验证码

引入依赖

        <dependency>
            <groupId>cn.hutool</groupId>
            <artifactId>hutool-all</artifactId>
        </dependency>

编码实现

import cn.hutool.captcha.LineCaptcha;
import cn.hutool.core.img.ImgUtil;
import cn.hutool.core.util.RandomUtil;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.util.concurrent.ThreadLocalRandom;

public class SimpleCaptcha extends LineCaptcha{
	
	private static final long serialVersionUID = -9042552338521307038L;
	
	private static final String CAPTCHA_CODE = "abcdefhjkmnpqrstuvwxyz2345678";

	private final int codeCount;

	public SimpleCaptcha(int width, int height, int codeCount, int interfereCount) {
		super(width, height, codeCount, interfereCount);
		this.codeCount = codeCount;
	}

	@Override
	protected void generateCode() {
		this.code = RandomUtil.randomString(CAPTCHA_CODE,codeCount);
	}

	@Override
	public Image createImage(String code) {
		// 图像buffer
		final BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
		final ThreadLocalRandom random = RandomUtil.getRandom();
		final Graphics2D g = ImgUtil.createGraphics(image, new Color(249,249,249));
		// 干扰线
		drawInterfere(g, random);
		// 创建字体
		g.setFont(this.font);
		final FontMetrics metrics = g.getFontMetrics();
		int minY = metrics.getAscent() - metrics.getLeading() - metrics.getDescent();
		// 文字
		final int len = codeCount;
		int charWidth = width / len;
		for (int i = 0; i < len; i++) {
			// 产生随机的颜色值，让输出的每个字符的颜色值都将不同。
			g.setColor(ImgUtil.randomColor(random));
			g.setFont(new Font("Arial", Font.PLAIN, random.nextInt(20)+30));
			g.drawString(String.valueOf(code.charAt(i)), i * charWidth, RandomUtil.randomInt(minY, this.height));
		}
		return image;
	}

	/**
	 * 绘制干扰线
	 *
	 * @param g {@link Graphics2D}画笔
	 * @param random 随机对象
	 */
	private void drawInterfere(Graphics2D g, ThreadLocalRandom random) {
		// 干扰线
		for (int i = 0; i < this.interfereCount; i++) {
			int xs = random.nextInt(width);
			int ys = random.nextInt(height);
			int xe = xs + random.nextInt(width / (random.nextInt(8)+1));
			int ye = ys + random.nextInt(height / (random.nextInt(8)+1));
			g.setColor(ImgUtil.randomColor(random));
			g.drawLine(xs, ys, xe, ye);
		}
	}


	public static void main(String[] args) {
		SimpleCaptcha simpleCaptcha = new SimpleCaptcha(104, 50, 4, 50);
		simpleCaptcha.write("D:\\work\\123.jpg");
	}

}

控制器访问

    @GetMapping("/captcha.jpg")
    public Object login(HttpServletRequest request,@RequestParam(required = false, defaultValue = "false") String value
                        ,@RequestParam(required = false, defaultValue = "104") int width,@RequestParam(required = false, defaultValue = "50") int height) {

        //定义图形验证码的长、宽、验证码字符数、干扰元素个数
        SimpleCaptcha simpleCaptcha = new SimpleCaptcha(width, height, 4, 30);
        if (value.equals("true")) {
            ConcurrentHashMapCacheUtils.setCache("captcha_jpg" + request.getRemoteAddr(), simpleCaptcha.getCode(), 1000*60*5);
            return ResponseUtil.ok(simpleCaptcha.getCode());
        }
        try(ByteArrayOutputStream stream = new ByteArrayOutputStream()) {
            simpleCaptcha.write(stream);
            String base64 = Base64.encode(stream.toByteArray());
            ConcurrentHashMapCacheUtils.setCache("captcha_jpg" + request.getRemoteAddr(), simpleCaptcha.getCode(), 1000*60*5);
            return ResponseUtil.ok(base64);
        } catch (IOException e) {
            e.printStackTrace();
        }
        return ResponseUtil.fail();
    }