Servlet生成验证码案例

说明:

1. 浏览器访问服务器自动生成一张验证码图片到前台页面;

2. 点击图片或者旁边的超链接会更新验证码图片;

3. 代码实现:

     Java: servlet + BufferedImage类创建图片对象 + 随机数生成 + "画笔类"Graphics画图

     JavaScript: Date对象 + 图片标签添加单击事件 + a标签添加单击事件且页面不跳转

4. 技巧: a标签点击触发单击事件但页面不发生跳转  :

XXX

源码:

后台servlet   CheckCodeServlet.java

package com.zzuli.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;

/**
 * Created by hejjon on 2019/6/26 22:54.
 *  验证码简单实现
 */
@WebServlet("/checkCodeServlet")
public class CheckCodeServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 图片的宽高
        int width = 100;
        int height = 50;

        // 创建验证码图片对象
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

        // 填充背景色
        Graphics g = image.getGraphics();
        g.setColor(Color.PINK);
        g.fillRect(0, 0, width, height);

        // 画边框
        g.setColor(Color.BLUE);
        g.drawRect(0, 0, width - 1, height - 1);


        // 写验证码
        String str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
        Random random = new Random();
        for (int i = 1; i <= 4; i++) {
            int index = random.nextInt(str.length());       // 随机生成脚标
            char ch = str.charAt(index);
            g.drawString(ch + "", width / 5 * i, height / 2);
        }

        // 画线
        g.setColor(Color.GREEN);

        for (int i = 0; i < 10; i++) {
            int x1 = random.nextInt(width);
            int x2 = random.nextInt(width);
            int y1 = random.nextInt(height);
            int y2 = random.nextInt(height);
            g.drawLine(x1, y1, x2, y2);
        }

        // 将图片输出到页面
        ImageIO.write(image, "jpg", response.getOutputStream());

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request, response);
    }
}

前台html页面    register.html

    
    
    


    

    看不清换一张

 效果展示:

欢迎指出错误, 感谢!!!  

 

...完