JSP动态生成验证码存储在session作用范围内_JSP编程_

<%@ page import="java.awt.*,java.awt.image.*,java.util.*,com.sun.image.codec.jpeg.*" %><%! //根据提供的ab产生随机的颜色变化范围 Color getColor(int a,int b){ int n=b-a; Random rd=new Random(); int cr=a+rd.nextInt(n); int cg=a+rd.nextInt(n); int cb=a+rd.nextInt(n); return new Color(cr,cg,cb); } %><% //下边三行取消客户端游览器缓存验证码的功能 response.setHeader("Pragma","No-cache"); response.setHeader("Cache-Control","no-cache"); response.setDateHeader("Expires", 0); int width=60, height=20; //在内存中生成一个图像 BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); Graphics g = image.getGraphics(); Random random = new Random(); g.setColor(getColor(200,250)); g.fillRect(0, 0, width, height); g.setFont(new Font("Times New Roman",Font.BOLD,18)); g.setColor(getColor(160,200)); for (int i=0;i<160;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); } String number=String.valueOf(1000+random.nextInt(8999)); String name=request.getParameter("name"); session.setAttribute(name,number); g.setColor(getColor(20,130)); int x=(int)(width*0.2); int y=(int)(height*0.8); g.drawString(number,x,y); g.dispose(); JPEGImageEncoder encoder=JPEGCodec.createJPEGEncoder(response.getOutputStream()); encoder.encode(image); out.close(); %>

<%@ page contentType="text/html; charset=gb2312" language="java" import="java.sql.*" errorPage="" %><% //同样实现取消客户端缓存 response.setHeader("Pragma","No-cache"); response.setHeader("Cache-Control","no-cache"); response.setDateHeader("Expires", 0); String name="loginCode"; %> 验证码: