使用JavaBean报错啦！（见问题补充）

bean_test.jsp文件如下：
<jsp:useBean id="test" class="BeanTest"/>
<%
out.println(test.sayHello());
%>

BeanTest.java文件如下：
public class BeanTest
{
String message="Hello,world!";
public void BeanTest(){}
public String sayHello()
{
return message;
}
}

浏览器报错信息如下：
exception

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

An error occurred at line: 0 in the jsp file: /bean_test.jsp

Generated servlet error:
[javac] Compiling 1 source file

C:\Program Files\Apache Group\Tomcat 4.1\work\Standalone\localhost\jsp\bean_test_jsp.java:41: cannot resolve symbol
symbol : class BeanTest
location: class org.apache.jsp.bean_test_jsp
BeanTest test = null;
^

An error occurred at line: 0 in the jsp file: /bean_test.jsp