如何在Tomcat9.0.12中将堆栈跟踪输入到控制台?
我参考了https://ameblo.jp/ill-grasper/entry-11173169674.html这篇文章。
由于在Tomcat9和JVM8的默认组合下，堆栈跟踪没有输出到Eclipse控制台，所以我根据上述文章尝试了我的环境并记录了结果。
测试servlet的代码
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
PrintWriter out = response.getWriter();
out.println("Hello");
throw new ServletException();
}
刻意放置的logging.properties。解压Tomcat的zip文件后，默认情况下不需要编辑。
下面是解决因log4j设置问题导致Tomcat启动失败的方法。
※要复现以下类似的错误花费了很大的努力。。。
07-Apr-2022 22:00:58.667 重大 [main] org.apache.catalina.startup.Catalina.start The required Server component failed to start so Tomcat is unable to start.
org.apache.catalina.LifecycleException: A child container failed during start
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:960)
at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:261)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.core.StandardService.startInternal(StandardService.java:422)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:770)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.startup.Catalina.start(Catalina.java:682)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:350)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:492)
Caused by: java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: A child container failed during start
at java.util.concurrent.FutureTask.report(FutureTask.java:122)
at java.util.concurrent.FutureTask.get(FutureTask.java:192)
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:951)
... 13 more
Caused by: org.apache.catalina.LifecycleException: A child container failed during start
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:960)
at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:839)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1429)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1419)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at org.apache.tomcat.util.threads.InlineExecutorService.execute(InlineExecutorService.java:75)
at java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:134)
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:944)
... 13 more
Caused by: java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/TomcatTest]]
at java.util.concurrent.FutureTask.report(FutureTask.java:122)
at java.util.concurrent.FutureTask.get(FutureTask.java:192)
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:951)
... 21 more
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/TomcatTest]]
at org.apache.catalina.util.LifecycleBase.handleSubClassException(LifecycleBase.java:441)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:198)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1429)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1419)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at org.apache.tomcat.util.threads.InlineExecutorService.execute(InlineExecutorService.java:75)
at java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:134)
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:944)
... 21 more
Caused by: java.lang.NoClassDefFoundError: Lorg/apache/log4j/Logger;
at java.lang.Class.getDeclaredFields0(Native Method)
at java.lang.Class.privateGetDeclaredFields(Class.java:2583)
at java.lang.Class.getDeclaredFields(Class.java:1916)
at org.apache.catalina.util.Introspection.getDeclaredFields(Introspection.java:110)
at org.apache.catalina.startup.WebAnnotationSet.loadFieldsAnnotation(WebAnnotationSet.java:269)
at org.apache.catalina.startup.WebAnnotationSet.loadApplicationServletAnnotations(WebAnnotationSet.java:137)
at org.apache.catalina.startup.WebAnnotationSet.loadApplicationAnnotations(WebAnnotationSet.java:69)
at org.apache.catalina.startup.ContextConfig.applicationAnnotationsConfig(ContextConfig.java:328)
at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:768)
at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:299)
at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:123)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5007)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
... 27 more
Caused by: java.lang.ClassNotFoundException: org.apache.log4j.Logger
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1309)
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1138)
... 40 more
应对措施
将log4j的jar文件复制到Tomcat主目录下的lib文件夹中，就像上面所述的那样。
将log4j.properties文件放置在WEB-INF\classes目录中。
为了测试目的，进行简单的设置。
log4j.rootCategory=DEBUG, Appender1
log4j.appender.Appender1=org.apache.log4j.ConsoleAppender
log4j.appender.Appender1.layout=org.apache.log4j.PatternLayout
log4j.appender.Appender1.layout.ConversionPattern=%d{yyyy/MM/dd HH:mm:ss.SSS} [%t] %-6p %m%n
Servlet的源代码如下所示。
import org.apache.log4j.Logger;
@WebServlet("/TestServlet")
public class TestServlet extends HttpServlet {
private Logger log = Logger.getLogger(TestServlet.class);
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
log.info("log4jテスト");
PrintWriter out = response.getWriter();
out.println("Hello");
}
