Jsp页面实现验证码

 1 <%@ page language="java" contentType="text/html; charset=UTF-8"
 2     pageEncoding="UTF-8"%>
 3 <%@ page import="java.util.Random"%>
 4 <%@ page import="java.io.OutputStream"%>
 5 <%@ page import="java.awt.Color"%>
 6 <%@ page import="java.awt.Font"%>
 7 <%@ page import="java.awt.Graphics"%>
 8 <%@ page import="java.awt.image.BufferedImage"%>
 9 <%@ page import="javax.imageio.ImageIO"%>
10 <%
11     int width = 60;
12     int height = 32;
13     //create the image
14     BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
15     Graphics g = image.getGraphics();
16     // set the background color
17     g.setColor(new Color(0xDCDCDC));
18     g.fillRect(0, 0, width, height);
19     // draw the border
20     g.setColor(Color.black);
21     g.drawRect(0, 0, width - 1, height - 1);
22     // create a random instance to generate the codes
23     Random rdm = new Random();
24     String hash1 = Integer.toHexString(rdm.nextInt());
25     System.out.print(hash1);
26     // make some confusion
27     for (int i = 0; i < 50; i++) {
28         int x = rdm.nextInt(width);
29         int y = rdm.nextInt(height);
30         g.drawOval(x, y, 0, 0);
31     }
32     // generate a random code
33     String capstr = hash1.substring(0, 4);
34     //将生成的验证码存入session
35     session.setAttribute("validateCode", capstr);
36     g.setColor(new Color(0, 100, 0));
37     g.setFont(new Font("Candara", Font.BOLD, 24));
38     g.drawString(capstr, 8, 24);
39     g.dispose();
40     //输出图片
41     response.setContentType("image/jpeg");
42     out.clear();
43     out = pageContext.pushBody();
44     OutputStream strm = response.getOutputStream();
45     ImageIO.write(image, "jpeg", strm);
46     strm.close();
47 %>
原文地址:https://www.cnblogs.com/mlsq2015/p/5553032.html