1 package com.cgyue;
2
3 import java.awt.Color;
4 import java.awt.Font;
5 import java.awt.Graphics;
6 import java.awt.image.BufferedImage;
7 import java.io.IOException;
8 import java.util.Random;
9
10 import javax.imageio.ImageIO;
11 import javax.servlet.ServletException;
12 import javax.servlet.http.HttpServlet;
13 import javax.servlet.http.HttpServletRequest;
14 import javax.servlet.http.HttpServletResponse;
15
16 /**
17 * 生成图形验证码的Servlet
18 */
19 public class ImageCodeMakerServlet extends HttpServlet {
20
21 public void doGet(HttpServletRequest request, HttpServletResponse response)
22 throws ServletException, IOException {
23 doPost(request, response);
24 }
25
26 /**
27 * @see javax.servlet.http.HttpServlet#void
28 * (javax.servlet.http.HttpServletRequest,
29 * javax.servlet.http.HttpServletResponse)
30 */
31 public void doPost(HttpServletRequest request, HttpServletResponse response)
32 throws ServletException, IOException {
33 // 首先设置页面不缓存
34 response.setHeader("Pragma", "No-cache");
35 response.setHeader("Cache-Control", "no-cache");
36 response.setDateHeader("Expires", 0);
37
38 // 定义图片的宽度和高度
39 int width = 90, height = 40;
40 // 创建一个图像对象
41 BufferedImage image = new BufferedImage(width, height,
42 BufferedImage.TYPE_INT_RGB);
43 // 得到图像的环境对象
44 Graphics g = image.createGraphics();
45
46 Random random = new Random();
47 // 用随机颜色填充图像背景
48 g.setColor(getRandColor(180, 250));
49 g.fillRect(0, 0, width, height);
50 for (int i = 0; i < 5; i++) {
51 g.setColor(getRandColor(50, 100));
52 int x = random.nextInt(width);
53 int y = random.nextInt(height);
54 g.drawOval(x, y, 4, 4);
55 }
56 // 设置字体，下面准备画随机数
57 g.setFont(new Font("", Font.PLAIN, 40));
58 // 随机数字符串
59 String sRand = "";
60 for (int i = 0; i < 4; i++) {
61 // 生成四个数字字符
62 String rand = String.valueOf(random.nextInt(10));
63 sRand += rand;
64 // 生成随机颜色
65 g.setColor(new Color(20 + random.nextInt(80), 20 + random
66 .nextInt(100), 20 + random.nextInt(90)));
67 // 将随机数字画在图像上
68 g.drawString(rand, (17 + random.nextInt(3)) * i + 8, 34);
69
70 // 生成干扰线
71 for (int k = 0; k < 12; k++) {
72 int x = random.nextInt(width);
73 int y = random.nextInt(height);
74 int xl = random.nextInt(9);
75 int yl = random.nextInt(9);
76 g.drawLine(x, y, x + xl, y + yl);
77 }
78 }
79
80 // 将生成的随机数字字符串写入Session
81 request.getSession().setAttribute("randcode", sRand);
82 // 使图像生效
83 g.dispose();
84 // 输出图像到页面
85 ImageIO.write(image, "JPEG", response.getOutputStream());
86 }
87
88 /**
89 * 产生一个随机的颜色
90 * @param fc 颜色分量最小值
91 * @param bc 颜色分量最大值
92 * @return
93 */
94 public Color getRandColor(int fc, int bc) {
95 Random random = new Random();
96 if (fc > 255){
97 fc = 255;
98 }
99 if (bc > 255){
100 bc = 255;
101 }
102 int r = fc + random.nextInt(bc - fc);
103 int g = fc + random.nextInt(bc - fc);
104 int b = fc + random.nextInt(bc - fc);
105 return new Color(r, g, b);
106 }
107 }
