一个最简单的jsp不能被tomcat编译

Question

系统环境：
Server version: Apache Tomcat/5.5.9
Server built: Mar 26 2005 02:21:04
Server number: 5.5.9.0
OS Name: Linux
OS Version: 2.6.9-22.ELsmp
Architecture: i386
JVM Version: 1.5.0_05-b05
JVM Vendor: Sun Microsystems Inc.

jsp页面内容

[code="java"]<%@ page contentType="text/html; charset=gb2312" %>
<%@ page import="java.util.*"%>
<%@ page import="java.sql.*"%>
<%= hello %>[/code]

错误提示：
exception

org.apache.jasper.JasperException: Unable to compile class for JSP

An error occurred at line: 4 in the jsp file: /test3.jsp
Generated servlet error:
hello cannot be resolved

org.apache.jasper.compiler.DefaultErrorHandler.javacError(DefaultErrorHandler.java:84)
org.apache.jasper.compiler.ErrorDispatcher.javacError(ErrorDispatcher.java:328)
org.apache.jasper.compiler.JDTCompiler.generateClass(JDTCompiler.java:397)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:288)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:267)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:255)
org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:556)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:293)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:291)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)

Answer 1

[code="java"]
<%= hello %>
[/code]
hello这个变量你没有定义:

[code="java"]
<%
String hello="Hi, world";
%>
<%=hello%>
[/code]