按时打发士大夫

 1 ///创建图像缓冲区
 2         BufferedImage bi = new BufferedImage(68, 22, BufferedImage.TYPE_INT_RGB);
 3         //通过缓冲区创建一个画布
 4         Graphics g = bi.getGraphics();
 5         Color c = new Color(200, 150, 255); //创建颜色
 6         //为画布创建背景颜色
 7         g.setColor(c);
 8         g.fillRect(0, 0, 68, 22); //fillRect:填充指定的矩形
 9         //转化为字符型的数组
10         char[] ch = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789".toCharArray();
11         Random r = new Random();
12         int len = ch.length;
13         int index; //index用于存放随机数字
14         StringBuffer sb = new StringBuffer();
15         for (int i = 0; i < 4; i++) {
16             //产生随机数字
17             index = r.nextInt(len);
18             //设置颜色
19             g.setColor(new Color(r.nextInt(88), r.nextInt(188), r.nextInt(255)));
20             //画数字以及数字的位置
21             g.drawString(ch[index] + "", (i * 15) + 3, 18);
22             sb.append(ch[index]);
23         }
24 
25         request.getSession().setAttribute("piccode", sb.toString());
26         ImageIO.write(bi, "JPG", response.getOutputStream());