输出随机验证码图片

 1 /**
 2  * //输出随机验证码图片：CAPTCHA图像
 3  */
 4 public class ServletDemo1 extends HttpServlet {
 5     private static final long serialVersionUID = 1L;
 6 
 7     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
 8       //图片的宽度
 9         int width=120;
10         //图片的高度
11         int height=25;
12         //生成一张内存图片
13         BufferedImage  image=new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
14         //开始画图片
15         //获取画笔
16         Graphics g=image.getGraphics();
17         //先画边框
18         g.setColor(Color.BLUE);
19         g.drawRect(0, 0, width, height);
20         //填充背景
21         g.setColor(Color.YELLOW);
22         g.fillRect(1, 1, width-2, height-2);
23         //开始画斜线
24         g.setColor(Color.BLACK);
25         Random  r=new Random();
26         for (int i = 0; i < 9; i++) {
27             g.drawLine(r.nextInt(width), r.nextInt(height),r.nextInt(width), r.nextInt(height));
28         }
29         //开始画数字验证码
30         g.setColor(Color.RED);
31         g.setFont(new Font("宋体", Font.ITALIC, 19));
32         //验证码的初始横坐标
33         String base = "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";
34         int x = 20;
35 //        for (int i = 0; i < 4; i++) {
36 //            g.drawString(r.nextInt(10)+"", x, 20);
37 //            x+=18;
38 //        }
39         //中文验证码
40         for (int i = 0; i < 4; i++) {
41             g.drawString(base.charAt(r.nextInt(base.length()))+"", x, 20);
42             
43             x+=18;
44         }
45         
46         //去掉缓存
47         response.setHeader("Expires", "-1");
48         response.setHeader("Cache-Control", "no-cache");
49         response.setHeader("Pragma", "no-cache");
50         //输出图片
51         ImageIO.write(image, "jpg", response.getOutputStream());
52         
53     }
54 
55     /**
56      * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
57      *      response)
58      */
59     protected void doPost(HttpServletRequest request, HttpServletResponse response)
60             throws ServletException, IOException {
61         doGet(request, response);
62     }
63 
64 }

验证码的jsp页面

 1 <%@ page language="java" contentType="text/html; charset=utf-8"
 2     pageEncoding="utf-8"%>
 3 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
 4 <html>
 5 <head>
 6 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
 7 <title>Insert title here</title>
 8 </head>
 9 <body>
10 <form action="" method="post">
11 用户名:<input type="text" />
12 密码:<input type="password" />
13 <input type="submit" value="提交"><img id="yanzhengma" src="/day08_Response_Request/servlet/ServletDemo1" onclick="change()">
14 <a href="javascript:change()">看不清</a>
15 </form>
16 <script>
17   function change(){
18       var imgObj=document.getElementById("yanzhengma");
19       imgObj.src="/day08_Response_Request/servlet/ServletDemo1?time"+new Date();//因为浏览器会判断请求地址是不是改变，如果没变，就不会提交申请
20   }
21 </script>
22 </body>
23 </html>