我将bean对象从servlet传递给jsp文件,并希望使用bean值,如下所示,但它会引发运行时错误 . 我究竟做错了什么?
<%@ page import = "beans.UserInfo" %>
<%
UserInfo userInfo = (UserInfo)session.getAttribute("userInfo");
String userName = userInfo.getUserName();
%>
执行如下:
例外
org.apache.jasper.JasperException:java.lang.NullPointerException org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:491)org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:419)org .apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)javax.servlet.http.HttpServlet.service(httpServlet.java:717 )
根本原因
java.lang.NullPointerException org.apache.jsp.Login_jsp._jspService(Login_jsp.java:60)org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)javax.servlet.http.HttpServlet.service(HttpServlet .java:717)org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:377)org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)org.apache.jasper.servlet.JspServlet .service(JspServlet.java:260)javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
note备注根本原因的完整堆栈跟踪在Apache Tomcat /6.0.28日志中 .
1 回答
您在
doPost
或doGet
中的代码应该如下所示,您正在构建beans.UserInfo
并发出Dispatcher
的forward
方法 .