1.java代码
1 import java.awt.Color;
2 import java.awt.Font;
3 import java.awt.Graphics;
4 import java.awt.image.BufferedImage;
5 import java.io.IOException;
6 import java.util.Random;
7 import javax.imageio.ImageIO;
8 import javax.servlet.ServletException;
9 import javax.servlet.http.HttpServlet;
10 import javax.servlet.http.HttpServletRequest;
11 import javax.servlet.http.HttpServletResponse;
12
13 public class ImageServlet extends HttpServlet{
14 @Override
15 public void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
16 //通知浏览器不要缓存
17 resp.setHeader("Expires", "-1");
18 resp.setHeader("Cache-Control", "no-cache");
19 resp.setHeader("Prama", "no-cache");
20
21 String code = req.getParameter("code"); //接受jsp页面表单填入的验证码
22 int width=120;
23 int height=50;
24 //在内存中创建一幅图
25 BufferedImage bu = new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB);
26 //得到一个画笔
27 Graphics gr = bu.getGraphics();
28 //画边框
29 gr.setColor(Color.gray);
30 gr.drawRect(0, 0, width, height);
31 //背景
32 gr.setColor(Color.pink);
33 gr.fillRect(1, 1, width-2, height-2);
34 //干扰线
35 Random ran = new Random();
36 gr.setColor(Color.black);
37 for(int i=0;i<=10;i++){
38 gr.drawLine(ran.nextInt(width), ran.nextInt(height), ran.nextInt(width), ran.nextInt(height));
39 }
40 //验证码
41 gr.setColor(Color.red);
42 gr.setFont(new Font("宋体", Font.BOLD|Font.ITALIC, 35));
43 int x =18;
44 String s =""; //接收随机生成的验证码
45 for(int j=0;j<4;j++){
46 s+=ran.nextInt(10)+"";
47 gr.drawString(s.substring(j,j+1), x, 35);
48 x+=25;
49 }
50 req.getSession().setAttribute("racode", s); //
51 //System.out.println(s);
52 if(code.equals(s)){ // 对比检测前端与后端的验证码是否一致
53 System.out.println("验证码输入正确");
54 }else{
55 System.out.println("验证码输入错误");
56 }
57 //输出到网页上
58 ImageIO.write(bu, "jpg", resp.getOutputStream());
59 }
60 @Override
61 public void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
62 this.doGet(req, resp);
63 }
64 }
2.jsp代码
1 <%@ page language="java" contentType="text/html" pageEncoding="UTF-8"%>
2 <!DOCTYPE html>
3 <html>
4 <head>
5 <title>验证码</title>
6 <script type="text/javascript">
7 function tofresh(){
8 document.location.href="ImageLogin.jsp";
9 }
10
11 </script>
12 </head>
13 <body>
14 <form action="ImageServlet" method="post">
15 用户名<input type="text" name="username"><br/>
16 密码<input type="password" name="pass"><br/>
17 验证码<input type="text" name="code"><br/>
18 <img alt="验证码" src="/WEB/ImageServlet">
19 <a href="javascript:tofresh()">看不清，请再换一张</a>
20 </form>
21 </body>
22 </html>
3.配置web.xml 文件
1 <servlet> 2 <servlet-name>ImageServlet</servlet-name> 3 <servlet-class>ImageServlet</servlet-class> 4 </servlet> 5 <servlet-mapping> 6 <servlet-name>ImageServlet</servlet-name> 7 <url-pattern>/code</url-pattern> 8 </servlet-mapping>
原文地址：https://www.cnblogs.com/liuyangv/p/8120470.html
时间： 2024-10-13 00:03:02