通过过滤器实现简单的限流操作

1@Component
2@Slf4j
3public class MyFilter implements Filter {
4
5
6  private static volatile long startTime = System.currentTimeMillis();
7
8  // 时间窗口
9  private static final long windowTime = 1000L;
10
11  // 1s只能通过200个请求
12  private static final int door = 200;
13
14  private static final AtomicInteger bear = new AtomicInteger(0);
15
16  @Override
17  public void init(FilterConfig filterConfig) throws ServletException {
18    Filter.super.init(filterConfig);
19  }
20
21  @Override
22  public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
23    int count = bear.incrementAndGet();
24    if (count == 1) {
25      startTime = System.currentTimeMillis();
26    }
27    long now = System.currentTimeMillis();
28    log.info("拦截了请求， count： {}", count);
29    log.info("时间窗口: {}ms, count: {}", (now - startTime), count);
30    if (now - startTime <= windowTime) {
31      if (count > door) {  // 超过了阈值
32        //   限流操作
33        log.info("限流， 拦截了请求, count: {}", count);
34        HttpServletResponse response = (HttpServletResponse) servletResponse;
35        response.setStatus(HttpStatus.OK.value());
36        response.setContentType(MediaType.APPLICATION_JSON_VALUE);
37        response.setCharacterEncoding(StandardCharsets.UTF_8.toString());
38        response.getWriter().print(JSONUtil.toJsonStr(Result.error("402", "接口请求过于频繁")));
39        return;
40      }
41    } else {
42      startTime = System.currentTimeMillis();
43      bear.set(1);
44    }
45    HttpServletRequest request = (HttpServletRequest) servletRequest;
46    filterChain.doFilter(servletRequest, servletResponse);
47    log.info("接口请求的路径：{}", request.getServletPath());
48  }
49
50  @Override
51  public void destroy() {
52    Filter.super.destroy();
53  }
54
55}