omcat无法启动，报如下错误：

 严重: A child container failed during start

 java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[]]

 at java.util.concurrent.FutureTask.report(Unknown Source)

 at java.util.concurrent.FutureTask.get(Unknown Source)

 at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1119)

 at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:819)

 at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147)

 at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1571)

 at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1561)

 at java.util.concurrent.FutureTask.run(Unknown Source)

 at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)

 at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)

 at java.lang.Thread.run(Unknown Source)

 Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[]]

 at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:153)

 ... 6 more

 Caused by: java.lang.NoClassDefFoundError: Lorg/apache/commons/logging/Log;

 at java.lang.Class.getDeclaredFields0(Native Method)

 at java.lang.Class.privateGetDeclaredFields(Unknown Source)

 at java.lang.Class.getDeclaredFields(Unknown Source)

 at org.apache.catalina.util.Introspection.getDeclaredFields(Introspection.java:106)

 at org.apache.catalina.startup.WebAnnotationSet.loadFieldsAnnotation(WebAnnotationSet.java:270)

 at org.apache.catalina.startup.WebAnnotationSet.loadApplicationServletAnnotations(WebAnnotationSet.java:139)

 at org.apache.catalina.startup.WebAnnotationSet.loadApplicationAnnotations(WebAnnotationSet.java:65)

 at org.apache.catalina.startup.ContextConfig.applicationAnnotationsConfig(ContextConfig.java:416)

 at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:890)

 at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:387)

 at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:117)

 at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:90)

 at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5503)

 at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147)

 ... 6 more

 Caused by: java.lang.ClassNotFoundException: org.apache.commons.logging.Log

 at java.net.URLClassLoader$1.run(Unknown Source)

 at java.net.URLClassLoader$1.run(Unknown Source)

 at java.security.AccessController.doPrivileged(Native Method)

 at java.net.URLClassLoader.findClass(Unknown Source)

 at java.lang.ClassLoader.loadClass(Unknown Source)

 at java.lang.ClassLoader.loadClass(Unknown Source)

 ... 20 more

      <dependency>

            <groupId>commons-logging</groupId>

            <artifactId>commons-logging-api</artifactId>

            <version>1.1</version>

        </dependency>