后端验证码文件

  1. package web;
  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.io.OutputStream;
  9. import java.util.Random;
  11. import javax.servlet.ServletException;
  12. import javax.servlet.http.HttpServlet;
  13. import javax.servlet.http.HttpServletRequest;
  14. import javax.servlet.http.HttpServletResponse;
  15. import javax.servlet.http.HttpSession;
  17. public class CheckcodeServlet extends HttpServlet {
  19.      public void service(HttpServletRequest request, HttpServletResponse response)
  20.                throws ServletException, IOException {
  21.           System.out.println("CheckcodeServlet's service");
  22.           /*
  23.           * 一、绘图
  24.           */
  25.           /*
  26.           * step1,创建一个内存映像对象(画布)
  27.           * BufferedImage(宽度,高度,类型)
  28.           */
  29.           BufferedImage image =
  30.                new BufferedImage(80,30,
  31.                          BufferedImage.TYPE_INT_RGB);
  32.           /*
  33.           * step2,获得一个画笔
  34.           */
  35.           Graphics g = image.getGraphics();
  36.           /*
  37.           * step3,给笔设置颜色
  38.           */
  39.           Random r = new Random();
  40.           g.setColor(new Color(255,255,255));
  41.           /*
  42.           * step4,给画布设置背景颜色
  43.           * fillRect(x,y,width,height)
  44.           */
  45.           g.fillRect(0, 0, 80, 30);
  46.           /*
  47.           * step5,绘图
  48.           */
  49.           g.setColor(new Color(r.nextInt(255),
  50.                     r.nextInt(255),r.nextInt(255)));
  51.           //Font(字体,风格,大小)
  52.           g.setFont(new Font(null,Font.ITALIC,22));
  53.           String number = getNumber(5);
  54.           //将number绑订到session对象上
  55.           HttpSession session =
  56.                request.getSession();
  57.           session.setAttribute("number", number);
  58.           //drawString(String,x,y) x,y是左下角的坐标
  59.           g.drawString(number, 2, 23);
  60.           //step6,加一些干扰线
  61.           for(int i=0;i<6;i++){
  62.                g.drawLine(r.nextInt(80),
  63.                          r.nextInt(30),
  64.                          r.nextInt(80), r.nextInt(30));
  65.           }
  67.           /*
  68.           * 二、将图片压缩并发送给浏览器
  69.           */
  70.           //设置content-type消息头，告诉
  71.           //浏览器返回的是图片
  72.           response.setContentType("image/jpeg");
  73.           //一定要获得字节输出流
  74.           OutputStream ops = response.getOutputStream();
  75.           //write方法会对原始图片(image)按照
  76.           //指定的压缩算法(jpeg)进行压缩，并且
  77.           //将压缩之后的数据输出到指定的流(ops)。
  78.           javax.imageio.ImageIO.write(image, "jpeg", ops);
  79.           ops.close();
  80.      }
  82.      /*
  83.      * 生成一个验证码，该验证码由"A~Z","0~9"中
  84.      随机选取5个字符组成
  85.      */
  86.      private String getNumber(int size) {
  87.           String rs = "";
  88.           String strs = "ABCDEFGHIJKLMNOPQ" +
  89.                     "RSTUVWXYZ0123456789";
  90.           Random r = new Random();
  91.           for(int i=0;i<size;i++){
  92.                rs += strs.charAt(r.nextInt(strs.length()));
  93.           }
  94.           return rs;
  95.      }
  96. }

前台的验证码的获取方式

  1.  $(this).find( "img").attr("src" ,"../getcode.htm?num=" +num);