使WEB-INF/LIB中的Tomcat忽略Servlet [英] Make Tomcat Ignore Servlet in WEB-INF/LIB

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本文介绍了使WEB-INF/LIB中的Tomcat忽略Servlet的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我创建了一个Web应用程序，我需要它能够与图形数据库进行交互(我正在使用Titan).当添加Titan的依赖关系时，尝试在Tomcat中部署此WAR时出现以下错误:

I'm created a web-application and I need it to be able to interact with a graph database (I'm using Titan). When adding Titan's dependency, I get the following errors when I try to deploy this WAR in Tomcat:

SEVERE: A child container failed during start
java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Tomcat].StandardHost[localhost].StandardContext[]]
    at java.util.concurrent.FutureTask.report(FutureTask.java:122)
    at java.util.concurrent.FutureTask.get(FutureTask.java:188)
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1123)
    at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:800)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549)
    at java.util.concurrent.FutureTask.run(FutureTask.java:262)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:744)
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Tomcat].StandardHost[localhost].StandardContext[]]
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154)
    ... 6 more
Caused by: java.lang.LinkageError: loader constraint violation: loader (instance of org/apache/catalina/loader/WebappClassLoader) previously initiated loading for a different type with name "javax/servlet/ServletContext"
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
    at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
    at org.apache.catalina.loader.WebappClassLoader.findClass(WebappClassLoader.java:1191)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1669)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1547)
    at org.springframework.web.SpringServletContainerInitializer.onStartup(SpringServletContainerInitializer.java:173)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5423)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    ... 6 more

Jan 24, 2014 11:43:04 AM org.apache.catalina.core.ContainerBase startInternal
SEVERE: A child container failed during start
java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Tomcat].StandardHost[localhost]]
    at java.util.concurrent.FutureTask.report(FutureTask.java:122)
    at java.util.concurrent.FutureTask.get(FutureTask.java:188)
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1123)
    at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:302)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    at org.apache.catalina.core.StandardService.startInternal(StandardService.java:443)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:732)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    at org.apache.catalina.startup.Tomcat.start(Tomcat.java:341)
    at org.apache.tomcat.maven.plugin.tomcat7.run.AbstractRunMojo.startContainer(AbstractRunMojo.java:1238)
    at org.apache.tomcat.maven.plugin.tomcat7.run.AbstractRunMojo.execute(AbstractRunMojo.java:592)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:101)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:209)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:84)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:59)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.singleThreadedBuild(LifecycleStarter.java:183)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:161)
    at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:320)
    at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:156)
    at org.apache.maven.cli.MavenCli.execute(MavenCli.java:537)
    at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:196)
    at org.apache.maven.cli.MavenCli.main(MavenCli.java:141)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:290)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:230)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:409)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:352)
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Tomcat].StandardHost[localhost]]
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549)
    at java.util.concurrent.FutureTask.run(FutureTask.java:262)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:744)
Caused by: org.apache.catalina.LifecycleException: A child container failed during start
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1131)
    at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:800)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    ... 6 more

一些进一步的研究使我发现Titan不包括一个，而是包括两个servlet-api-2.5.jar文件.我知道，当将servlet罐子放在WEB-INF/lib中并且假设这是问题的根源时，Tomcat不会感激它.有两种可能的解决方案:

Some further research has led me to find that Titan is including not one, but two servlet-api-2.5.jar files. I know that Tomcat does not appreciate it when servlet jars are placed in WEB-INF/lib and am assuming that this is the root of the problem. There are two potential solutions to this:

  • 让Titan可以在Tomcat中使用servlet jar

  • Make Titan to use the servlet jar within Tomcat

告诉Tomcat忽略WEB-INF/lib中的servlet jar.

Tell Tomcat to ignore the servlet jar in WEB-INF/lib.

但是，我不知道该怎么做.谁能指出我正确的方向?

However, I don't know how to do either of these things. Can anyone point me in the right direction?

此外，根据第一个可能的解决方案，我尝试将以下内容添加到我的Maven pom.xml中:

Additionally, per the first potential solution, I tried to add the following to my Maven pom.xml:

<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>servlet-api</artifactId>
    <version>2.5</version>
    <scope>provided</scope>
</dependency>

但是，Titan仍然包括它自己的Java servlet版本.

But, Titan still included it's own version of the java servlet.

推荐答案

将servlet声明为provided

Declare servlet as provided

<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>servlet-api</artifactId>
    <version>2.5</version>
    <scope>provided</scope>
</dependency>

或

<dependency>
    <groupId>org.mortbay.jetty</groupId> 
    <artifactId>servlet-api</artifactId> 
    <version>2.5-20081211</version>
    <scope>provided</scope>
</dependency>

并从titan中排除servlet

and exclude servlet from titan

<dependency>
   <groupId>titan</groupId>
   <artifactId>titan</artifactId>
   <exclusions>
      <exclusion>
         <groupId>javax.servlet</groupId>
         <artifactId>servlet-api</artifactId>
      </exclusion>
   </exclusions>
</dependency>

这篇关于使WEB-INF/LIB中的Tomcat忽略Servlet的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！

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