如何用jsp页面生成随机的验证数字码
checkNum.jsp

<%@ page language="java" import="java.util.*,java.sql.*" pageEncoding="UTF-8"%><%@ page contentType="image/jpeg" import="java.awt.*,java.awt.image.*,javax.imageio.*"%>
<%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%>
<%!Color getRandColor(int fc,int bc)//给定范围随机选颜色{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);}%><%response.setHeader("Pragma","No-cache");//设置页面不缓冲response.setHeader("Cache-Control","no-cache");response.setDateHeader("Expires",0);int width=60,height=20;BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);Graphics g = image.getGraphics();//获取图像上下文Random random = new Random();//生成随机对象g.setColor(getRandColor(200,250));g.fillRect(0,0,width,height);g.setFont(new Font("Times New Roman",Font.PLAIN,18));//设置字体for(int i=0;i<155;i++){int x=random.nextInt(width);int y=random.nextInt(height);int x1 = random.nextInt(12);int y1 = random.nextInt(12);g.drawLine(x,y,x+x1,y+y1);}//随机产生验证码String sRand = "";for(int i=0;i<4;i++){String rand = String.valueOf(random.nextInt(10));sRand+=rand;//将验证码显示到图像中g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));//设置显示随机数的颜色g.drawString(rand,13*i+6,16);}//将验证码存放到session中session.setAttribute("rand",sRand);//图像生效g.dispose();//输出图像到页面ImageIO.write(image,"JPEG",response.getOutputStream());out.clear();out = pageContext.pushBody();
%>
可以在登录login.jsp下直接通过： 这种格式调用； 验证码:<input class="imgbutton" name="checknum" type="text" size="15" id ="checknum" maxlength="4"/> <img src="checknum.jsp" alt="Change" border="1" onclick="changeCheckNum()"/><br/> <input type="submit" name="submit" value="login"/>

1楼listensolo刚刚

转走了，这几天刚好在用