1 import java.awt.Color;
  2 import java.awt.Font;
  3 import java.awt.Graphics;
  4 import java.awt.image.BufferedImage;
  5 import java.util.Random;
  6 import javax.imageio.ImageIO;
  7 import javax.servlet.http.HttpServletRequest;
  8 import javax.servlet.http.HttpServletResponse;
  9 import javax.servlet.http.HttpSession;
 10 
 11 /**
 12  * 验证码图片生成工具
 13  *  使用JAVA生成的图片验证码，调用getRandcode方法获取图片验证码，以流的方式传输到前端页面。
 14  *  
 15  * 
 16  * 作者: zhoubang 
 17  * 日期：2015年8月7日 上午10:41:05
 18  */
 19 public class Captcha {
 20 
 21     public static final String RANDOMCODEKEY = "sess_captcha";// 放到session中的key
 22     private Random random = new Random();
 23     private String randString = "0123456789";// 随机产生的字符串
 24 
 25     private int width = 80;// 图片宽
 26     private int height = 26;// 图片高
 27     private int lineSize = 40;// 干扰线数量
 28     private int stringNum = 4;// 随机产生字符数量
 29 
 30     /*
 31      * 获得字体
 32      */
 33     private Font getFont() {
 34         return new Font("Fixedsys", Font.CENTER_BASELINE, 18);
 35     }
 36 
 37     /*
 38      * 获得颜色
 39      */
 40     private Color getRandColor(int fc, int bc) {
 41         if (fc > 255)
 42             fc = 255;
 43         if (bc > 255)
 44             bc = 255;
 45         int r = fc + random.nextInt(bc - fc - 16);
 46         int g = fc + random.nextInt(bc - fc - 14);
 47         int b = fc + random.nextInt(bc - fc - 18);
 48         return new Color(r, g, b);
 49     }
 50 
 51     /*
 52      * 绘制字符串
 53      */
 54     private String drowString(Graphics g, String randomString, int i) {
 55         g.setFont(getFont());
 56         g.setColor(new Color(random.nextInt(101), random.nextInt(111), random.nextInt(121)));
 57         String rand = String.valueOf(getRandomString(random.nextInt(randString.length())));
 58         randomString += rand;
 59         g.translate(random.nextInt(3), random.nextInt(3));
 60         g.drawString(rand, 13 * i, 16);
 61         return randomString;
 62     }
 63 
 64     /*
 65      * 绘制干扰线
 66      */
 67     private void drowLine(Graphics g) {
 68         int x = random.nextInt(width);
 69         int y = random.nextInt(height);
 70         int xl = random.nextInt(13);
 71         int yl = random.nextInt(15);
 72         g.drawLine(x, y, x + xl, y + yl);
 73     }
 74 
 75     /*
 76      * 获取随机的字符
 77      */
 78     public String getRandomString(int num) {
 79         return String.valueOf(randString.charAt(num));
 80     }
 81     
 82     
 83     /**
 84      * 生成随机图片
 85      */
 86     public void getRandcode(HttpServletRequest request, HttpServletResponse response) {
 87         HttpSession session = request.getSession();
 88         // BufferedImage类是具有缓冲区的Image类,Image类是用于描述图像信息的类
 89         BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_BGR);
 90         Graphics g = image.getGraphics();// 产生Image对象的Graphics对象,改对象可以在图像上进行各种绘制操作
 91         g.fillRect(0, 0, width, height);
 92         g.setFont(new Font("Times New Roman", Font.ROMAN_BASELINE, 18));
 93         g.setColor(getRandColor(110, 133));
 94         // 绘制干扰线
 95         for (int i = 0; i <= lineSize; i++) {
 96             drowLine(g);
 97         }
 98         // 绘制随机字符
 99         String randomString = "";
100         for (int i = 1; i <= stringNum; i++) {
101             randomString = drowString(g, randomString, i);
102         }
103         session.removeAttribute(RANDOMCODEKEY);
104         session.setAttribute(RANDOMCODEKEY, randomString);
105         g.dispose();
106         try {
107             ImageIO.write(image, "JPEG", response.getOutputStream());// 将内存中的图片通过流动形式输出到客户端
108         } catch (Exception e) {
109             e.printStackTrace();
110         }
111     }
112 }

 1 import java.io.IOException;
 2 import javax.servlet.ServletException;
 3 import javax.servlet.annotation.WebServlet;
 4 import javax.servlet.http.HttpServlet;
 5 import javax.servlet.http.HttpServletRequest;
 6 import javax.servlet.http.HttpServletResponse;
 7 
 8 @WebServlet(description = "图片验证码生成", urlPatterns = { "/ImageServlet" })
 9 public class ImageServlet extends HttpServlet {
10     private static final long serialVersionUID = 1L;
11 
12     public ImageServlet() {
13         super();
14     }
15 
16     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
17         response.setContentType("image/jpeg");// 设置相应类型,告诉浏览器输出的内容为图片
18         response.setHeader("Pragma", "No-cache");// 设置响应头信息，告诉浏览器不要缓存此内容
19         response.setHeader("Cache-Control", "no-cache");
20         response.setDateHeader("Expire", 0);
21         Captcha randomValidateCode = new Captcha();
22         try {
23             randomValidateCode.getRandcode(request, response);// 输出图片方法
24         } catch (Exception e) {
25             e.printStackTrace();
26         }
27     }
28 
29     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
30         doGet(request, response);
31     }
32 }