catalina.loader.WebappClassLoaderBase.findClassInternal(WebappClassLoaderBase.java:2476)
    at org.apache.catalina.loader.WebappClassLoaderBase.findClass(WebappClassLoaderBase.java:854)
    at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1274)
    at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1157)
    at org.atmosphere.util.IOUtils.isAtmosphere(IOUtils.java:381)
    at org.atmosphere.cpr.ContainerInitializer.onStartup(ContainerInitializer.java:58)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5156)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    ... 10 more

21-Aug-2017 22:53:38.981 SEVERE [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployWAR Error deploying web application archive /Library/Tomcat/apache-tomcat-8.0.22/webapps/vaadinjavanine.war
 java.lang.IllegalStateException: ContainerBase.addChild: start: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/vaadinjavanine]]
    at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:728)
    at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:701)
    at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:717)
    at org.apache.catalina.startup.HostConfig.deployWAR(HostConfig.java:945)
    at org.apache.catalina.startup.HostConfig$DeployWar.run(HostConfig.java:1768)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)

该异常表明无法处理从 Java9 的 module-info.java 生成的 module-info.class。 有办法解决这个问题吗？或者这实际上意味着 tomcat 还没有准备好使用 java9 模块？

注意:作为 Tomcat 的新手，我没有自定义任何设置。如果可以分享其他内容以获取更多信息，请告诉我。

Answer 1

我不是 Tomcat 专家，但看起来模块描述符并不是最严重的问题。下一个异常包含此 block :

Caused by: java.lang.UnsupportedClassVersionError: nullpointer/MyUI$MyUIServlet has been compiled by a more recent version of the Java Runtime (class file version 53.0), this version of the Java Runtime only recognizes class file versions up to 52.0 (unable to load class nullpointer.MyUI$MyUIServlet)

这使得您看起来像是在 Java 8(类文件版本 52)上运行 Tomcat，而您的代码是使用 Java 9(类文件版本 53)编译的。

确保在 Java 9 上运行 Tomcat。此外，您可能想尝试 early access build of Tomcat 9 ，这是 Java 9 兼容性所必需的。