java.lang.NullPointerException at org.apache.jsp.index_jsp._jspInit(index_jsp.ja

java.lang.NullPointerExceptionatorg.apache.jsp.index_jsp._jspInit(index_jsp.ja

环境：Tomcat6+jdk6

Tomcat服务启动成功，但访问index.jsp出错，Tomcat报错如下:

严重:Servlet.service()forservletjspthrewexception

java.lang.NullPointerException

atorg.apache.jsp.index_jsp._jspInit(index_jsp.java:23)

atorg.apache.jasper.runtime.HttpJspBase.init(HttpJspBase.java:52)

atorg.apache.jasper.servlet.JspServletWrapper.getServlet(JspServletWrapper.java:159)

atorg.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:329)

atorg.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)

atorg.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)

atjavax.servlet.http.HttpServlet.service(HttpServlet.java:717)

atorg.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)

atorg.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)

atorg.apache.struts2.dispatcher.FilterDispatcher.doFilter(FilterDispatcher.java:389)

atorg.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)

atorg.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)

atorg.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)

atorg.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)

atorg.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)

atorg.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)

atorg.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)

atorg.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)

atorg.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:861)

atorg.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:579)

atorg.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1584)

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

最后找到原因：jsp-api.jar冲突。

jsp-api.jar冲突会造成jsp页面无法解析。

写自定义标签的时候请注意，在工程编译的时候可以引用jsp-api.jar，但发布的时候工程不要包含此包，因为Tomcat已包含。

用于开发，而不用于发布

解决方法1：UserLibrary

选中项目－－>右击－－>properties－－>JavaBuildPath－－>AddLibrary－－>选中UserLiberary－－>

Next－－>UserLibraries...－－>New－－>如下一定要选中：口SystemLibrary....(作为系统库像JDK一样)

－－>AddJars－－>导入与Tomcat冲突jar－－>选中jsp-jarOK

解决方法2：修改配置

打开项目目录，编辑.classpath文件

将：<classpathentrykind="lib"path="/............/jsp-jar"/>

改：<classpathentrykind="con"path="/............/jsp-jar"/>

刷新项目OK

结果导入的jar包显示为系统库：