Java实现图形验证码

实现类

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


public class ImageVerificationCode {
    /**
     * 验证码图片的长
     */
    private final int weight = 100;
    /**
     * 验证码图片的宽
     */
    private final int height = 40;
    /**
     * 获取随机数对象
     */
    private final Random r = new Random();
    /**
     * 字体数组 {"宋体", "华文楷体", "黑体", "微软雅黑", "楷体_GB2312"};
     */
    private final String[] fontNames = {"Georgia"};
    /**
     * 用来保存验证码的文本内容
     */
    private String text;

    /**
     * 将验证码图片写出的方法
     * @param image
     * @param out
     * @throws IOException
     */
    public static void output(BufferedImage image, OutputStream out) throws IOException {
        ImageIO.write(image, "JPEG", out);
    }

    /**
     * 获取随机的颜色
     *
     * @return
     */
    private Color randomColor() {
        //这里为什么是225，因为当r，g，b都为255时，即为白色，为了好辨认，需要颜色深一点。
        int r = this.r.nextInt(225);
        int g = this.r.nextInt(225);
        int b = this.r.nextInt(225);
        //返回一个随机颜色
        return new Color(r, g, b);
    }

    /**
     * 获取随机字体
     *
     * @return
     */
    private Font randomFont() {
        //获取随机的字体
        int index = r.nextInt(fontNames.length);
        String fontName = fontNames[index];
        //随机获取字体的样式，0是无样式，1是加粗，2是斜体，3是加粗加斜体
        int style = r.nextInt(4);
        //随机获取字体的大小
        int size = r.nextInt(10) + 24;
        //返回一个随机的字体
        return new Font(fontName, style, size);
    }

    /**
     * 获取随机字符
     *
     * @return
     */
    private char randomChar() {
        //验证码数组
        String codes = "23456789abcdefghjkmnopqrstuvwxyzABCDEFGHJKMNPQRSTUVWXYZ";
        int index = r.nextInt(codes.length());
        return codes.charAt(index);
    }

    /**
     * 画干扰线，验证码干扰线用来防止计算机解析图片
     *
     * @param image
     */
    private void drawLine(BufferedImage image) {
        //定义干扰线的数量
        int num = r.nextInt(10);
        Graphics2D g = (Graphics2D) image.getGraphics();
        for (int i = 0; i < num; i++) {
            int x1 = r.nextInt(weight);
            int y1 = r.nextInt(height);
            int x2 = r.nextInt(weight);
            int y2 = r.nextInt(height);
            g.setColor(randomColor());
            g.drawLine(x1, y1, x2, y2);
        }
    }

    /**
     * 创建图片的方法
     *
     * @return
     */
    private BufferedImage createImage() {
        //创建图片缓冲区
        BufferedImage image = new BufferedImage(weight, height, BufferedImage.TYPE_INT_RGB);
        //获取画笔
        Graphics2D g = (Graphics2D) image.getGraphics();
        //设置背景色随机
        g.setColor(new Color(255, 255, r.nextInt(245) + 10));
        g.fillRect(0, 0, weight, height);
        //返回一个图片
        return image;
    }

    /**
     * 获取验证码图片的方法
     *
     * @return
     */
    public BufferedImage getImage() {
        BufferedImage image = createImage();
        //获取画笔
        Graphics2D g = (Graphics2D) image.getGraphics();
        StringBuilder sb = new StringBuilder();
        //画四个字符即可
        for (int i = 0; i < 4; i++) {
            //随机生成字符，因为只有画字符串的方法，没有画字符的方法，所以需要将字符变成字符串再画
            String s = randomChar() + "";
            //添加到StringBuilder里面
            sb.append(s);
            //定义字符的x坐标
            float x = i * 1.0F * weight / 4;
            //设置字体，随机
            g.setFont(randomFont());
            //设置颜色，随机
            g.setColor(randomColor());
            g.drawString(s, x, height - 5);
        }
        this.text = sb.toString();
        drawLine(image);
        return image;
    }

    /**
     * 获取验证码文本的方法
     *
     * @return
     */
    public String getText() {
        return text;
    }
}

调用方法

    @ApiOperation("获取图片验证码")
    @GetMapping("/getPictureValidationCode")
    @ResponseBody
    @Override
    @ApiHeaderCheck
    public void getPictureValidationCode(HttpServletRequest request, HttpServletResponse response) throws IOException {
        //获取图形验证码
        ImageVerificationCode imageVerificationCode = new ImageVerificationCode();
        BufferedImage image = imageVerificationCode.getImage();
        //将验证码的文本存在session中
        request.getSession().setAttribute("validationCode", imageVerificationCode.getText());
        //将验证码图片响应给客户端
        ImageVerificationCode.output(image, response.getOutputStream());
    }

    @ApiOperation("校验图片验证码")
    @GetMapping("/checkPictureValidationCode")
    @ResponseBody
    @Override
    @ApiHeaderCheck
    public CommonResult<Boolean> checkPictureValidationCode(HttpServletRequest request, HttpServletResponse response, @RequestParam String validationCode) {
        String rightValidationCode = (String) request.getSession().getAttribute("validationCode");
        if (StringUtils.isEmpty(rightValidationCode) || !rightValidationCode.toLowerCase().equals(validationCode.toLowerCase())) {
            return CommonResult.<Boolean>builder().result(false).build();
        }
        //重置今日该ip请求验证码次数
        String ipAddress = IpAddressUtil.getIPAddress(request);
        Long zeroTimeWithTimeZone = DateUtils.getZeroTimeWithTimeZone(null);
        String key = ipAddress + "_VALIDATE_CODE_TIMES_" + zeroTimeWithTimeZone;
        redisUtil2.set(key, 0, DateUtils.SECOND_OF_DAY);
        return CommonResult.<Boolean>builder().result(true).build();
    }

前端获取

1.首先在http请求里，加上responseType: 'blob'，如：

然后：将返回的blob类型的图片转成base64

let blob = res.data;
let reader = new FileReader();
reader.readAsDataURL(blob); // 转换为base64
reader.onload = function () {
_this.url= reader.result