依赖

<!-- easy-captcha用来生成验证码，由于jdk9以后，内置JavaScript去掉了，所以需要导入这个org.openjdk.nashorn -->
<dependency><groupId>com.github.whvcse</groupId><artifactId>easy-captcha</artifactId><version>${easy-captcha.version}</version>
</dependency>
<dependency><groupId>org.openjdk.nashorn</groupId><artifactId>nashorn-core</artifactId><version>${nashorn-core.version}</version>
</dependency>

工具类

/*** 验证码工具类** @author hc*/
public class CaptchaUtil {/*** 默认字体大小*/private static Integer fontSize = 45;private static List<Font> list = new ArrayList<>();static {//静态代码快初始化，下面字体之所以注释掉是因为不好区分try {list.add(Font.createFont(Font.TRUETYPE_FONT, Objects.requireNonNull(Captcha.class.getResourceAsStream("/actionj.ttf"))));list.add(Font.createFont(Font.TRUETYPE_FONT, Objects.requireNonNull(Captcha.class.getResourceAsStream("/epilog.ttf"))));// list.add(Font.createFont(Font.TRUETYPE_FONT, Objects.requireNonNull(Captcha.class.getResourceAsStream("/fresnel.ttf"))));
//            list.add(Font.createFont(Font.TRUETYPE_FONT, Objects.requireNonNull(Captcha.class.getResourceAsStream("/headache.ttf"))));
//            list.add(Font.createFont(Font.TRUETYPE_FONT, Objects.requireNonNull(Captcha.class.getResourceAsStream("/lexo.ttf"))));list.add(Font.createFont(Font.TRUETYPE_FONT, Objects.requireNonNull(Captcha.class.getResourceAsStream("/prefix.ttf"))));list.add(Font.createFont(Font.TRUETYPE_FONT, Objects.requireNonNull(Captcha.class.getResourceAsStream("/progbot.ttf"))));
//            list.add(Font.createFont(Font.TRUETYPE_FONT, Objects.requireNonNull(Captcha.class.getResourceAsStream("/ransom.ttf"))));list.add(Font.createFont(Font.TRUETYPE_FONT, Objects.requireNonNull(Captcha.class.getResourceAsStream("/robot.ttf"))));
//            list.add(Font.createFont(Font.TRUETYPE_FONT, Objects.requireNonNull(Captcha.class.getResourceAsStream("/scandal.ttf"))));} catch (FontFormatException | IOException e) {e.printStackTrace();}}/*** @param type   验证码图片的类型* @param width* @param height* @param length* @return*/public static Captcha getCaptcha(int type, int width, int height, int length) {Captcha captcha;switch (type) {case 1:// 算术类型,固定设置为两位，图片为算数运算表达式captcha = new ArithmeticCaptcha(width, height, length);break;case 2://中文captcha = new ChineseCaptcha(width, height, length);break;case 3://中文gifcaptcha = new ChineseGifCaptcha(width, height, length);break;case 4://gif英文captcha = new GifCaptcha(width, height, length);break;case 5: //默认captcha = new SpecCaptcha(width, height, length);break;default:throw new RuntimeException("验证码配置信息错误");}//也可以不设置字体，直接使用系统默认的字体// 随机字体final int index = (int) (Math.random() * list.size());
//        System.out.println("index  " + index);captcha.setFont(list.get(index).deriveFont(Font.BOLD, fontSize));return captcha;}}

控制器

@RestController
@RequestMapping("/captcha")
public class CaptchaController {@GetMapping("/v1/get")public ResultBean<String> getCaptcha() {//生成验证码final Captcha captcha = CaptchaUtil.getCaptcha(1, 160, 55, 2);//验证码对应的文本System.out.println("验证码对应的文本: "+captcha.text());return captcha.toBase64();}}

效果