input.jsp
<%@ page contentType="text/html; charset=gb2312" language="java" import="java.sql.*" errorPage="" %>
<!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>无标题文档</title>
</head><body><table width="560" border="0" cellpadding="0" cellspacing="0">
  <!--DWLayoutTable-->
  <form name="form1" method="post" action="input2.jsp">
  <tr>
    <td height="42" colspan="2" valign="top">测试:</td>
  </tr>
  <tr>
    <td width="121" height="26" align="right" valign="top">性别:</td>
    <td width="439" valign="top">
      <input type="radio" name="gender" value="male">
      男
      <input type="radio" name="gender" value="female">
      女
    </td>
  </tr>
  <tr>
    <td height="24" align="right" valign="top">年龄:</td>
    <td valign="top"><input type="text" name="age"></td>
  </tr>
  <tr>
    <td height="24" align="right" valign="top">体重:</td>
    <td valign="top"><input type="text" name="weight"></td>
  </tr>
  <tr>
    <td height="27" valign="top"><input type="submit" name="Submit" value="提交"></td>
    <td valign="top"><!--DWLayoutEmptyCell-->&nbsp;</td>
  </tr>
  <tr>
    <td height="158">&nbsp;</td>
    <td>&nbsp;</td>
  </tr></form>
</table>
</body>
</html>input2.jsp
<%@ page contentType="text/html; charset=gb2312" language="java" import="java.sql.*" errorPage="" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<jsp:useBean id = "Calculator" class ="CalMeasure" scope="session" />
<jsp:setProperty name ="Calculator" property="*" />
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>无标题文档</title>
</head><body>
你的结果:<jsp:getProperty name="Calculator" property="result" />
</body>
</html>CalMeasure.classimport java.io.*;
public class CalMeasure {       int weight;
       int age;
       int result =0;//1
       String gender;       public CalMeasure(){
       
       }
       public int getWeight(){
          return this.weight;
       }
       public int getAge(){
          return this.age;
       }
       public String getGender(){
          return this.gender;
       }
       public int getResult(){
          return calculate();//
       }       public void setWeight(int weight_){
           this.weight = weight_;
       }
       public void setAge(int age_){
          this.age = age_;
       }
       public void setGender(String gender_){
           this.gender = gender_;
       }
       private int calculate(){
            if(this.result!=0){
                return this.result;
             }else{
         float fltTEN = (float)(weight * 2); //2
         this.result = (int)fltTEN;//2;
         return this.result;//////////////
        }//else
        }      public static void main(String[] args) {
       
      CalMeasure p=new CalMeasure(); 
            System.out.println(p.calculate());               
      }}//class出现错误:
type Exception reportmessage description The server encountered an internal error () that prevented it from fulfilling this request.exception org.apache.jasper.JasperException: /input2.jsp(3,0) The value for the useBean class attribute CalMeasure 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.请问是怎么回事啊?????????

解决方案 »

  1.   

    <jsp:useBean id = "Calculator" class ="CalMeasure" scope="session" />记得要带上包名的吧错误提示的是CalMeasure这个东西不存在似的
      

  2.   

    你的javaBean里还有这个: public static void main(String[] args) {
           
          CalMeasure p=new CalMeasure(); 
                System.out.println(p.calculate());               
          }
    呵呵..只有方法.
      

  3.   

    <jsp:useBean id = "Calculator" class ="CalMeasure" scope="session" />
    需要指定包名的否则JAVA不知道那个类的路径是什么也不知道到那里去找
      

  4.   

    你bean里面有main函数.在用<jsp:getProperty ..的时候.是不是要把类new一下.试一下看看.
      

  5.   

    现在<jsp:useBean id = "Calculator" class ="bao.CalMeasure" scope="session" />java文件里也package bao;
    可还是那个错误啊
      

  6.   

    是不是这个 用到了JSP标签?而我没标签库?
      

  7.   

    我的也有类似问题,麻烦顺便看一下我这是什么问题
    <jsp:useBean id="dbConn" class="org.apache.jsp.ereport"  scope="page"/>
    <jsp:useBean id="file"   class="org.apache.jsp.FileUpload"  scope="page"/>
    exception javax.servlet.ServletException: org/apache/jsp/ereport
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:244)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
    root cause java.lang.NoClassDefFoundError: org/apache/jsp/ereport
    java.lang.Class.getDeclaredConstructors0(Native Method)
    java.lang.Class.privateGetDeclaredConstructors(Unknown Source)
    java.lang.Class.getConstructor0(Unknown Source)
    java.lang.Class.newInstance0(Unknown Source)
    java.lang.Class.newInstance(Unknown Source)
    org.apache.jasper.servlet.JspServletWrapper.getServlet(JspServletWrapper.java:137)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:307)
    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