import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface LimitAccess {

    /**
     * 限制訪問(wèn)的key
     * @return
     */
    String key();

    /**
     * 限制訪問(wèn)時(shí)間
     * @return
     */
    int times();
}

import com.example.demo.anno.LimitAccess;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.Signature;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;
import org.aspectj.lang.reflect.MethodSignature;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.stereotype.Component;
import java.util.concurrent.TimeUnit;

/**
 * AOP類（通知類）
 */
@Component
@Aspect
public class LimitAspect {

    @Autowired
    private RedisTemplate redisTemplate;

    @Pointcut("@annotation(com.example.demo.anno.LimitAccess)")
    public void pt(){};

    @Around("pt()")
    public Object aopAround(ProceedingJoinPoint pjp) throws Throwable {
        // 獲取切入點(diǎn)上面的自定義注解
        Signature signature = pjp.getSignature();
        MethodSignature methodSignature = (MethodSignature) signature;
        // 獲取方法上面的注解
        LimitAccess limitAccess = methodSignature.getMethod().getAnnotation(LimitAccess.class);
        // 獲取注解上面的屬性
        int limit = limitAccess.times();
        String key = limitAccess.key();
        // 根據(jù)key去找Redis中的值
        Object o = redisTemplate.opsForValue().get(key);
        // 如果不存在，說(shuō)明是首次訪問(wèn)，存入Redis，過(guò)期時(shí)間為limitAccess中的time
        if (o == null) {
            redisTemplate.opsForValue().set(key, "", limit, TimeUnit.SECONDS);
            // 執(zhí)行切入點(diǎn)的方法
            return pjp.proceed();
        } else {
            // 如果存在，說(shuō)明不是首次訪問(wèn)，給出提示信息
            return  "訪問(wèn)過(guò)于頻繁";
        }
    }
}

    @GetMapping("/download")
    @LimitAccess(key = "download_key", times = 20)
    public String downLoadFile(HttpServletRequest request, HttpServletResponse response) {
        FileInputStream inputStream = null;
        BufferedInputStream bufferedInputStream = null;
        OutputStream outputStream = null;
        try {
            File file = ResourceUtils.getFile("classpath:template/show.txt");
            if (file.exists()) {
                String fileName = file.getName();
                String mineType = request.getServletContext().getMimeType(fileName);
                response.setContentType(mineType);
                response.setHeader("content-type", "application/form-data");
                response.setHeader("Content-disposition", "attachment; fileName=" + fileName);
                inputStream = new FileInputStream(file);
                bufferedInputStream = new BufferedInputStream(inputStream);
                outputStream = response.getOutputStream();
                int len = 0;
                byte[] buff = new byte[1024];
                while ((len = bufferedInputStream.read(buff)) != -1) {
                    outputStream.write(buff, 0, len);
                }

            } else {
                return "下載的文件資源不存在";
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (inputStream != null) {
                    try {
                        inputStream.close();
                    } catch (IOException e) {
                        throw new RuntimeException(e);
                    }
                }
                if (bufferedInputStream != null) {
                    bufferedInputStream.close();
                }
                if (outputStream != null) {
                    outputStream.flush();
                    outputStream.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return "success";
    }