Java 9 踩坑之启动参数

Java 9 出来一段时间了，也试着在Java 9 下运行jAlbum，原以为以Java一贯的向下兼容原则，应该都不用重新在JDK9编译，直接运行即可。然鹅，运行时报错，找不到类文件：

完整的失败日志为：

[2018-01-24 22:48:42.104 ERROR] [main  web.context.ContextLoader:220] - Context initialization failed
org.springframework.beans.factory.BeanDefinitionStoreException: Unexpected exception parsing XML document from ServletContext resource [/WEB-INF/beans.xml]; nested exception is org.springframework.beans.FatalBeanException: Invalid NamespaceHandler class [org.apache.cxf.jaxrs.spring.NamespaceHandler] for namespace [http://cxf.apache.org/jaxrs]: problem with handler class file or dependent class; nested exception is java.lang.NoClassDefFoundError: javax/xml/bind/JAXBException
	at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:412)
	at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:334)
	at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:302)
	at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:143)
	at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:178)
	at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:149)
	at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:124)
	at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:93)
	at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:130)
	at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:467)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:397)
	at org.springframework.web.context.ContextLoader.createWebApplicationContext(ContextLoader.java:276)
	at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:197)
	at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:47)
	at org.eclipse.jetty.server.handler.ContextHandler.callContextInitialized(ContextHandler.java:890)
	at org.eclipse.jetty.servlet.ServletContextHandler.callContextInitialized(ServletContextHandler.java:532)
	at org.eclipse.jetty.server.handler.ContextHandler.startContext(ContextHandler.java:853)
	at org.eclipse.jetty.servlet.ServletContextHandler.startContext(ServletContextHandler.java:344)
	at org.eclipse.jetty.webapp.WebAppContext.startWebapp(WebAppContext.java:1501)
	at org.eclipse.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1463)
	at org.eclipse.jetty.server.handler.ContextHandler.doStart(ContextHandler.java:785)
	at org.eclipse.jetty.servlet.ServletContextHandler.doStart(ServletContextHandler.java:261)
	at org.eclipse.jetty.webapp.WebAppContext.doStart(WebAppContext.java:545)
	at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)
	at org.eclipse.jetty.util.component.ContainerLifeCycle.start(ContainerLifeCycle.java:131)
	at org.eclipse.jetty.server.Server.start(Server.java:452)
	at org.eclipse.jetty.util.component.ContainerLifeCycle.doStart(ContainerLifeCycle.java:105)
	at org.eclipse.jetty.server.handler.AbstractHandler.doStart(AbstractHandler.java:113)
	at org.eclipse.jetty.server.Server.doStart(Server.java:419)
	at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)
	at com.shentar.frontend.FrontMain.main(FrontMain.java:106)
Caused by: org.springframework.beans.FatalBeanException: Invalid NamespaceHandler class [org.apache.cxf.jaxrs.spring.NamespaceHandler] for namespace [http://cxf.apache.org/jaxrs]: problem with handler class file or dependent class; nested exception is java.lang.NoClassDefFoundError: javax/xml/bind/JAXBException
	at org.springframework.beans.factory.xml.DefaultNamespaceHandlerResolver.resolve(DefaultNamespaceHandlerResolver.java:139)
	at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1330)
	at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1325)
	at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.parseBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:135)
	at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.registerBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:93)
	at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.registerBeanDefinitions(XmlBeanDefinitionReader.java:493)
	at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:390)
	... 30 more
Caused by: java.lang.NoClassDefFoundError: javax/xml/bind/JAXBException
	at org.apache.cxf.jaxrs.spring.NamespaceHandler.init(NamespaceHandler.java:26)
	at org.springframework.beans.factory.xml.DefaultNamespaceHandlerResolver.resolve(DefaultNamespaceHandlerResolver.java:130)
	... 36 more
Caused by: java.lang.ClassNotFoundException: javax.xml.bind.JAXBException
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(Unknown Source)
	at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(Unknown Source)
	at java.base/java.lang.ClassLoader.loadClass(Unknown Source)
	at org.eclipse.jetty.webapp.WebAppClassLoader.loadClass(WebAppClassLoader.java:560)
	at java.base/java.lang.ClassLoader.loadClass(Unknown Source)
	... 38 more
[2018-01-24 22:48:42.106 ERROR] [main  web.context.ContextLoader:220] - Context initialization failed

简单看了下，jaxb找不到，印象中jaxb是有一个独立的工程，但是jse也集成了。试着额外加载jaxb的mvn库，继续报其他web相关的类WebServiceContext找不到。分析了很久，这个就没有可以替代的。感觉不对劲，Google了半天，找到了这个链接：https://stackoverflow.com/questions/43574426/how-to-resolve-java-lang-noclassdeffounderror-javax-xml-bind-jaxbexception-in-j。Java 9 模块化把javax相关的包都默认禁止访问了，需要添加额外的启动参数才能访问。 修改start.bat，添加

--add-modules java.xml.bind,java.xml.ws,java.xml.ws.annotation

后问题解决：

@ cd /d %~dp0 
java --add-modules java.xml.bind,java.xml.ws,java.xml.ws.annotation -Xms512M -Xmx512M -Xdebug -Xrunjdwp:transport=dt_socket,address=4321,server=y,suspend=n -jar start.jar pause 

要彻底解决这个问题还不是一件简单的事情，因为其它的jdk版本不支持此参数，不能默认都添加。得在启动脚本中识别运行时的jre环境，分析java版本，只有在java9下才添加该参数。更为麻烦的是，还要考虑各个不同的厂商的版本version号的规则不一样。如OpenJDK和Oracle的命名就不完全一样。模块化挺好的，但是破坏兼容性，Java 9 这事儿干得真不明智。