，工具类记录

原链接：https://blog.csdn.net/qq_37651267/article/details/99305573，非常感谢原链接博主

此验证码的实现没有用到太多的插件，话不多说直接上代码，大家拿过去就可以用。

1.验证码类

 package com.youyou.login.util.validatecode;

import lombok.Data;

/**
 * 验证码类
 */
@Data
public class VerifyCode {

    private String code;

    private byte[] imgBytes;

    private long expireTime;

}

2.验证码生成接口

 package com.youyou.login.util.validatecode;

import java.io.IOException;
import java.io.OutputStream;

/**
 * 验证码生成接口
 */
public interface IVerifyCodeGen {

    /**
     * 生成验证码并返回code，将图片写的os中
     *
     * @param width
     * @param height
     * @param os
     * @return
     * @throws IOException
     */
    String generate(int width, int height, OutputStream os) throws IOException;

    /**
     * 生成验证码对象
     *
     * @param width
     * @param height
     * @return
     * @throws IOException
     */
    VerifyCode generate(int width, int height) throws IOException;
}

3.验证码生成实现类

 package com.youyou.login.util.validatecode;

import com.youyou.util.RandomUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;

/**
 * 验证码实现类
 */
public class SimpleCharVerifyCodeGenImpl implements IVerifyCodeGen {

    private static final Logger logger = LoggerFactory.getLogger(SimpleCharVerifyCodeGenImpl.class);

    private static final String[] FONT_TYPES = { "\u5b8b\u4f53", "\u65b0\u5b8b\u4f53", "\u9ed1\u4f53", "\u6977\u4f53", "\u96b6\u4e66" };

    private static final int VALICATE_CODE_LENGTH = 4;

    /**
     * 设置背景颜色及大小，干扰线
     *
     * @param graphics
     * @param width
     * @param height
     */
    private static void fillBackground(Graphics graphics, int width, int height) {
        // 填充背景
        graphics.setColor(Color.WHITE);
        //设置矩形坐标x y 为0
        graphics.fillRect(0, 0, width, height);

        // 加入干扰线条
        for (int i = 0; i < 8; i++) {
            //设置随机颜色算法参数
            graphics.setColor(RandomUtils.randomColor(40, 150));
            Random random = new Random();
            int x = random.nextInt(width);
            int y = random.nextInt(height);
            int x1 = random.nextInt(width);
            int y1 = random.nextInt(height);
            graphics.drawLine(x, y, x1, y1);
        }
    }

    /**
     * 生成随机字符
     *
     * @param width
     * @param height
     * @param os
     * @return
     * @throws IOException
     */
    @Override
    public String generate(int width, int height, OutputStream os) throws IOException {
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        Graphics graphics = image.getGraphics();
        fillBackground(graphics, width, height);
        String randomStr = RandomUtils.randomString(VALICATE_CODE_LENGTH);
        createCharacter(graphics, randomStr);
        graphics.dispose();
        //设置JPEG格式
        ImageIO.write(image, "JPEG", os);
        return randomStr;
    }

    /**
     * 验证码生成
     *
     * @param width
     * @param height
     * @return
     */
    @Override
    public VerifyCode generate(int width, int height) {
        VerifyCode verifyCode = null;
        try (
                //将流的初始化放到这里就不需要手动关闭流
                ByteArrayOutputStream baos = new ByteArrayOutputStream();
        ) {
            String code = generate(width, height, baos);
            verifyCode = new VerifyCode();
            verifyCode.setCode(code);
            verifyCode.setImgBytes(baos.toByteArray());
        } catch (IOException e) {
            logger.error(e.getMessage(), e);
            verifyCode = null;
        }
        return verifyCode;
    }

