Servlet在界面当中实现图片验证码

小咪咪 2023-02-25 02:03 10阅读 0赞

Servlet实现在界面中显示图片验证码功能  
创建验证码生成的工具类…方便调用

import java.awt.*;
    import java.awt.image.BufferedImage;
    import java.util.*;
    
    /** * @program: ServletDom * @description: 验证码生成工具类 **/
    public class VerifyCodeUtil { 
        private static final Integer W=100; //设置宽度
        private static final Integer H=40;  //设置高度
        //设置验证码生成库
        private static final String CODE = "abcdefghijkimnABCDEFGHIJKIMN0123456789";
        //设置验证码的字符数量
        private static final Integer CODE_COUNT = 4;
        //干扰线的数量
        private static final Integer LINE_COUNT = 4;
    
        //创建随机数对象
        static Random random = new Random();
    
        /** * 封装获取Map键值对 * @return */
        public static Map<String, BufferedImage> getMap(){ 
            //构建一张空白透明的图片，用来生成验证码
            BufferedImage image = new BufferedImage(W,H,BufferedImage.TYPE_INT_BGR);
            //创建画笔；
            Graphics g = image.getGraphics();
            //设置画笔的颜色
            g.setColor(getColor());//存放随机颜色
            //给图片填充背景色
            g.fillRect(0,0,W,H);
            //创建字体对象
            Font font = new Font("黑体",Font.BOLD,25);
            //设置字体
            g.setFont(font);
            //创建可追加字符对象
            StringBuffer sb = new StringBuffer();
            //循环写入验证码
            for (int i=0;i<CODE_COUNT;i++){ 
                //设置画笔颜色，写入字体的颜色
                g.setColor(getColor());
                //获取验证码字符
                char c = getChar();
                //绘制到图片中 位置 高度
                g.drawString(c+"",i*20+5,25);
                //c+""：将参数c装换成字符串
                sb.append(c);
            }
            //绘制干扰线
            for (int i = 0; i < LINE_COUNT; i++) { 
                //设置画笔颜色
                g.setColor(getColor());
                //两点确定一条线
                int xStart=random.nextInt(W+1);
                int yStart=random.nextInt(H+1);
                int xEnd=random.nextInt(W+1);
                int yEnd=random.nextInt(H+1);
                //绘制线条
                g.drawLine(xStart, yStart, xEnd, yEnd);
            }
            //画噪点
            int total = (int) (W*H*0.02);
            for (int i = 0; i < total; i++) { 
                //设置画笔颜色
                g.setColor(getColor());
                int x = random.nextInt(W);
                int y = random.nextInt(H);
                //绘制点
                image.setRGB(x,y,getColor().getRGB());
            }
            Map<String,BufferedImage> map = new HashMap<>();
            map.put(sb.toString(),image);
            return map;
        }
        //封装得到图片静态方法
        public static BufferedImage getImage(Map<String,BufferedImage> map){ 
            Set<Map.Entry<String,BufferedImage>> set = map.entrySet();
            //得到set迭代器
            Iterator<Map.Entry<String, BufferedImage>> iterator = set.iterator();
            //由于此处mao只有一组织，直接得到键值对
            Map.Entry<String,BufferedImage> entry = iterator.next();
            return entry.getValue();
        }
        //封装得到数值静态方法
        public static String getCode(Map<String,BufferedImage> map){ 
            Set<Map.Entry<String,BufferedImage>> set = map.entrySet();
            //得到set迭代器
            Iterator<Map.Entry<String, BufferedImage>> iterator = set.iterator();
            //由于此处mao只有一组织，直接得到键值对
            Map.Entry<String,BufferedImage> entry = iterator.next();
            return entry.getKey();
        }
        /** * 封装随机获取颜色 * @return */
        private static Color getColor(){ 
            return new Color(random.nextInt(256),random.nextInt(256),random.nextInt(256));
        }
    
        /** * 封装获取验证码字符方法 * @return */
        private static char getChar(){ 
            //在仓库CODE中随机获取一个
            return CODE.charAt(random.nextInt(36));
        }
    }

Servlet控制器 在这里向网页传输图片

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 java.awt.image.BufferedImage;
    import java.io.IOException;
    import java.util.Map;
    
    /** * @program: ServletDom * @description: 验证码图片servlet **/
    @WebServlet("/imgCode")
    public class ImageCodeServlet extends HttpServlet { 
        @Override
        public void service(HttpServletRequest request, HttpServletResponse response)
                throws IOException, ServletException { 
            //设置响应格式
            response.setContentType("image/jpeg");
            //获得验证码的map
            Map<String, BufferedImage> map = VerifyCodeUtil.getMap();
            //获取map中的图片
            BufferedImage img = VerifyCodeUtil.getImage(map);
            //获取map中的数据
            String code = VerifyCodeUtil.getCode(map);
            System.out.println(code);
            //将图片放入输出流中，写到网页上
            ImageIO.write(img,"jpeg",response.getOutputStream());
        }
    }