关于jsp javabean的

The server encountered an internal error () that prevented it from fulfilling this request.exception org.apache.jasper.JasperException: Unable to compile class for JSP: An error occurred at line: 4 in the jsp file: /common.jspwebdb cannot be resolved to a type1: <%@ page import="java.util.Properties" %>2: <%@ page errorPage="errorpage.jsp" %>3: 4: <jsp:useBean id="webdb" class="webdb" scope="session"/>5: 6: <%!7: public String convert(String s){