我是刚开始学JSP的，在网站上下载了好几个JSP源码，放到我的webapps/ROOT/lyb（自己新建的文件夹）下，但都不能用呀！到底还要如何配置？我的系统配置是：WIN2K+j2sdk1.4.1_07+Tomcat 5.0

出现的错误信息是：

HTTP Status 500 -

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type Exception report

message

description The server encountered an internal error () that prevented it from fulfilling this request.

exception

org.apache.jasper.JasperException: /lyb/index.jsp(3,0) The value for the useBean class attribute com.guestbook.DBConnection is invalid.
    org.apache.jasper.compiler.DefaultErrorHandler.jspError(DefaultErrorHandler.java:39)
    org.apache.jasper.compiler.ErrorDispatcher.dispatch(ErrorDispatcher.java:409)
    org.apache.jasper.compiler.ErrorDispatcher.jspError(ErrorDispatcher.java:150)
    org.apache.jasper.compiler.Generator$GenerateVisitor.visit(Generator.java:1227)
    org.apache.jasper.compiler.Node$UseBean.accept(Node.java:1116)
    org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2163)
    org.apache.jasper.compiler.Node$Visitor.visitBody(Node.java:2213)
    org.apache.jasper.compiler.Node$Visitor.visit(Node.java:2219)
    org.apache.jasper.compiler.Node$Root.accept(Node.java:456)
    org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2163)
    org.apache.jasper.compiler.Generator.generate(Generator.java:3272)
    org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:244)
    org.apache.jasper.compiler.Compiler.compile(Compiler.java:470)
    org.apache.jasper.compiler.Compiler.compile(Compiler.java:451)
    org.apache.jasper.compiler.Compiler.compile(Compiler.java:439)
    org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:511)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:295)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:802)



note The full stack trace of the root cause is available in the Apache Tomcat/5.0.28 logs.


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Apache Tomcat/5.0.28