随机生成图片验证码

springboot + jq 随机生成图片验证码 

效果如下

 

1.前端 html

2.前端 js 

$(function(){
     //首次获取验证码
     $("#random_pic").attr("src","/util/getVerify.html?"+Math.random());
});

function getVerify(obj){
     //点击获取验证码
     obj.src = "/util/getVerify.html?"+Math.random();
}

3.后台 生成随机验证码图片

1)图片名是picName, 保存在session里, 供校验使用

2)图片本身是img, 写入输出流, 给前端显示 (图片保存在内存中)

package com.prj.utils;

import com.prj.commons.Constants;
import lombok.extern.slf4j.Slf4j;

import javax.imageio.ImageIO;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

/**
 * Created by Alwen
 * 2018/11/13 15:02
 */
@Slf4j
//生成随机验证码
public class RandomPic {

    private static Random random = new Random();
    private static int width = 120;
    private static int height = 50;
    private static String str = "abcdefghjkmnpqrstuvwxyz23456789";    //允许在图片内显示的字符

    private static int randomNum(int min, int max) {
        int num = 0;
        num = random.nextInt(max - min) + min;
        return num;
    }

    //设置颜色
    private static Color setColor(int min, int max) {
        int r = min + random.nextInt(max - min);
        int g = min + random.nextInt(max - min);
        int b = min + random.nextInt(max - min);
        return new Color(r, g, b);
    }

    public static void getPic(HttpServletRequest request,
                              HttpServletResponse response) throws IOException {
        //在内存中创建图片
        BufferedImage img = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        //在图片上画一个矩形当背景
        Graphics g = img.getGraphics();
        g.setColor(setColor(150, 230));
        g.fillRect(0, 0, width, height);

        //生成的字符串
        String picName = "";
        for (int i = 0; i < 4; i++) {
            g.setColor(setColor(30, 140));
            g.setFont(new Font("黑体", Font.PLAIN, 40));
            char c = str.charAt(randomNum(0, str.length()));
            g.drawString(String.valueOf(c), 10 + i * 30, randomNum(height - 30, height));
            picName += c;
        }

        //画随机线
        for (int i = 0; i < 25; i++) {
            g.setColor(setColor(50, 180));
            g.drawLine(randomNum(0, width), randomNum(0, height), randomNum(0, width), randomNum(0, height));
        }

        //把内存中创建的图像输出到文件中
//        File file = new File("C:/Users/AlwenZwei/Desktop/mk_file/vcode.png");
//        ImageIO.write(img, "png", file);

        //把图片创建在内存中
        ImageIO.write(img, "JPEG", response.getOutputStream());
        log.info("图片: " + picName);
        HttpSession session = request.getSession();
        session.setAttribute(Constants.RANDOM_PIC, picName);
    }
}

4.前端getVerify调用方法, 获取随机图片

@RequestMapping("/getVerify.html")
    public void getVerify(HttpServletRequest request, HttpServletResponse response) {
        //设置相应信息
        response.setContentType("image/jpeg");
        response.setHeader("Pragma", "No-cache");
        response.setHeader("Cache-Control", "no-cache");
        response.setDateHeader("Expire", 0);
        try {
            //输出图片
            RandomPic.getPic(request, response);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

至此, 图片已经输出到img标签, 图片的内容保存在session中, 通过ajax可以进行校验