maven依赖

<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.3.RELEASE</version>
        <relativePath />
    </parent>
    <properties>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
        <springboot.version>2.1.3.RELEASE</springboot.version>
    </properties>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-freemarker</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>kaptcha-spring-boot-starter</artifactId>
            <version>1.0.0</version>
        </dependency>

KaptchaConfig配置

@Configuration
public class KaptchaConfig { 
    @Bean
    public Kaptcha Kaptcha() { 
        return new GoogleKaptcha(defaultKaptcha());
    }
    @Bean
    public DefaultKaptcha defaultKaptcha() { 
        DefaultKaptcha defaultKaptcha = new DefaultKaptcha();
        Properties properties = new Properties();
        properties.setProperty("kaptcha.border", "yes");
        properties.setProperty("kaptcha.border.color", "105,179,90");
        properties.setProperty("kaptcha.textproducer.font.color", "blue");
        properties.setProperty("kaptcha.image.width", "125");
        properties.setProperty("kaptcha.image.height", "45");
        properties.setProperty("kaptcha.session.key", "code");
        properties.setProperty("kaptcha.textproducer.char.length", "4");
        properties.setProperty("kaptcha.textproducer.font.names", "宋体,楷体,微软雅黑");
        Config config = new Config(properties);
        defaultKaptcha.setConfig(config);
        return defaultKaptcha;
    }
}
@RestController
@RequestMapping("/kaptcha")
public class KaptchaController { 
    @Autowired
    private Kaptcha kaptcha;
    @GetMapping("/render")
    Object render() { 
        String render = kaptcha.render();
        System.err.println("render=" + render);
        return render;
    }
    @GetMapping("/valid")
    Object validDefaultTime(@RequestParam String code) { 
        boolean validate = kaptcha.validate(code);
        System.err.println("validate=" + validate);
        return validate;
    }
    @GetMapping("/validTime")
    Object validWithTime(@RequestParam String code) { 
        boolean validate = kaptcha.validate(code, 60);
        System.err.println("validate=" + validate);
        return validate;
    }
}