字符型验证码的编写和使用

朴灿烈づ我的快乐病毒、 2022-03-21 15:16 233阅读 0赞

新建一个servlet，用于产生验证码：

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.*;
    import java.awt.image.BufferedImage;
    import java.io.IOException;
    import java.util.Random;
    
    @WebServlet(urlPatterns = "/code")
    public class CodeServlet1 extends HttpServlet {
    
        @Override
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            int codeLength = 4;
            int width=20*4;
            int height=30;
            //1.创建一张内存图片
            BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
            //2.获取画笔工具
            Graphics gh = image.getGraphics();
            //3.绘制背景
            Random random = new Random();//用于随机产生颜色
            gh.setColor(new Color(random.nextInt(255),random.nextInt(255),random.nextInt(255)));
            gh.fillRect(0,0,width,height);
            //4.绘制边框
            gh.setColor(new Color(random.nextInt(255),random.nextInt(255),random.nextInt(255)));
            gh.drawRect(0,0,width-1,height-1);
            //5.绘制验证码
            String source = "ABCDEFGHGKLMNPQRSTUVWXYZ23456789";
            gh.setFont(new Font("宋体",Font.BOLD,22));
            String code = "";
            for (int i = 0; i < codeLength; i++) {
                String letter = String.valueOf(source.charAt(random.nextInt(32)));
                gh.setColor(new Color(random.nextInt(255),random.nextInt(255),random.nextInt(255)));
                gh.drawString(letter,5+20*i,22);
                code += letter;
            }
            //6.保存到session中以备验证时使用
            request.getSession().setAttribute("code",code);
            //7.绘制干扰线
            gh.setColor(new Color(random.nextInt(255),random.nextInt(255),random.nextInt(255)));
            for (int i = 0; i < codeLength; i++) {
                gh.drawLine(random.nextInt(width),random.nextInt(height),random.nextInt(width),random.nextInt(height));
            }
            //8.释放资源
            gh.dispose();
            //9.输出图片
            ImageIO.write(image,"jpg",response.getOutputStream());
        }
    
        @Override
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    
        }
    }

在jsp中使用验证码

局部刷新换一张验证码