JavaWeb项目中生成验证码

野性酷女 2022-09-26 02:55 204阅读 0赞

## 在项目中使用servlet随机生成验证码 ##

1.在jsp页面中验证码图片加入img标签，src为生成验证码的servlet的url;

2.在servlet中生成随机验证码

public class AuthCode extends HttpServlet { 
        private static final int WIDTH = 60;//设置验证码图片宽度
        private static final int HEIGHT = 20;//设置验证码图片高度
        private static final int LENGTH = 4;//设置验证码长度
        //设置验证码随机出现的字符
        private static final String str = "1234567890" +
                "abcdefghijklmnopqrstuvwxyz" +
                "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        char[] chars = str.toCharArray();//将字符放在数组中方便随机读取
        private static Random random = new Random();
    
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    
            //设置输出的类型为图片
            response.setContentType("image/jpeg");
    
            //设置不进行缓存
            response.setHeader("pragma", "no-cache");
            response.setHeader("cache-control", "no-cache");
            response.setHeader("expires", "0");
    
            BufferedImage image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_3BYTE_BGR);
    
            //画笔
            Graphics graphics = image.getGraphics();
    
            //设置背景颜色并绘制矩形背景
            graphics.setColor(Color.WHITE);
            graphics.fillRect(0, 0, WIDTH, HEIGHT);
    
            //用于记录生成的验证码
            String code = null;
    
            //生成验证码并绘制
            for (int i = 0; i < LENGTH; i++) {
                String c = "" + chars[random.nextInt(str.length())];
                graphics.setColor(getColor());
                graphics.drawString(c, 10 * i + 10, 18);
                code += c;
            }
    
            //生成干扰点
            for (int i = 0; i < 50; i++) {
                graphics.setColor(getColor());
                graphics.drawOval(random.nextInt(60), random.nextInt(20), 1, 1);
            }
    
            //将生成的验证码存入session中，以便进行校验
            HttpSession session = request.getSession();
            session.setAttribute("code", code);
    
            //绘制图片
            graphics.dispose();
    
            //将图片输出到response中
            ImageIO.write(image, "JPEG", response.getOutputStream());
        }
    
        //随机生成颜色
        private Color getColor() {
            return new Color(random.nextInt(255), random.nextInt(255), random.nextInt(255));
        }
    }

3.为img标签添加onclick事件，点击更新验证码

--------------------

## 文件： ##

*  web.xml

<?xml version="1.0" encoding="UTF-8"?>
    <web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" version="3.1">
        <servlet>
            <servlet-name>AuthCode</servlet-name>
            <servlet-class>AuthCode</servlet-class>
        </servlet>
        <servlet-mapping>
            <servlet-name>AuthCode</servlet-name>
            <url-pattern>/code</url-pattern>
        </servlet-mapping>
    </web-app>

*  index.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
    <html>
      <head>
        <title>验证码</title>
      </head>
      <body>
      <img id="codeImg" src="/AuthCode/code" onclick="refreshCode()">
      </body>
    <script type="text/javascript"> function refreshCode() { var codeImg = document.getElementById("codeImg"); var d = new Date(); codeImg.src = "/AuthCode/code?s="+d; } </script>
    </html>

*  AuthCode.java

import javax.imageio.ImageIO;
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import javax.servlet.http.HttpSession;
    import java.awt.*;
    import java.awt.image.BufferedImage;
    import java.io.IOException;
    import java.util.Random;
    
    @WebServlet(name = "AuthCode")
    public class AuthCode extends HttpServlet { 
        private static final int WIDTH = 60;//设置验证码图片宽度
        private static final int HEIGHT = 20;//设置验证码图片高度
        private static final int LENGTH = 4;//设置验证码长度
        //设置验证码随机出现的字符
        private static final String str = "1234567890" +
                "abcdefghijklmnopqrstuvwxyz" +
                "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        char[] chars = str.toCharArray();//将字符放在数组中方便随机读取
        private static Random random = new Random();
    
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    
            //设置输出的类型为图片
            response.setContentType("image/jpeg");
    
            //设置不进行缓存
            response.setHeader("pragma", "no-cache");
            response.setHeader("cache-control", "no-cache");
            response.setHeader("expires", "0");
    
            BufferedImage image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_3BYTE_BGR);
    
            //画笔
            Graphics graphics = image.getGraphics();
    
            //设置背景颜色并绘制矩形背景
            graphics.setColor(Color.WHITE);
            graphics.fillRect(0, 0, WIDTH, HEIGHT);
    
            //用于记录生成的验证码
            String code = null;
    
            //生成验证码并绘制
            for (int i = 0; i < LENGTH; i++) {
                String c = "" + chars[random.nextInt(str.length())];
                graphics.setColor(getColor());
                graphics.drawString(c, 10 * i + 10, 18);
                code += c;
            }
    
            //生成干扰点
            for (int i = 0; i < 50; i++) {
                graphics.setColor(getColor());
                graphics.drawOval(random.nextInt(60), random.nextInt(20), 1, 1);
            }
    
            //将生成的验证码存入session中，以便进行校验
            HttpSession session = request.getSession();
            session.setAttribute("code", code);
    
            //绘制图片
            graphics.dispose();
    
            //将图片输出到response中
            ImageIO.write(image, "JPEG", response.getOutputStream());
        }
    
        //随机生成颜色
        private Color getColor() {
            return new Color(random.nextInt(255), random.nextInt(255), random.nextInt(255));
        }
    }

## [项目下载][Link 1] ##

[Link 1]: http://download.csdn.net/detail/u013360850/9633090