Spring中整合Cage，实现验证码功能

1.pom.xml中添加Cage依赖。

    <dependency>
            <groupId>com.github.cage</groupId>
            <artifactId>cage</artifactId>
            <version>1.0</version>
        </dependency>    

项目相关资料：https://akiraly.github.io/cage/quickstart.html 。

2.Controller：@RestController

@RestController
@RequestMapping("captcha")
public class CaptchaController {

    @Autowired
    private CaptchaService captchaService;

    @RequestMapping("get")
    public void get(HttpServletResponse response,String key) throws IOException {
        response.setContentType("image/jpeg");//设置响应的媒体类型，这样浏览器会识别出响应的是图片
        response.getOutputStream().write(captchaService.getCaptcha(key));
        response.flushBuffer();
    }
}

3.Service：

@Service("captchaService")
public class CaptchaService {

    private static final Logger log = LoggerFactory.getLogger(CaptchaService.class);

    @Autowired
    RedisDao redisDao;
    Cage cage = new GCage();

    public byte[] getCaptcha(String id) {
        if (StringUtils.isBlank(id)) {
            return null;
        }
        ByteArrayOutputStream os = new ByteArrayOutputStream();
        String token = cage.getTokenGenerator().next().substring(0, 4);
        try {
            cage.draw(token, os);
            os.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
        String key = "captcha-" + id;
        redisDao.getJredis().opsForValue().set(key, token);
        redisDao.getJredis().expire(key, 1, TimeUnit.HOURS);
        return os.toByteArray();
    }

    public boolean matchCaptcha(String id, String captcha) {
        if (StringUtils.isBlank(id) || StringUtils.isBlank(captcha)) {
            return false;
        }
        String key = "captcha-" + id;
        String redisCaptcha = String.valueOf(redisDao.getJredis().opsForValue().get(key));
        if (StringUtils.isBlank(redisCaptcha)) {
            return false;
        }
        log.info(id + ", " + captcha + ", " + redisCaptcha);
        return StringUtils.equalsIgnoreCase(captcha, redisCaptcha);
    }
}

4.前端页面：

$('#yzmimg').attr('src','https://localhost:8082/captcha/get?key'+timestamp);

总结：设置

response.setContentType("image/jpeg")，这样返回时将会以图片形式，此处为坑。