初学者一个简单的javaBean问题(送分问题)
我是刚学jsp,以前用过php,asp等。但在用javaBean时发现一些小问题,请各位朋友帮忙下。
类的代码如下:
package bean;
public class sampleBean
{
private String sample = "Start value";
public String getSample() {
return sample;
}
public void setSample(String newValue) {
if(newValue != null) {
sample = newValue;
}
}
}
我将它生成sampleBean.class, 并放在Tomcat 5.0/webapps/ROOT/WEB-INF/classes 里面,并已经重启。
用sample.jsp 调用这个类。
<%@ page contentType="text/html;charset=GBK"%>
<html>
<head>
<title>Servlet使用JSP</title>
</head>
<jsp:useBean id="myBean"
scope="application" class="bean.sampleBean"/>
<body bgcolor="gray">
<h2>JSP使用JavaBean的例子:</h2>
<hr>
调用jsp:setProperty之前的值:
<jsp:getProperty name="myBean" property="sample"/>
<p>
<jsp:setProperty name="myBean"
property="sample" value="hhhhhhhhhhhhh"/>
调用jsp:setProperty之后的值:
<jsp:getProperty name="myBean1" property="sample"/>
</body>
</html>
但调试时没有通过,出现以下错误。
type Exception report
message
description The server encountered an internal error () that prevented it from fulfilling this request.
exception
org.apache.jasper.JasperException: /sample1.jsp(6,1) The value for the useBean class attribute bean.sampleBean 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.
请问是何原因,谢谢!