小第初次接触jsp,这个错误是怎么回事.说缺少类定义
java.lang.NoClassDefFoundError
java.lang.Class.forName0(Native Method)
java.lang.Class.forName(Class.java:141)
java.awt.GraphicsEnvironment.getLocalGraphicsEnvironment(GraphicsEnvironment.java:62)
java.awt.image.BufferedImage.createGraphics(BufferedImage.java:1041)
java.awt.image.BufferedImage.getGraphics(BufferedImage.java:1031)
org.apache.jsp.randomDigit_jsp._jspService(randomDigit_jsp.java:68)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:133)
javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:311)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:301)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:248)
javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
代码:
<%@ page contentType= "image/jpeg " import= "java.awt.*,java.awt.image.*,java.util.*,javax.imageio.* " %>
<%!
Color getRandColor(int fc,int bc){//给定范围获得随机颜色
Random random = new Random();
if(fc> 255) fc=255;
if(bc> 255) bc=255;
int r=fc+random.nextInt(bc-fc);
int g=fc+random.nextInt(bc-fc);
int b=fc+random.nextInt(bc-fc);
return new Color(r,g,b);
}
%>
<%
//设置页面不缓存
response.setHeader( "Pragma ", "No-cache ");
response.setHeader( "Cache-Control ", "no-cache ");
response.setDateHeader( "Expires ", 0);
// 在内存中创建图象
int width=60, height=20;
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
// 获取图形上下文
Graphics g = image.getGraphics();
//生成随机类
Random random = new Random();
// 设定背景色
g.setColor(getRandColor(200,250));
g.fillRect(0, 0, width, height);
//设定字体
g.setFont(new Font( "Times New Roman ",Font.PLAIN,18));
//画边框
//g.setColor(new Color());
//g.drawRect(0,0,width-1,height-1);
// 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到
g.setColor(getRandColor(160,200));
for (int i=0;i <155;i++)
{
int x = random.nextInt(width);
int y = random.nextInt(height);
int xl = random.nextInt(12);
int yl = random.nextInt(12);
g.drawLine(x,y,x+xl,y+yl);
}
// 取随机产生的认证码(4位数字)
String sRand= " ";
for (int i=0;i <4;i++){
String rand=String.valueOf(random.nextInt(10));
sRand+=rand;
// 将认证码显示到图象中
g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));//调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
g.drawString(rand,13*i+6,16);
}
// 将认证码存入SESSION
session.setAttribute( "rand ",sRand);
// 图象生效
g.dispose();
// 输出图象到页面
ImageIO.write(image, "JPEG ", response.getOutputStream());
%>
那到底还需要什么类呢
[解决办法]
你这是生成验证码图片的代码，我正在用一模一样的，代码错误的可能性不大！
还是看看你调用这个文件的代码吧
[解决办法]
randomDigit_jsp.java打开这个文件，看看68行是什么东东，就知道了
