日期:2014-05-19  浏览次数:20826 次

求帮助JSF问题:org.apache.jasper.JasperException: java.lang.NullPointerException
我现在在学习JSF,我试着做了一个HelloWorld,最简单的那种
运行出错
如下:
type Exception report

message 

description The server encountered an internal error () that prevented it from fulfilling this request.

exception 

org.apache.jasper.JasperException: java.lang.NullPointerException
 org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:522)
 org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:356)
 org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:337)
 org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
 javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
 com.sun.faces.context.ExternalContextImpl.dispatch(ExternalContextImpl.java:322)
 com.sun.faces.application.ViewHandlerImpl.renderView(ViewHandlerImpl.java:142)
 com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:87)
 com.sun.faces.lifecycle.LifecycleImpl.phase(LifecycleImpl.java:200)
 com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:117)
 javax.faces.webapp.FacesServlet.service(FacesServlet.java:198)


root cause 

java.lang.NullPointerException
 org.apache.jsp.pages.index_jsp._jspInit(index_jsp.java:31)
 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:337)
 org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
 javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
 com.sun.faces.context.ExternalContextImpl.dispatch(ExternalContextImpl.java:322)
 com.sun.faces.application.ViewHandlerImpl.renderView(ViewHandlerImpl.java:142)
 com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:87)
 com.sun.faces.lifecycle.LifecycleImpl.phase(LifecycleImpl.java:200)
 com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:117)
 javax.faces.webapp.FacesServlet.service(FacesServlet.java:198) 
问题补充:这是我的index页面
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>第一个JSP</title>
</head>
<body>
<f:view>
<h:form>
<h3>请输入名字:</h3>
名称:<h:inputText value="#{user.name}"></h:inputText>
<h:commandButton value="确定" action="login"></h:commandButton>
 </h:form>
</f:view>
</body>
</html>
这是我的faces-config配置文件:
<faces-config>
  <navigation-rule>
  <from-view-id>/pages/index.jsp</from-view-id>
  <navigation-case>
  <from-outcome>login</from-outcome>
  <to-view-id>/pages/welcome.jsp</to-view-id>