关于javabean找不到的问题

我的.class文件在包\WEB-INF\classes\cn\fang\dashen下
jsp中相关的语句如下：
<%@ page import="cn.fang.dashen.Triangle"%>
<jsp:useBean id="tri" class="cn.fang.dashen.Triangle" scope="page"/>出现异常如下：
org.apache.jasper.JasperException: Cannot find any information on property 'Triangle' in a bean of type 'cn.fang.dashen.Triangle'
org.apache.jasper.runtime.JspRuntimeLibrary.getReadMethod(JspRuntimeLibrary.java:839)
org.apache.jasper.compiler.Generator$GenerateVisitor.visit(Generator.java:1048)
org.apache.jasper.compiler.Node$GetProperty.accept(Node.java:1106)
org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2343)
org.apache.jasper.compiler.Node$Visitor.visitBody(Node.java:2393)
org.apache.jasper.compiler.Node$Visitor.visit(Node.java:2399)
org.apache.jasper.compiler.Node$Root.accept(Node.java:489)
org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2343)
org.apache.jasper.compiler.Generator.generate(Generator.java:3365)
org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:199)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:315)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:295)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:282)
org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:586)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:317)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)