随机生成验证码

来源：互联网发布：淘宝没有销量编辑：程序博客网时间：2024/06/05 23:22

package com.CodeServle;import java.awt.Color;import java.awt.Font;import java.awt.Graphics;import java.awt.Graphics2D;import java.awt.image.BufferedImage;import java.io.IOException;import java.util.Random;import javax.imageio.ImageIO;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class CodeServlet extends HttpServlet {            public void doGet(HttpServletRequest request, HttpServletResponse response)                throws ServletException, IOException {                // 使用java图形界面技术绘制一张图片                int charNum = 4;                int width = 30 * 4;                int height = 30;                // 1. 创建一张内存图片                BufferedImage bufferedImage = new BufferedImage(width, height,                        BufferedImage.TYPE_INT_RGB);                // 2.获得绘图对象                Graphics graphics = bufferedImage.getGraphics();                // 3、绘制背景颜色                graphics.setColor(Color.YELLOW);                graphics.fillRect(0, 0, width, height);                // 4、绘制图片边框                graphics.setColor(Color.BLUE);                graphics.drawRect(0, 0, width - 1, height - 1);                // 5、输出验证码内容                graphics.setColor(Color.RED);                graphics.setFont(new Font("宋体", Font.BOLD, 20));                // 随机输出4个字符                Graphics2D graphics2d = (Graphics2D) graphics;                 String s = "ABCDEFGHGKLMNPQRSTUVWXYZ23456789";                Random random = new Random();                //session中要用到                String msg="";                int x = 5;                for (int i = 0; i < 4; i++) {                    int index = random.nextInt(32);                    String content = String.valueOf(s.charAt(index));                    msg+=content;                    double theta = random.nextInt(45) * Math.PI / 180;                    //让字体扭曲                    graphics2d.rotate(theta, x, 18);                    graphics2d.drawString(content, x, 18);                    graphics2d.rotate(-theta, x, 18);                    x += 30;                }                // 6、绘制干扰线                graphics.setColor(Color.GRAY);                for (int i = 0; i < 5; i++) {                    int x1 = random.nextInt(width);                    int x2 = random.nextInt(width);                    int y1 = random.nextInt(height);                    int y2 = random.nextInt(height);                    graphics.drawLine(x1, y1, x2, y2);                }                // 释放资源                graphics.dispose();                // 图片输出 ImageIO                ImageIO.write(bufferedImage, "jpg", response.getOutputStream());            }        public void doPost(HttpServletRequest request, HttpServletResponse response)                throws ServletException, IOException {        }    }

> web.xmlxml文件中配置CodeServlet  <servlet>    <description></description>    <display-name>CodeServlet</display-name>    <servlet-name>CodeServlet</servlet-name>    <servlet-class>com.CodeServlet</servlet-class>  </servlet>  <servlet-mapping>    <servlet-name>CodeServlet</servlet-name>    <url-pattern>/code</url-pattern>  </servlet-mapping>

> code.hmtl<!DOCTYPE html><html><head><meta charset="UTF-8"><title>Insert title here</title></head><body>    <img alt="验证码" src="/code" title="看不清换一张" onclick="changeImg(this)"></body><!--图片是静态资源，会缓存到本地，每次请求会把最后修改时间带过去，如果没有修改图片名则读缓存，所以，每次生成的验证码图片名，加入一个变化的参数，使参数名发生改变，造成每次请求图片名都修改的假象 --><script type="text/javascript">function changeImg(obj){    obj.src="/code?i="+Math.random();}</script></html>

结果展示：
这里写图片描述

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