    /**
     * 设置字符颜色大小
     *
     * @param g
     * @param randomStr
     */
    private void createCharacter(Graphics g, String randomStr) {
        char[] charArray = randomStr.toCharArray();
        for (int i = 0; i < charArray.length; i++) {
            //设置RGB颜色算法参数
            g.setColor(new Color(50 + RandomUtils.nextInt(100),
                    50 + RandomUtils.nextInt(100), 50 + RandomUtils.nextInt(100)));
            //设置字体大小，类型
            g.setFont(new Font(FONT_TYPES[RandomUtils.nextInt(FONT_TYPES.length)], Font.BOLD, 26));
            //设置x y 坐标
            g.drawString(String.valueOf(charArray[i]), 15 * i + 5, 19 + RandomUtils.nextInt(8));
        }
    }
}

4.工具类

 package com.youyou.util;

import java.awt.*;
import java.util.Random;

public class RandomUtils extends org.apache.commons.lang3.RandomUtils {

    private static final char[] CODE_SEQ = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'J',
            'K', 'L', 'M', 'N', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W',
            'X', 'Y', 'Z', '2', '3', '4', '5', '6', '7', '8', '9' };

    private static final char[] NUMBER_ARRAY = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' };

    private static Random random = new Random();

    public static String randomString(int length) {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < length; i++) {
            sb.append(String.valueOf(CODE_SEQ[random.nextInt(CODE_SEQ.length)]));
        }
        return sb.toString();
    }

    public static String randomNumberString(int length) {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < length; i++) {
            sb.append(String.valueOf(NUMBER_ARRAY[random.nextInt(NUMBER_ARRAY.length)]));
        }
        return sb.toString();
    }

    public static Color randomColor(int fc, int bc) {
        int f = fc;
        int b = bc;
        Random random = new Random();
        if (f > 255) {
            f = 255;
        }
        if (b > 255) {
            b = 255;
        }
        return new Color(f + random.nextInt(b - f), f + random.nextInt(b - f), f + random.nextInt(b - f));
    }

    public static int nextInt(int bound) {
        return random.nextInt(bound);
    }
}

经过以上代码，我们的验证码生成功能基本上已经实现了，现在还需要一个controller来调用它。

     @ApiOperation(value = "验证码")
    @GetMapping("/verifyCode")
    public void verifyCode(HttpServletRequest request, HttpServletResponse response) {
        IVerifyCodeGen iVerifyCodeGen = new SimpleCharVerifyCodeGenImpl();
        try {
            //设置长宽
            VerifyCode verifyCode = iVerifyCodeGen.generate(80, 28);
            String code = verifyCode.getCode();
            LOGGER.info(code);
            //将VerifyCode绑定session
            request.getSession().setAttribute("VerifyCode", code);
            //设置响应头
            response.setHeader("Pragma", "no-cache");
            //设置响应头
            response.setHeader("Cache-Control", "no-cache");
            //在代理服务器端防止缓冲
            response.setDateHeader("Expires", 0);
            //设置响应内容类型
            response.setContentType("image/jpeg");
            response.getOutputStream().write(verifyCode.getImgBytes());
            response.getOutputStream().flush();
        } catch (IOException e) {
            LOGGER.info("", e);
        }
    }

搞定！后台编写到此结束了。那么又会有博友说了：“说好的实现效果呢？”

好吧，那么我们继续前端的代码编写。

前端代码:

 <html>
<body>

<div>
    <input id="code" placeholder="验证码" type="text" class=""
           style="width:170px">
    <!-- 验证码 显示 -->
    <img οnclick="javascript：getvCode()" id="verifyimg" style="margin-left: 20px;"/>
</div>

<script type="text/javascript">
    getvCode();

    /**
     * 获取验证码
     * 将验证码写到login.html页面的id = verifyimg 的地方
     */
    function getvCode() {
        document.getElementById("verifyimg").src = timestamp("http://127.0.0.1:81/verifyCode");
    }
    //为url添加时间戳
     function timestamp(url) {
        var getTimestamp = new Date().getTime();
        if (url.indexOf("?") > -1) {
            url = url + "×tamp=" + getTimestamp
        } else {
            url = url + "?timestamp=" + getTimestamp
        }
        return url;
    };


</script>
</body>

</html>

可以实现点击图片更换验证码。

实现效果：

​

当然文章开头的截图是我系统中的截图，需要大家自己去根据自己的情况去开发前端了。