我在MyEclipse->file->new->Web Project 然后取项目名Test,选择的是J2EE1.4创建完成。然后在我创建的项目Test下的WebRoot下新建下Random文件夹，然后在里面新建Random.jsp文件。该文件（Test/WebRoot/Random/Random.jsp）代码如下：
<%@ page language="java" contentType="image/jpeg"; charset="GB2312" pageEncoding="GB2312"%>
<%@ page contentType="image/jpeg" %>
<%@ page import="java.awt.*,java.awt.image.*" %>
<%@ page import="java.util.*,javax.imageio.*" %>
<%@ page import="java.util.Random" %>
<!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="image/jpeg"; charset="GB2312">
<title>Insert title here</title>
</head>
<body>
<%!
//产生随机颜色函数getRandColor
Color getRandColor(int fc,int bc){
Random r=new Random();
if(fc>255) fc=255;
if(bc>255) bc=255;
int red=fc+r.nextInt(bc-fc);//红
int green=fc+r.nextInt(bc-fc);//绿
int blue=fc+r.nextInt(bc-fc);//蓝
return new Color(red,green,blue);
}
%>
<%
//设置页面不缓存
response.setHeader("Pragma","No-cache");
response.setHeader("Cache-Control","no-cache");
response.setDateHeader("Expires",0);
//创建随机类
Random r=new Random();
//在内存中创建图象，宽度为width,高度为height
int width=60,height=20;
BufferedImage pic=new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
//获取图形上下文环境
Graphics gc=pic.getGraphics();
//设定背景色并进行填充
gc.setColor(getRandColor(200,250));
gc.fillRect(0,0,width,height);
//设定图形上下文环境字体
gc.setFont(new Font("Times New Roman",Font.PLAIN,18));
//随机产生200条干扰直线，使图象中的认证码不易被其他分析程序探测到
gc.setColor(getRandColor(160,200));
for(int i=0;i<200;i++)
{
int x1=r.nextInt(width);
int y1=r.nextInt(height);
int x2=r.nextInt(15);
int y2=r.nextInt(15);
gc.drawLine(x1,y1,x1+x2,y1+y2);
}
//随机产生100个干扰点，使图象中的认证码不易被其他分析程序探测到
gc.setColor(getRandColor(120,240));
for(int i=0;i<100;i++)
{
int x=r.nextInt(width);
int y=r.nextInt(height);
gc.drawOval(x,y,0,0);
}
//随机产生4位数字的验证码
String RS="";
String rn="";
for(int i=0;i<4;i++){
//产生10以内随机数字rn
rn=String.valueOf(r.nextInt(10));
RS+=rn;
//将认证码用drawString函数显示到图象里
gc.setColor(new Color(20+r.nextInt(110),20+r.nextInt(110),20+r.nextInt(110)));
gc.drawString(rn,13*i+6,16);
}
//释放图形上下文环境
gc.dispose();
//将认证码RS存入SESSION中共享
session.setAttribute("random",RS);
//输出生成后的验证码图象到页面
ImageIO.write(pic,"JPEG",response.getOutputStream());
%>
</body>
</html>
运行该页面出现错误如下：
exception
org.apache.jasper.JasperException: org.apache.jasper.JasperException: Unable to load class for JSP
org.apache.jasper.servlet.JspServletWrapper.getServlet(JspServletWrapper.java:156)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:329)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
root cause
org.apache.jasper.JasperException: Unable to load class for JSP
org.apache.jasper.JspCompilationContext.load(JspCompilationContext.java:600)
org.apache.jasper.servlet.JspServletWrapper.getServlet(JspServletWrapper.java:144)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:329)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
哪位高手指点下，是什么原因，先谢了。
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