的web.xml + JSP文件，如，Servlet

我试图使用Dfine我的JSP文件中的web.xml里面一个servlet：的web.xml + JSP文件，如，Servlet

<servlet> 
     <servlet-name>help.jsp</servlet-name> 
     <jsp-file>/Help.jsp</jsp-file> 
</servlet> 
<servlet-mapping> 
     <servlet-name>help.jsp</servlet-name> 
     <url-pattern>/Help</url-pattern> 
</servlet-mapping>

但Java给了我一个例外：

SEVERE: Servlet.service() for servlet [help.jsp] in context with path [/TestsJS] threw exception [java.lang.NullPointerException] with root cause 
java.lang.NullPointerException 
    at org.apache.jsp.Help_jsp._jspService(Help_jsp.java:320) 
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70) 
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) 
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432) 
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390) 
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334) 
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) 
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305) 
    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$AbstractConnectionHandler.process(AbstractProtocol.java:585) 
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310) 
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) 
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) 
    at java.lang.Thread.run(Unknown Source) 

дек 20, 2012 9:46:08 PM org.apache.catalina.core.StandardWrapperValve invoke 
SEVERE: Servlet.service() for servlet [help.jsp] in context with path [/TestsJS] threw exception [java.lang.NullPointerException] with root cause 
java.lang.NullPointerException 
    at org.apache.jsp.Help_jsp._jspService(Help_jsp.java:320) 
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70) 
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) 
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432) 
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390) 
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334) 
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) 
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305) 
    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$AbstractConnectionHandler.process(AbstractProtocol.java:585) 
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310) 
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) 
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) 
    at java.lang.Thread.run(Unknown Source)

我的Help.jsp位于项目根文件夹（“Projec/Help.jsp”）中。也许我应该把它放在别的地方？谢谢！

来源

2012-12-20 Andrey Yaskulsky

没有太多的机会可以在没有查看JSP源代码的情况下帮助你。 – mindas

JSP处于正确位置且web.xml正确。但是，您的JSP本身存在错误。

来源

2013-04-17 10:03:37

的web.xml + JSP文件，如，Servlet

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