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电梯直达

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发表于 2006-04-02 20:33 |只看该作者 |倒序浏览

两个文件:GuessBean.java和guess.jsp

GuessBean.java源码:

package test;
import java.util.*;

public class GuessBean
{
int answer;
boolean success;
String hint;
int numGuesses;
public GuessBean()
{
   reset();
}
  public void setGuess(String guess)
  {
   numGuesses++;
   int g;
   try
   {
   g=Integer.parseInt(guess);
   }
   catch(NumberFormatException e)
   {
      g=-1;
   }
  if(g==answer)
  {
success=true;
  }
else if(g==-1)
{
   hint="a number next time";
}
else if(g<answer)
{
   hint="highter";
}
else if(g>answer)
{
   hint="lower";
}
  }
  public boolean getSuccess()
  {
return success;
  }
public String getHint()
{
  return ""+hint;
}
public int getNumGuesses()
{
return numGuesses;
}

public void reset()
{
answer=Math.abs(new Random().nextInt()%100)+1;
success=false;
numGuesses=0;
}
}

--------------------------------------------------------------------------------

guess.jsp源码:

<html>
<head>
<title>猜数字游戏</title>
</head>
<%@ page contentType="text/html;charset=gb2312" %>
<jsp:useBean id="numguess" class="test.GuessBean" scope="session"/>
<jsp:setProperty name="numguess" property="*"/>
<body bgcolor="white">
<h3>
<%
if(numguess.getSuccess())
{ %>
恭喜，你猜中了！
你一共猜了<%=numguess.getNumGuesses() %>次。<p>
<% numguess.reset(); %>
还想<a href="guess.jsp">继续猜</a>?
<%
} else if(numguess.getNumGuesses()==0)
{ %>
<h2>
欢迎来参加猜数字游戏。
</h2><p>
我想出了一个1到100之间的数字。<p>
<form method=get>
你猜是多少?
<input type=text name=guess>
<input type=submit value="Submit">
</form>
<%
} else
{ %>
很好，可惜没对。试试<b><%=numguess.getHint()%></b>
你已经猜了<%=numguess.getNumGuesses() %>次.
<p>我想出了一个1到100之间的数字..
<p>
<form method=get>
输入你猜的数?
<input type=text name=guess>
<input type=submit value="Submit">
</form>
<% }%>
</h3>
</body>
</html>

两个文件都放到d:\Program Files\Apache Software Foundation\Tomcat 5.5\webapps\ROOT
java程序编译后，class文件生成到test文件夹里面
在Tomcat环境下运行

但是浏览guess.jsp文件的时候总是报错~~~但是小弟找不出原因，请高人指点

网页反馈信息：

HTTP Status 500 -

--------------------------------------------------------------------------------

type Exception report

message

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

exception

org.apache.jasper.JasperException: /guess.jsp(6,0) The value for the useBean class attribute test.GuessBean is invalid.
  org.apache.jasper.compiler.DefaultErrorHandler.jspError(DefaultErrorHandler.java:39)
  org.apache.jasper.compiler.ErrorDispatcher.dispatch(ErrorDispatcher.java:405)
  org.apache.jasper.compiler.ErrorDispatcher.jspError(ErrorDispatcher.java:146)
  org.apache.jasper.compiler.Generator$GenerateVisitor.visit(Generator.java:1223)
  org.apache.jasper.compiler.Node$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:3284)
  org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:189)
  org.apache.jasper.compiler.Compiler.compile(Compiler.java:286)
  org.apache.jasper.compiler.Compiler.compile(Compiler.java:267)
  org.apache.jasper.compiler.Compiler.compile(Compiler.java:255)
  org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:556)
  org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:293)
  org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
  org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
  javax.servlet.http.HttpServlet.service(HttpServlet.java:802)

note The full stack trace of the root cause is available in the Apache Tomcat/5.5.11 logs.