帮帮忙了，我是初学者在学习Struts2时关于文件上传时的错误，不知道怎么去改了，让我花费一下午的时间还是不对，一直提示我配置不对

2012-12-6 17:44:42 com.opensymphony.xwork2.util.logging.commons.CommonsLogger info

信息: Unable to find 'struts.multipart.saveDir' property setting. Defaulting to javax.servlet.context.tempdir

2012-12-6 17:44:42 org.apache.catalina.core.StandardWrapperValve invoke

严重: Servlet.service() for servlet [default] in context with path [/DTO] threw exception [Filter execution threw an exception] with root cause

java.lang.Error: Unresolved compilation problems:

The type javax.servlet.ServletContext cannot be resolved. It is indirectly referenced from required .class files

The method getServletContext() from the type ServletActionContext refers to the missing type ServletContext

at actions.LoginAction.<init>(LoginAction.java:112)

at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)

at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)

at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)

at java.lang.reflect.Constructor.newInstance(Constructor.java:513)

at java.lang.Class.newInstance0(Class.java:355)

at java.lang.Class.newInstance(Class.java:308)

at com.opensymphony.xwork2.ObjectFactory.buildBean(ObjectFactory.java:119)

at com.opensymphony.xwork2.ObjectFactory.buildBean(ObjectFactory.java:150)

at com.opensymphony.xwork2.ObjectFactory.buildBean(ObjectFactory.java:139)

at com.opensymphony.xwork2.ObjectFactory.buildAction(ObjectFactory.java:109)

at com.opensymphony.xwork2.DefaultActionInvocation.createAction(DefaultActionInvocation.java:288)

at com.opensymphony.xwork2.DefaultActionInvocation.init(DefaultActionInvocation.java:388)

at com.opensymphony.xwork2.DefaultActionProxy.prepare(DefaultActionProxy.java:187)

at org.apache.struts2.impl.StrutsActionProxy.prepare(StrutsActionProxy.java:61)

at org.apache.struts2.impl.StrutsActionProxyFactory.createActionProxy(StrutsActionProxyFactory.java:39)

at com.opensymphony.xwork2.DefaultActionProxyFactory.createActionProxy(DefaultActionProxyFactory.java:47)

at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:478)

at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)

at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:91)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)

at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)

at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)

at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)

at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)

at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)

at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:929)

at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)

at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)

at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1002)

at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:585)

at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:1813)

at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)

at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)

at java.lang.Thread.run(Thread.java:619)