java之验证码

最新推荐文章于 2025-07-30 16:47:17 发布

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最新推荐文章于 2025-07-30 16:47:17 发布

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CC 4.0 BY-SA版权

文章标签： java

原文链接：http://www.cnblogs.com/yx512/archive/2013/04/12/3016278.html

本文介绍了一种使用Java生成随机验证码图片的方法。该方法通过创建带有随机字符和干扰线的图片来提高安全性。文章详细展示了如何设置图片尺寸、字体、颜色及字符生成等步骤。

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package action;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class RandomValidateCode {
     public static final String RANDOMCODEKEY = "RANDOMVALIDATECODEKEY";//放到session中的key
        private Random random = new Random();
        private String randString = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";//随机产生的字符串
        
        private int width = 80;//图片宽
        private int height = 26;//图片高
        private int lineSize = 40;//干扰线数量
        private int stringNum = 4;//随机产生字符数量
        /*
         * 获得字体
         */
        private Font getFont(){
            return new Font("Fixedsys",Font.CENTER_BASELINE,18);
        }
        /*
         * 获得颜色
         */
        private Color getRandColor(int fc,int bc){
            if(fc > 255)
                fc = 255;
            if(bc > 255)
                bc = 255;
            int r = fc + random.nextInt(bc-fc-16);
            int g = fc + random.nextInt(bc-fc-14);
            int b = fc + random.nextInt(bc-fc-18);
            return new Color(r,g,b);
        }
        /**
         * 生成随机图片
         */
        public void getRandcode(HttpServletRequest request,
                HttpServletResponse response) {
            HttpSession session = request.getSession();
            //BufferedImage类是具有缓冲区的Image类,Image类是用于描述图像信息的类
            BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_BGR);
            Graphics g = image.getGraphics();//产生Image对象的Graphics对象,改对象可以在图像上进行各种绘制操作
            g.fillRect(0, 0, width, height);
            g.setFont(new Font("Times New Roman",Font.ROMAN_BASELINE,18));
            g.setColor(getRandColor(110, 133));
            //绘制干扰线
            for(int i=0;i<=lineSize;i++){
                drowLine(g);
            }
            //绘制随机字符
            String randomString = "";
            for(int i=1;i<=stringNum;i++){
                randomString=drowString(g,randomString,i);
            }
            session.removeAttribute(RANDOMCODEKEY);
            session.setAttribute(RANDOMCODEKEY, randomString);
            System.out.println(randomString);
            g.dispose();
            try {
                ImageIO.write(image, "JPEG", response.getOutputStream());//将内存中的图片通过流动形式输出到客户端
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        /*
         * 绘制字符串
         */
        private String drowString(Graphics g,String randomString,int i){
            g.setFont(getFont());
            g.setColor(new Color(random.nextInt(101),random.nextInt(111),random.nextInt(121)));
            String rand = String.valueOf(getRandomString(random.nextInt(randString.length())));
            randomString +=rand;
            g.translate(random.nextInt(3), random.nextInt(3));
            g.drawString(rand, 13*i, 16);
            return randomString;
        }
        /*
         * 绘制干扰线
         */
        private void drowLine(Graphics g){
            int x = random.nextInt(width);
            int y = random.nextInt(height);
            int xl = random.nextInt(13);
            int yl = random.nextInt(15);
            g.drawLine(x, y, x+xl, y+yl);
        }
        /*
         * 获取随机的字符
         */
        public String getRandomString(int num){
            return String.valueOf(randString.charAt(num));
        }

}