web.xml配置init-param导致Tomcat9 JAX-RS应用服务404求助

在基于Tomcat9、Java JAX-RS（使用Jersey的org.glassfish.jersey.servlet.ServletContainer）的应用中，发现只要在web.xml的Servlet配置里加入<init-param>标签，/services/*路径就会返回404；移除该标签后，http://localhost:8081/app/services/whatever可以正常访问。

相关web.xml配置 #

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"
         xmlns="http://java.sun.com/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
    http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
  <display-name>Test</display-name>
  <servlet>
    <display-name>JAX-RS REST Servlet</display-name>
    <servlet-name>JAX-RS REST Servlet</servlet-name>
    <servlet-class>
      org.glassfish.jersey.servlet.ServletContainer
    </servlet-class>
    <init-param>
      <param-name>parname</param-name>
      <param-value>parval</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>JAX-RS REST Servlet</servlet-name>
    <url-pattern>/services/*</url-pattern>
  </servlet-mapping>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>

日志对比及疑问 #

对比有无init-param时的Catalina日志，除时间戳外无其他差异。同时日志中出现了java.lang.ClassCastException，不确定是否和当前问题相关。

含init-param时的Catalina日志 #

05-Apr-2023 11:04:47.923 INFO [Catalina-utility-1] org.apache.catalina.startup.HostConfig.undeploy Undeploying context [/testDevOps]
05-Apr-2023 11:04:47.933 WARNING [Catalina-utility-1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesObjectStreamClassCaches Failed to clear soft references from ObjectStreamClass$Caches for web application [testDevOps]
    java.lang.ClassCastException: class java.io.ObjectStreamClass$Caches$1 cannot be cast to class java.util.Map (java.io.ObjectStreamClass$Caches$1 and java.util.Map are in module java.base of loader 'bootstrap')
      at org.apache.catalina.loader.WebappClassLoaderBase.clearCache(WebappClassLoaderBase.java:2325)
      at org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesObjectStreamClassCaches(WebappClassLoaderBase.java:2300)
      at org.apache.catalina.loader.WebappClassLoaderBase.clearReferences(WebappClassLoaderBase.java:1669)
      at org.apache.catalina.loader.WebappClassLoaderBase.stop(WebappClassLoaderBase.java:1597)
      at org.apache.catalina.loader.WebappLoader.stopInternal(WebappLoader.java:463)
      at org.apache.catalina.util.LifecycleBase.stop(LifecycleBase.java:257)
      at org.apache.catalina.core.StandardContext.stopInternal(StandardContext.java:5515)
      at org.apache.catalina.util.LifecycleBase.stop(LifecycleBase.java:257)
      at org.apache.catalina.core.ContainerBase.removeChild(ContainerBase.java:814)
      at org.apache.catalina.startup.HostConfig.undeploy(HostConfig.java:1466)
      at org.apache.catalina.startup.HostConfig.checkResources(HostConfig.java:1391)
      at org.apache.catalina.startup.HostConfig.check(HostConfig.java:1654)
      at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:315)
      at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:123)
      at org.apache.catalina.core.ContainerBase.backgroundProcess(ContainerBase.java:1162)
      at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1365)
      at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1369)
      at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1347)
      at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
      at java.base/java.util.concurrent.FutureTask.runAndReset(FutureTask.java:305)
      at java.base/java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:305)
      at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
      at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
      at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
      at java.base/java.lang.Thread.run(Thread.java:829)
05-Apr-2023 11:04:51.828 INFO [http-nio-8081-exec-7] org.apache.catalina.startup.HostConfig.deployWAR Deploying web application archive [/var/lib/tomcat9/webapps/testDevOps.war]
05-Apr-2023 11:04:52.340 INFO [http-nio-8081-exec-7] org.apache.jasper.servlet.TldScanner.scanJars At least one JAR was scanned for TLDs yet contained no TLDs. Enable debug logging for this logger for a complete list of JARs that were scanned but no TLDs were found in them. Skipping unneeded JARs during scanning can improve startup time and JSP compilation time.
05-Apr-2023 11:04:52.439 WARNING [http-nio-8081-exec-7] org.glassfish.jersey.message.internal.MessagingBinders$EnabledProvidersBinder.bindToBinder A class javax.activation.DataSource for a default provider MessageBodyWriter<javax.activation.DataSource> was not found. The provider is not available.
05-Apr-2023 11:04:52.448 WARNING [http-nio-8081-exec-7] org.glassfish.jersey.server.wadl.WadlFeature.configure JAX-B API not found . WADL feature is disabled.
05-Apr-2023 11:04:52.500 INFO [http-nio-8081-exec-7] org.apache.catalina.startup.HostConfig.deployWAR Deployment of web application archive [/var/lib/tomcat9/webapps/testDevOps.war] has finished in [673] ms

