SSM生成简单验证码，并集成到项目中

最近一段时间都在忙到做期末项目，目前做到用户留言板功能，所以防止用户恶意提交留言，所以打算加入验证码功能，以下就是生成简单的验证码，代码复制即可使用！

前端效果如下：

前端jsp页面代码：

<div class="layui-form-item">
   <label class="layui-form-label">验证码</label>
   <div class="layui-input-inline">
   <input type="text" name="inputCode" lay-verify="required" placeholder="请输入验证码" class="layui-input">
   </div>
   <img src="这里填验证码生成接口" alt="" width="100" height="38px" class="passcode" style="height:38px;cursor:pointer;" onclick="this.src=this.src+'?'">
</div>

后端首先创建一个生成验证码的工具类：RandomValidateCode.class

/**
 * @author lcry
 * @create 2018/12/29
 */
package com.lcry.util;

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;

/**
 * 验证码工具类
 * Created on 2018/12/29.
 *
 * @author lcry
 */
public class RandomValidateCode {

    public static final String RANDOMCODEKEY = "randomcode_key";
   //放到session中的key，到时候从从session取出来和用户输入的进行对比
    private Random random = new Random();
    private String randString = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";//随机产生的字符串

    private int width = 80;//图片宽
    private int height = 26;//图片高
    private int lineSize = 40;//干扰线数量
    private int stringNum = 4;//随机产生字符数量

    /**
     * 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);
        //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
        Graphics g = image.getGraphics();
        g.fillRect(0, 0, width, height);
        g.setFont(new Font("Times New Roman", Font.ROMAN_BASELINE, 18));
        g.setColor(getRandColor(160, 200));
        //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);
        }
        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();
        }
    }

    /*
     * 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);
    }

    /*
     * 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));
    }
}

验证码生成接口：

   /**
     * 获取生成验证码显示到 UI 界面
     *
     * @param request
     * @param response
     * @throws ServletException
     * @throws IOException
     */
    @RequestMapping(value = "/checkCode")
    public void checkCode(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        //设置相应类型,告诉浏览器输出的内容为图片
        response.setContentType("image/jpeg");

        //设置响应头信息，告诉浏览器不要缓存此内容
        response.setHeader("pragma", "no-cache");
        response.setHeader("Cache-Control", "no-cache");
        response.setDateHeader("Expire", 0);

        RandomValidateCode randomValidateCode = new RandomValidateCode();
        try {
            randomValidateCode.getRandcode(request, response);//输出图片方法
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

最后进行在项目中使用即可(只粘贴核心代码)：

@RequestMapping(value = "addureq")
    @ResponseBody
    public String insertureq(Mureq mureq, HttpServletResponse response, HttpServletRequest req,
                             @RequestParam(value = "inputCode") String inputCode) throws Exception {
        // 获取存放在session中的验证码
        String code = (String) req.getSession().getAttribute("randomcode_key");
        System.out.println("验证码对比"+code+inputCode);
        // 获取页面提交的验证码
        JSONObject result = new JSONObject();
        if (code.toLowerCase().equals(inputCode.toLowerCase())) {// 验证码不区分大小写
            boolean istrue = mureqService.insertreq(mureq);
            if (istrue) {
                result.put("msg", "留言成功");
            } else {
                result.put("msg", "留言失败");
            }
        } else { // 验证失败
            result.put("msg", "验证码错误");
        }
        ResponseUtil.write(response, result);
        return null;
    }

参考链接：
https://blog.csdn.net/zys15256630193/article/details/80518800
https://blog.csdn.net/sinat_32133675/article/details/77247892
https://blog.csdn.net/yhflyl/article/details/80944684