请帮忙看一下这是什么问题？？---JSF
我作了一个简单的jsf登录验证的测试工程，启动tomcat并在浏览器输入地址后出现如下提示：

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

例外

org.apache.jasper.JasperException
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:512)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:395)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)

原因

java.lang.NullPointerException
javax.faces.webapp.UIComponentTag.setupResponseWriter(UIComponentTag.java:615)
javax.faces.webapp.UIComponentTag.doStartTag(UIComponentTag.java:217)
org.apache.myfaces.taglib.core.ViewTag.doStartTag(ViewTag.java:71)
org.apache.jsp.index_jsp._jspx_meth_f_view_0(index_jsp.java:92)
org.apache.jsp.index_jsp._jspService(index_jsp.java:66)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:334)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)


------解决方案--------------------
请说明一下原因，呵呵学习一下啊！
------解决方案--------------------
我还以为结尾是.faces呢！
我的异常网推荐解决方案：The server encountered an internal error () that prevented it from fulfilling this request.,http://www.aiyiweb.com/java-web/317.html