自己寫了個最簡單的springMVC項目練練手，沒有用maven，在WebContent中新建了lib文件夾，將jar包復制到這里面，然后add to build path到項目里。
啟動Tomcat，報錯，啟動不起來。在網頁中運行localhost:8080發現Tomcat頁面是可以打開的。
報錯內容如下：
1 嚴重: A child container failed during start 2 java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/zhang]] 3 at java.util.concurrent.FutureTask.report(FutureTask.java:122) 4 at java.util.concurrent.FutureTask.get(FutureTask.java:188) 5 at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1123) 6 at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:799) 7 at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) 8 at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559) 9 at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549) 10 at java.util.concurrent.FutureTask.run(FutureTask.java:262) 11 at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) 12 at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) 13 at java.lang.Thread.run(Thread.java:745) 14 Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/zhang]] 15 at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154) 16 ... 6 more 17 Caused by: java.lang.NoClassDefFoundError: org/springframework/web/context/WebApplicationContext 18 at java.lang.Class.getDeclaredFields0(Native Method) 19 at java.lang.Class.privateGetDeclaredFields(Class.java:2436) 20 at java.lang.Class.getDeclaredFields(Class.java:1806) 21 at org.apache.catalina.util.Introspection.getDeclaredFields(Introspection.java:106) 22 at org.apache.catalina.startup.WebAnnotationSet.loadFieldsAnnotation(WebAnnotationSet.java:261) 23 at org.apache.catalina.startup.WebAnnotationSet.loadApplicationServletAnnotations(WebAnnotationSet.java:140) 24 at org.apache.catalina.startup.WebAnnotationSet.loadApplicationAnnotations(WebAnnotationSet.java:65) 25 at org.apache.catalina.startup.ContextConfig.applicationAnnotationsConfig(ContextConfig.java:403) 26 at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:879) 27 at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:374) 28 at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:117) 29 at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:90) 30 at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5355) 31 at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) 32 ... 6 more 33 Caused by: java.lang.ClassNotFoundException: org.springframework.web.context.WebApplicationContext 34 at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1720) 35 at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571) 36 ... 20 more
網上百度大家都說是jar包缺少。但是檢查spring所需要的jar包，都存在，如下圖。
然后就看lib文件是不是有問題，果然有問題。
原來我的lib文件夾在WebContent下，將它放到WEB-INF目錄下，再重新將jar包add to build path里，項目就能啟動了。
現在將這個問題分享出來，希望能幫到其他的朋友。
可能我犯得這個錯誤很低級，別人不會犯這種錯誤吧。^_^