报错org.apache.catalina.LifecycleException caused by java.lang.NoSuchMethodError: javax.servlet.ServletContext.getClassLoader()Ljava/lang/ClassLoader

今天将tomcat6更换成了tomcat7,报错的内容

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[/webandroid]]
 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[/webandroid]]
 at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:153)
 ... 6 more
Caused by: java.lang.NoSuchMethodError: javax.servlet.ServletContext.getClassLoader()Ljava/lang/ClassLoader;
 at org.apache.catalina.startup.WebappServiceLoader.load(WebappServiceLoader.java:96)
 at org.apache.catalina.startup.ContextConfig.processServletContainerInitializers(ContextConfig.java:1573)
 at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1279)
 at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:887)
 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

解决方法:java的jre里面lib/ext/文件夹的

el-api.jar servlet-api.jar jsp-api.jar 需要更换成新的tomcat7里面的lib