获取org.apache.jasper.JasperException：java.lang.NullPointerException

Question

这是我的基于Java Struts的Web应用程序和webRoot目录的目录结构。

代码已成功编译，但当我将其运行到浏览器时，它会给出HTTP状态500的异常：

org.apache.jasper.JasperException: java.lang.NullPointerException
    org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:541)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:375)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:803)


root cause 

java.lang.NullPointerException
    org.apache.jsp.index_jsp._jspInit(index_jsp.java:22)
    org.apache.jasper.runtime.HttpJspBase.init(HttpJspBase.java:52)
    org.apache.jasper.servlet.JspServletWrapper.getServlet(JspServletWrapper.java:159)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:329)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:803)

请允许任何人帮助我，请提前致谢。

我尝试使用war文件来运行外部tomcat-7但显示相同的错误，也发现了这个org.apache.jasper.JasperException: java.lang.NullPointerException但对我没有帮助。

这是web.xml

<?xml version="1.0"?>
<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
                         "http://java.sun.com/dtd/web-app_2_3.dtd">
<web-app>
 <display-name>Ilex Reports</display-name>
 <description>Report Server</description>
 <servlet>
  <servlet-name>rpt</servlet-name>
  <servlet-class>org.apache.struts.action.ActionServlet</servlet-class>
  <init-param>
   <param-name>config</param-name>
   <param-value>/WEB-INF/struts-config.xml</param-value>
  </init-param>
  <init-param>
   <param-name>host</param-name>
   <param-value>localhost</param-value>
  </init-param>
  <init-param>
   <param-name>port</param-name>
   <param-value>80</param-value>
  </init-param>
 </servlet>
 <servlet-mapping>
  <servlet-name>rpt</servlet-name>
  <url-pattern>*.xo</url-pattern>
 </servlet-mapping>
 <welcome-file-list>
  <welcome-file>/index.jsp</welcome-file>
 </welcome-file-list>
 <!-- Custom Tag Library Descriptors -->
 <taglib>
  <taglib-uri>http://jakarta.apache.org/tomcat/fb-taglib</taglib-uri>
  <taglib-location>/WEB-INF/tld/Element.tld</taglib-location>
 </taglib>
 <!-- Struts Tag Library Descriptors -->
 <taglib>
  <taglib-uri>/tags/struts-bean</taglib-uri>
  <taglib-location>/WEB-INF/tld/struts-bean.tld</taglib-location>
 </taglib>
 <taglib>
  <taglib-uri>/tags/struts-html</taglib-uri>
  <taglib-location>/WEB-INF/tld/struts-html.tld</taglib-location>
 </taglib>
 <taglib>
  <taglib-uri>/tags/struts-logic</taglib-uri>
  <taglib-location>/WEB-INF/tld/struts-logic.tld</taglib-location>
 </taglib>
 <taglib>
  <taglib-uri>/tags/struts-nested</taglib-uri>
  <taglib-location>/WEB-INF/tld/struts-nested.tld</taglib-location>
 </taglib>
 <taglib>
  <taglib-uri>/tags/struts-tiles</taglib-uri>
  <taglib-location>/WEB-INF/tld/struts-tiles.tld</taglib-location>
 </taglib>
 <login-config>
  <auth-method>BASIC</auth-method>
 </login-config>
</web-app>

Answer 1

做一件事，jsps被编译成java servlet，所以你可以检查代码并查看相应的行。我想是在tomcat的工作目录中的java文件。

错误行

org.apache.jsp.index_jsp._jspInit(index_jsp.java:22)

这是要查看的文件。

index_jsp.java

Answer 2

您可能会遇到版本不匹配，库版本不正确或者早期的损坏/部分JSP编译。

在我的系统＆amp;上查看Tomcat /工作目录（C：\ Dev \ Tomcat 6.0.35 \ work \ Catalina \ localhost \ jr \ org \ apache \ jsp \ WEB_002dINF \ jsp）。你可以看到index_jsp.java文件的源代码。

清理Tomcat / work目录以强制重新编译所有JSP。

从Tomcat 6开始，示例JSP中的_jspInit（）看起来像：

public void _jspInit() {
    _005fjspx_005ftagPool_005fc_005fout_0026_005fvalue_005fnobody = org.apache.jasper.runtime.TagHandlerPool.getTagHandlerPool(getServletConfig());
    _005fjspx_005ftagPool_005fc_005furl_0026_005fvalue_005fnobody = org.apache.jasper.runtime.TagHandlerPool.getTagHandlerPool(getServletConfig());
    _005fjspx_005ftagPool_005fc_005fout_0026_005fvalue_005fescapeXml_005fnobody = org.apache.jasper.runtime.TagHandlerPool.getTagHandlerPool(getServletConfig());
    _el_expressionfactory = _jspxFactory.getJspApplicationContext(getServletConfig().getServletContext()).getExpressionFactory();
    _jsp_annotationprocessor = (org.apache.AnnotationProcessor) getServletConfig().getServletContext().getAttribute(org.apache.AnnotationProcessor.class.getName());
}

基本上，这些东西应该有效 - 所以你的配置几乎肯定存在问题。