java - 类加载器在 Tomcat 6 中加载库问题

Question

我正在尝试为 Jira 编写一个新的监听器，但我遇到了一个问题，非常感谢您提供的帮助和指导。

背景我们在 Apache Tomcat 下运行 Jira 4.2.2 Enterprise WAR。这包括 webapps/jira/WEB-INF/lib 下的以下 jar 文件:

* slf4j-api-1.5.8.jar
* slf4j-log4j12-1.5.8.jar

我们有一个作为插件运行的简单类。它接收事件并根据事件类型做一些工作。此类使用 slf4j 进行日志记录并按预期工作。该类被打包到一个 jar 中并部署在 webapps/jira/WEB-INF/lib 下并从那里使用。我们可以将其添加为监听器，对其进行配置并在日志中查看初始化消息。所有日志记录都通过 slf4j 进行并有效。

当我们尝试从第 3 方库向我们的插件添加功能时，我们收到以下异常:com.atlassian.util.concurrent.LazyReference$InitializationException:java.lang.NoClassDefFoundError:org/slf4j/LoggerFactory

由于 slf4j 可用并由我们从中调用此第 3 方库的类使用，我不明白我做错了什么或如何在调用时使其可用。

工作案例

在我们的代码中，我们创建了一个记录器，如下所示:

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.3rdparty.login;
public class JiraSampleListener extends AbstractIssueEventListener implements IssueEventListener {
    private final static Logger logger = LoggerFactory.getLogger(JiraSampleListener.class);
    .
    .
    .

然后我们可以通过调用来使用它

logger.warn("MESSAGE")

预期的消息出现在我们的日志中。

错误案例

只要我们将以下代码添加到此类，我们就会收到附加的异常:

newThing = new 3rdPartyClass("name of thing");

异常

com.atlassian.util.concurrent.LazyReference$InitializationException: java.lang.NoClassDefFoundError: org/slf4j/LoggerFactory

任何关于解决此问题的建议或指出我在这里做错的地方都将不胜感激!

异常的更完整 View 如下...

2011-01-19 05:30:51,016 main ERROR      [com.atlassian.jira.ComponentManager] Error occurred while starting component 'com.atlassian.jira.event.DefaultListenerManager'.com.atlassian.util.concurrent.LazyReference$InitializationException: java.lang.NoClassDefFoundError: org/slf4j/LoggerFactory        at com.atlassian.util.concurrent.LazyReference.getInterruptibly(LazyReference.java:148)        at com.atlassian.util.concurrent.LazyReference.get(LazyReference.java:111)        at com.atlassian.util.concurrent.ResettableLazyReference.get(ResettableLazyReference.java:89)        at com.atlassian.jira.event.DefaultListenerManager$Listeners.start(DefaultListenerManager.java:93)        at com.atlassian.jira.event.DefaultListenerManager.start(DefaultListenerManager.java:38)        at com.atlassian.jira.ComponentManager.quickStart(ComponentManager.java:256)        at com.atlassian.jira.ComponentManager.start(ComponentManager.java:212)        at com.atlassian.jira.upgrade.ConsistencyLauncher.launchConsistencyChecker(ConsistencyLauncher.java:63)        at com.atlassian.jira.upgrade.ConsistencyLauncher.contextInitialized(ConsistencyLauncher.java:42)        at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:3972)        at org.apache.catalina.core.StandardContext.start(StandardContext.java:4467)        at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:791)        at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:771)        at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:546)        at org.apache.catalina.startup.HostConfig.deployDescriptor(HostConfig.java:637)        at org.apache.catalina.startup.HostConfig.deployDescriptors(HostConfig.java:563)        at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:498)        at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1277)        at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:321)        at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)        at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1053)        at org.apache.catalina.core.StandardHost.start(StandardHost.java:785)        at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)        at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:443)        at org.apache.catalina.core.StandardService.start(StandardService.java:519)        at org.apache.catalina.core.StandardServer.start(StandardServer.java:710)        at org.apache.catalina.startup.Catalina.start(Catalina.java:581)        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)        at java.lang.reflect.Method.invoke(Method.java:597)        at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289)        at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414)Caused by: java.lang.NoClassDefFoundError: org/slf4j/LoggerFactory        at 3rd.party.3rdPartyClassDefaultImpl.(3rdPartyClassDefaultImpl.java:101)        at java.lang.Class.forName0(Native Method)        at java.lang.Class.forName(Class.java:169)        at 3rd.party.3rdParty.(3rdParty.java:107)        at 3rd.party.3rdParty.(3rdParty.java:83)        at 3rd.party.3rdParty.(3rdParty.java:67)        at my.organisationlisteners.JiraSampleListener.init(JiraSampleListener.java:36)        at com.atlassian.jira.event.ListenerFactory.getListener(ListenerFactory.java:33)        at com.atlassian.jira.event.DefaultListenerManager$Listeners.loadListeners(DefaultListenerManager.java:126)        at com.atlassian.jira.event.DefaultListenerManager$Listeners.create(DefaultListenerManager.java:71)        at com.atlassian.jira.event.DefaultListenerManager$Listeners.create(DefaultListenerManager.java:66)        at com.atlassian.util.concurrent.ResettableLazyReference$InternalReference.create(ResettableLazyReference.java:143)        at com.atlassian.util.concurrent.LazyReference$Sync.run(LazyReference.java:316)        at com.atlassian.util.concurrent.LazyReference.getInterruptibly(LazyReference.java:142)        ... 32 moreCaused by: java.lang.ClassNotFoundException: org.slf4j.LoggerFactory        at java.net.URLClassLoader$1.run(URLClassLoader.java:202)        at java.security.AccessController.doPrivileged(Native Method)        at java.net.URLClassLoader.findClass(URLClassLoader.java:190)        at java.lang.ClassLoader.loadClass(ClassLoader.java:307)        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)        at java.lang.ClassLoader.loadClass(ClassLoader.java:248)        ... 46 more

Answer 1

Caused by: java.lang.NoClassDefFoundError: org/slf4j/LoggerFactory at              
3rd.party.3rdPartyClassDefaultImpl.(3rdPartyClassDefaultImpl.java:101) at         
java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Class.java:169) at 
3rd.party.3rdParty.(3rdParty.java:107) at 3rd.party.3rdParty.(3rdParty.java:83) at 
3rd.party.3rdParty.(3rdParty.java:67) at 

这意味着您的类 3rdPartyClassDefaultImpl 找不到 LoggerFactory。这个第三方库位于 CATALINA_HOME\lib 下吗？如果是这样，则意味着它由“通用类加载器”( classloaders in tomcat ) 加载，并且所有必需的类 (3rdPartyClassDefaultImpl, LoggerFactory) 在它或父级的类存储库中被搜索，但找不到。

可能的解决方案之一是将 thirparty.jar 放在 web-inf/lib 下或将 slf4j 和 log4jwrapper 移动到 CATALINA_HOME\LIB