动态生成验证码案例（Java）

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servlet代码

package cn.guizimo.web.servlet;

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("/checkCode")
public class CheckCode extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        int width = 100;
        int height = 50;
        //创建图片对象
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_BGR);

        //美化
        Graphics g = image.getGraphics();
        //背景
        g.setColor(Color.PINK);
        g.fillRect(0, 0, width, height);
        //边框
        g.setColor(Color.BLUE);
        g.drawRect(0, 0, width - 1, height - 1);

        String str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
        Random ran = new Random();
        for (int i = 1; i <= 4; i++) {
            int index = ran.nextInt(str.length());
            char ch = str.charAt(index);
            g.drawString(ch+"",width/5*i,height/2);
        }

        //干扰线
        g.setColor(Color.GREEN);
        for (int i = 0; i < 10; i++) {
            int x1 = ran.nextInt(width);
            int x2= ran.nextInt(width);
            int y1 = ran.nextInt(height);
            int y2 = ran.nextInt(height);
            g.drawLine(x1,y1,x2,y2);
        }


   //输出图片到浏览器
        ImageIO.write(image, "jpg", resp.getOutputStream());

    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doPost(req, resp);
    }
}

html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script>

        window.onload = function () {
            var img = document.getElementById("checkCode");
            img.onclick = function () {
                var data = new Date().getTime();
                img.src = "/tomcat_test_war_exploded/checkCode?" + data;
            }
        }
    </script>
</head>
<body>
<img id="checkCode" src="/tomcat_test_war_exploded/checkCode"/>
</body>
</html>

启动项目

点击图片可以切换验证码

感谢

黑马程序员

万能的网络

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