【发布时间】：2015-11-18 02:18:12
【问题描述】：
我创建了一个带有一些 html 页面的简单 servlet 动态项目，......
由于单击表单上的提交按钮应该将控件转移到servlet，我不知道是什么问题，它显示“HTTP status 500”错误.... 它显示错误为：
浏览器出现异常： java.lang.NullPointerException 控制器.Trafcontrol.doGet(Trafcontrol.java:48) javax.servlet.http.HttpServlet.service(HttpServlet.java:690) javax.servlet.http.HttpServlet.service(HttpServlet.java:803) org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
使用的应用服务器：JBOSS AS 4.2.2，Eclipse：Helios 3.6..
我需要将我的控制权传递给 servlet，以便我可以进一步处理我的项目。
我还包括“控制台”窗口内容：
`Servlet.service() for servlet servname threw exception
java.lang.NullPointerException
at controller.Trafcontrol.doGet(Trafcontrol.java:48)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:690)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:230)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:182)
at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:84)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:157)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:262)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
at
org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583) 在 org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:446) 在 java.lang.Thread.run(Unknown Source)`
请任何人帮忙，谢谢.....
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