不含init-param时的Catalina日志 #

05-Apr-2023 11:06:38.449 INFO [Catalina-utility-1] org.apache.catalina.startup.HostConfig.undeploy Undeploying context [/testDevOps]
05-Apr-2023 11:06:38.460 WARNING [Catalina-utility-1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesObjectStreamClassCaches Failed to clear soft references from ObjectStreamClass$Caches for web application [testDevOps]
    java.lang.ClassCastException: class java.io.ObjectStreamClass$Caches$1 cannot be cast to class java.util.Map (java.io.ObjectStreamClass$Caches$1 and java.util.Map are in module java.base of loader 'bootstrap')
      at org.apache.catalina.loader.WebappClassLoaderBase.clearCache(WebappClassLoaderBase.java:2325)
      at org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesObjectStreamClassCaches(WebappClassLoaderBase.java:2300)
      at org.apache.catalina.loader.WebappClassLoaderBase.clearReferences(WebappClassLoaderBase.java:1669)
      at org.apache.catalina.loader.WebappClassLoaderBase.stop(WebappClassLoaderBase.java:1597)
      at org.apache.catalina.loader.WebappLoader.stopInternal(WebappLoader.java:463)
      at org.apache.catalina.util.LifecycleBase.stop(LifecycleBase.java:257)
      at org.apache.catalina.core.StandardContext.stopInternal(StandardContext.java:5515)
      at org.apache.catalina.util.LifecycleBase.stop(LifecycleBase.java:257)
      at org.apache.catalina.core.ContainerBase.removeChild(ContainerBase.java:814)
      at org.apache.catalina.startup.HostConfig.undeploy(HostConfig.java:1466)
      at org.apache.catalina.startup.HostConfig.checkResources(HostConfig.java:1391)
      at org.apache.catalina.startup.HostConfig.check(HostConfig.java:1654)
      at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:315)
      at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:123)
      at org.apache.catalina.core.ContainerBase.backgroundProcess(ContainerBase.java:1162)
      at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1365)
      at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1369)
      at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1347)
      at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
      at java.base/java.util.concurrent.FutureTask.runAndReset(FutureTask.java:305)
      at java.base/java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:305)
      at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
      at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
      at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
      at java.base/java.lang.Thread.run(Thread.java:829)
05-Apr-2023 11:06:39.945 INFO [http-nio-8081-exec-12] org.apache.catalina.startup.HostConfig.deployWAR Deploying web application archive [/var/lib/tomcat9/webapps/testDevOps.war]
05-Apr-2023 11:06:40.400 INFO [http-nio-8081-exec-12] org.apache.jasper.servlet.TldScanner.scanJars At least one JAR was scanned for TLDs yet contained no TLDs. Enable debug logging for this logger for a complete list of JARs that were scanned but no TLDs were found in them. Skipping unneeded JARs during scanning can improve startup time and JSP compilation time.
05-Apr-2023 11:06:40.506 WARNING [http-nio-8081-exec-12] org.glassfish.jersey.message.internal.MessagingBinders$EnabledProvidersBinder.bindToBinder A class javax.activation.DataSource for a default provider MessageBodyWriter<javax.activation.DataSource> was not found. The provider is not available.
05-Apr-2023 11:06:40.512 WARNING [http-nio-8081-exec-12] org.glassfish.jersey.server.wadl.WadlFeature.configure JAX-B API not found . WADL feature is disabled.
05-Apr-2023 11:06:40.594 INFO [http-nio-8081-exec-12] org.apache.catalina.startup.HostConfig.deployWAR Deployment of web application archive [/var/lib/tomcat9/webapps/testDevOps.war] has finished in [650] ms

排查建议 #

• 检查Jersey版本兼容性：旧版Jersey可能在处理自定义init-param时存在适配Tomcat9的问题，建议升级到Jersey 2.35及以上版本（适配Java 8+和Tomcat9的稳定分支）
• 替换自定义init-param为Jersey标准参数：比如添加jersey.config.server.provider.packages参数指定你的JAX-RS资源所在包路径，测试是否仍出现404，排除自定义参数名的干扰
• 开启Jersey调试日志：在Tomcat的logging.properties中添加org.glassfish.jersey.level = FINE，查看请求到达Servlet后的路由匹配细节，确认是否存在资源匹配失败的日志
• 验证Servlet初始化状态：添加ServletContextListener，在contextInitialized方法中打印Servlet的init参数，确认参数是否被正确加载
• 关于ClassCastException：该异常发生在web应用卸载阶段，属于Tomcat9在特定Java版本下的已知小问题，和当前请求404无关联，可忽略，不影响应用运行

内容的提问来源于stack exchange，提问作者lewap02