Unable to load class for JSP（在线等高手）

qiaobinloverabbi 2011-09-06 04:42:52

小弟刚自学jsp，写了个很简单的bean，可是在jsp文件中加载的时候出错
错误信息如下
org.apache.jasper.JasperException: /WebRoot/1.jsp(11,1) The value for the useBean class attribute bean.unit4.Circle is invalid.
org.apache.jasper.compiler.DefaultErrorHandler.jspError(DefaultErrorHandler.java:40)
org.apache.jasper.compiler.ErrorDispatcher.dispatch(ErrorDispatcher.java:407)
org.apache.jasper.compiler.ErrorDispatcher.jspError(ErrorDispatcher.java:148)
org.apache.jasper.compiler.Generator$GenerateVisitor.visit(Generator.java:1233)
org.apache.jasper.compiler.Node$UseBean.accept(Node.java:1178)
org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2361)
org.apache.jasper.compiler.Node$Visitor.visitBody(Node.java:2411)
org.apache.jasper.compiler.Node$Visitor.visit(Node.java:2417)
org.apache.jasper.compiler.Node$Root.accept(Node.java:495)
org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2361)
org.apache.jasper.compiler.Generator.generate(Generator.java:3459)
org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:231)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:354)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:334)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:321)
org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:592)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:328)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)

把页面刷新几次后就变成了

org.apache.jasper.JasperException: org.apache.jasper.JasperException: Unable to load class for JSP
org.apache.jasper.servlet.JspServletWrapper.getServlet(JspServletWrapper.java:161)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:340)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)

root cause

org.apache.jasper.JasperException: Unable to load class for JSP
org.apache.jasper.JspCompilationContext.load(JspCompilationContext.java:630)
org.apache.jasper.servlet.JspServletWrapper.getServlet(JspServletWrapper.java:149)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:340)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)

root cause

java.lang.ClassNotFoundException: org.apache.jsp.WebRoot._1_jsp
java.net.URLClassLoader$1.run(Unknown Source)
java.security.AccessController.doPrivileged(Native Method)
java.net.URLClassLoader.findClass(Unknown Source)
org.apache.jasper.servlet.JasperLoader.loadClass(JasperLoader.java:134)
org.apache.jasper.servlet.JasperLoader.loadClass(JasperLoader.java:66)
org.apache.jasper.JspCompilationContext.load(JspCompilationContext.java:628)
org.apache.jasper.servlet.JspServletWrapper.getServlet(JspServletWrapper.java:149)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:340)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)

不知道是什么原因，myeclipse是9.0的，自动编译，.class也是和bena同结构的目录中，放在WEB-INF/classes里面
请高手告诉一下，tomcat是6.0

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qiaobinloverabbi 2011-09-06

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[Quote=引用 5 楼 everwhl 的回复:]

class = "bean.unit4.Circle" 是不是路径写的有问题还有circle最好和bean的名字不要一样换个别的名字试试
[/Quote]

myeclipse默认的.class输出目录是在web-inf/classes里面
这个class的路径就是web-inf/classes/bean/unit4/Circle 应该没错

EverWHL 2011-09-06

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class = "bean.unit4.Circle" 是不是路径写的有问题还有circle最好和bean的名字不要一样换个别的名字试试

qiaobinloverabbi 2011-09-06

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这个都对应了也不行 tomcat重启也不行 - -

qiaobinloverabbi 2011-09-06

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[Quote=引用 1 楼 swift123 的回复:]

出错提示：/WebRoot/1.jsp(11,1) The value for the useBean class attribute bean.unit4.Circle is invalid.
检查下你的1.jsp
类Circle中有没有userBean的属性？
[/Quote]

<%@ page language="java" contentType="text/html; charset=gb2312"
pageEncoding="gb2312"%>
<%@ page import = "bean.unit4.*" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>Insert title here</title>
</head>
<body>
<jsp:useBean id="circle" class = "bean.unit4.Circle" scope = "page"></jsp:useBean>
<% circle.setRadius(100);

EverWHL 2011-09-06