guava RateLimiter 使用笔记

使用guava包中的RateLimiter限制每个IP接口请求速率，添加如下filter

package com.caiyi.financial.nirvana.loan.filter;

import com.google.common.util.concurrent.RateLimiter;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

/**
 * Created by liu
 */
@WebFilter
public class RateLimiterFilter implements Filter {
    private static Logger logger = LoggerFactory.getLogger(PrivilegeFilter.class);

    /**
     * The Limiter map.
     */
    static Map<String, RateLimiter> limiterMap = new ConcurrentHashMap<>();

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        HttpServletRequest httpServletRequest = (HttpServletRequest) request;
        //IP限制
        String ip = getRemoteHost(httpServletRequest);
        RateLimiter limiterIp = limiterMap.get(ip);
        if (limiterIp == null) {
            limiterIp = RateLimiter.create(16.0); // 每秒不超过16个请求被提交
            limiterMap.put(ip, limiterIp);
            logger.debug("IP个数：{}", limiterMap.size());
        } else {
            limiterWithReturn(limiterIp, httpServletRequest, response);
        }
    }

    @Override
    public void destroy() {

    }

    /**
     * 方法一：请求RateLimiter, 超过permits会被阻塞
     */
    @SuppressWarnings("useless")
    private void limiterWithBlock(RateLimiter limiter, ServletRequest requestWrapper, ServletResponse servletResponse) {
        logger.info("实际接口访问频率：{}次/秒", limiter.acquire());
    }

    /**
     * 方法二：请求RateLimiter, 超过permits直接返回
     */
    private void limiterWithReturn(RateLimiter limiter, HttpServletRequest request, ServletResponse servletResponse) throws IOException, ServletException {
        if (!limiter.tryAcquire()) {
            logger.warn("接口超频：{}，rate:{}，ip地址：{}",
                    request.getRequestURI(), limiter.getRate(), getRemoteHost(request));
            request.getRequestDispatcher("/error").forward(request, servletResponse);
        }
    }

    /**
     * Gets remote host.
     *
     * @param request the request
     * @return the remote host
     */
    public static String getRemoteHost(HttpServletRequest request) {
        String ip = request.getHeader("x-forwarded-for");
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
            ip = request.getHeader("Proxy-Client-IP");
        }
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
            ip = request.getHeader("WL-Proxy-Client-IP");
        }
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
            ip = request.getRemoteAddr();
        }
        return ip.equals("0:0:0:0:0:0:0:1") ? "127.0.0.1" : ip;
    }
}