SpringBoot实现简单的登录验证码

参考了一些资料，完成了这个验证码的功能，下面记录一下功能的实现过程。

参考自：blog.csdn.net/Colton_Null…

一、效果图

二、实现原理

后台生成验证码图片，将图片传到前台。
后台在session中保存验证码内容。
前台输入验证码后传到后台在后台取出session中保存的验证码进行校验。

三、代码

首先是图片生成的工具类：

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.util.Random;

public class RandomValidateCodeUtil {


    public static final String RANDOMCODEKEY = "RANDOMVALIDATECODEKEY";//放到session中的key
    private String randString = "0123456789";//随机产生只有数字的字符串 private String
    //private String randString = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";//随机产生只有字母的字符串
    //private String randString = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";//随机产生数字与字母组合的字符串
    private int width = 95;// 图片宽
    private int height = 25;// 图片高
    private int lineSize = 40;// 干扰线数量
    private int stringNum = 4;// 随机产生字符数量

    private Random random = new Random();

    /**
     * 获得字体
     */
    private Font getFont() {
        return new Font("Fixedsys", Font.CENTER_BASELINE, 18);
    }

    /**
     * 获得颜色
     */
    private Color getRandColor(int fc, int bc) {
        if (fc > 255)
            fc = 255;
        if (bc > 255)
            bc = 255;
        int r = fc + random.nextInt(bc - fc - 16);
        int g = fc + random.nextInt(bc - fc - 14);
        int b = fc + random.nextInt(bc - fc - 18);
        return new Color(r, g, b);
    }

    /**
     * 生成随机图片
     */
    public void getRandcode(HttpServletRequest request, HttpServletResponse response) {
        HttpSession session = request.getSession();
        // BufferedImage类是具有缓冲区的Image类,Image类是用于描述图像信息的类
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_BGR);
        Graphics g = image.getGraphics();// 产生Image对象的Graphics对象,改对象可以在图像上进行各种绘制操作
        g.fillRect(0, 0, width, height);//图片大小
        g.setFont(new Font("Times New Roman", Font.ROMAN_BASELINE, 18));//字体大小
        g.setColor(getRandColor(110, 133));//字体颜色
        // 绘制干扰线
        for (int i = 0; i <= lineSize; i++) {
            drowLine(g);
        }
        // 绘制随机字符
        String randomString = "";
        for (int i = 1; i <= stringNum; i++) {
            randomString = drowString(g, randomString, i);
        }
        System.out.println(randomString);
        //将生成的随机字符串保存到session中
        session.removeAttribute(RANDOMCODEKEY);
        session.setAttribute(RANDOMCODEKEY, randomString);
        g.dispose();
        try {
            // 将内存中的图片通过流动形式输出到客户端
            ImageIO.write(image, "JPEG", response.getOutputStream());
        } catch (Exception e) {
            e.printStackTrace();
        }

    }

    /**
     * 绘制字符串
     */
    private String drowString(Graphics g, String randomString, int i) {
        g.setFont(getFont());
        g.setColor(new Color(random.nextInt(101), random.nextInt(111), random
                .nextInt(121)));
        String rand = String.valueOf(getRandomString(random.nextInt(randString
                .length())));
        randomString += rand;
        g.translate(random.nextInt(3), random.nextInt(3));
        g.drawString(rand, 13 * i, 16);
        return randomString;
    }

    /**
     * 绘制干扰线
     */
    private void drowLine(Graphics g) {
        int x = random.nextInt(width);
        int y = random.nextInt(height);
        int xl = random.nextInt(13);
        int yl = random.nextInt(15);
        g.drawLine(x, y, x + xl, y + yl);
    }

    /**
     * 获取随机的字符
     */
    public String getRandomString(int num) {
        return String.valueOf(randString.charAt(num));
    }
}

Controller中将验证码图片传给前台界面

 /**
     * 生成验证码
     */
    @RequestMapping(value = "/getVerify")
    public void getVerify(HttpServletRequest request, HttpServletResponse response) {
        try {
            response.setContentType("image/jpeg");//设置相应类型,告诉浏览器输出的内容为图片
            response.setHeader("Pragma", "No-cache");//设置响应头信息，告诉浏览器不要缓存此内容
            response.setHeader("Cache-Control", "no-cache");
            response.setDateHeader("Expire", 0);
            RandomValidateCodeUtil randomValidateCode = new RandomValidateCodeUtil();
            randomValidateCode.getRandcode(request, response);//输出验证码图片方法
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

前台界面

<div class="row">
    <div class="col-xs-6 pull_left">
        <form action="/checkVerify">
            <div class="form-group">
                <input class="form-control" type="tel" id="verify_input" name="code" placeholder="请输入验证码" maxlength="4">
            </div>
            <div class="form-group">
                <button type="submit">提交</button>
            </div>
        </form>
    </div>
    <div class="col-xs-6 pull_left">
        <a href="javascript:void(0);" title="点击更换验证码">
            <img id="imgVerify" src="" alt="更换验证码" height="36" width="100px" onclick="getVerify(this);">
        </a>
    </div>
    <script>
        function getVerify(obj) {
            obj.src = "/getVerify?" + Math.random();
        }
    </script>
</div>

后台检查验证码

@RequestMapping(value = "/checkVerify")
    public boolean checkVerify(String code, HttpSession session) {
        try {
            //从session中获取随机数
            String random = (String) session.getAttribute("RANDOMVALIDATECODEKEY");
            if (random == null) {
                return false;
            }
            if (random.equals(code)) {
                System.out.println("正确的验证码");
                return true;
            } else {
                System.out.println("错误的验证码");
                return false;
            }
        } catch (Exception e) {
            e.printStackTrace();
            return false;
        }
    }