Spring Cloud（7）：Zuul自定義過濾器和接口限流

上文講到了Zuul的基本使用：

http://www.javashuo.com/article/p-bvipxwmc-du.html

 

自定義Zuul過濾器：

package org.dreamtech.apigateway.filter;

import com.netflix.zuul.ZuulFilter;
import com.netflix.zuul.context.RequestContext;
import com.netflix.zuul.exception.ZuulException;
import org.springframework.stereotype.Component;

import javax.servlet.http.HttpServletRequest;

import static org.springframework.cloud.netflix.zuul.filters.support.FilterConstants.PRE_TYPE;

/**
 * 登錄過濾器
 */
@Component
public class LoginFilter extends ZuulFilter {

    /**
     * 設置過濾器類型
     *
     * @return String
     */
    @Override
    public String filterType() {
        //設置爲前置過濾器
        return PRE_TYPE;
    }

    /**
     * 過濾器順序：值越小，越先執行
     *
     * @return int
     */
    @Override
    public int filterOrder() {
        //不能是最早執行的
        return 4;
    }

    /**
     * 過濾是否生效
     *
     * @return boolean
     */
    @Override
    public boolean shouldFilter() {
        RequestContext requestContext = RequestContext.getCurrentContext();
        HttpServletRequest request = requestContext.getRequest();
        return "/order/api/order/save".equalsIgnoreCase(request.getRequestURI());
    }

    /**
     * shouldFilter返回True則執行此方法，用於寫業務邏輯
     *
     * @return Object
     * @throws ZuulException 異常
     */
    @Override
    public Object run() throws ZuulException {
        System.out.println("攔截成功");
        return null;
    }
}

啓動項目：Eureka Server->Product-Service->Order-Service->Api Gateway

 

這裏對模擬的下單接口進行了過濾

訪問：http://localhost:9000/order/api/order/save?user_id=1&product_id=1

就會打印：攔截成功

 

進一步編碼：

package org.dreamtech.apigateway.filter;

import com.netflix.zuul.ZuulFilter;
import com.netflix.zuul.context.RequestContext;
import com.netflix.zuul.exception.ZuulException;
import org.apache.commons.lang.StringUtils;
import org.springframework.http.HttpStatus;
import org.springframework.stereotype.Component;

import javax.servlet.http.HttpServletRequest;

import static org.springframework.cloud.netflix.zuul.filters.support.FilterConstants.PRE_TYPE;

/**
 * 登錄過濾器
 */
@Component
public class LoginFilter extends ZuulFilter {

    /**
     * 設置過濾器類型
     *
     * @return String
     */
    @Override
    public String filterType() {
        //設置爲前置過濾器
        return PRE_TYPE;
    }

    /**
     * 過濾器順序：值越小，越先執行
     *
     * @return int
     */
    @Override
    public int filterOrder() {
        //不能是最早執行的
        return 4;
    }

    /**
     * 過濾是否生效
     *
     * @return boolean
     */
    @Override
    public boolean shouldFilter() {
        RequestContext requestContext = RequestContext.getCurrentContext();
        HttpServletRequest request = requestContext.getRequest();
        return "/order/api/order/save".equalsIgnoreCase(request.getRequestURI());
    }

    /**
     * 寫業務邏輯
     *
     * @return Object
     * @throws ZuulException 異常
     */
    @Override
    public Object run() throws ZuulException {
        RequestContext requestContext = RequestContext.getCurrentContext();
        HttpServletRequest request = requestContext.getRequest();

        String token = request.getHeader("token");

        if (StringUtils.isBlank(token)) {
            token = request.getParameter("token");
        }
        //登錄校驗邏輯
        if (StringUtils.isBlank(token)) {
            requestContext.setSendZuulResponse(false);
            requestContext.setResponseStatusCode(HttpStatus.UNAUTHORIZED.value());
        }
        return null;
    }
}

實際中，可使用一種技術：JWT來作安全校驗

 

這時候直接訪問：http://localhost:9000/order/api/order/save?user_id=1&product_id=1

顯示：401狀態碼（未受權）

 

訪問：http://localhost:9000/order/api/order/save?user_id=1&product_id=1&token=12345

顯示：

{"code":0,"data":{"id":0,"productName":"\"iPhone1 data from port=8771\"","tradeNo":"29d834be-f375-4112-b0a1-ed10b8e8679d","price":1111,"createTime":"2019-05-19T04:26:19.008+0000","userId":1,"userName":null}}

成功

 

爲了方便，我直接把token放在參數裏面了，根據編碼也能夠把token放在HttpHeader裏面

進一步的編碼能夠這樣嘗試：

    @Override
    public boolean shouldFilter() {
        RequestContext requestContext = RequestContext.getCurrentContext();
        HttpServletRequest request = requestContext.getRequest();
        //TODO 從Resdis緩存中拿到List<[URL]>代替"/order/api/order/save"
        if ("/order/api/order/save".equalsIgnoreCase(request.getRequestURI())) {
            return true;
        }
        if ("/order/api/order/delete".equalsIgnoreCase(request.getRequestURI())) {
            return true;
        }
        // ......
        return false;
    }

 

高併發的狀況下，接口限流是頗有必要的：

相似地鐵：上地鐵須要排隊，才能夠有效地運輸；若是一羣人擁擠，反而效率不高

實際應用：好比某電商網站搞活動，某一時刻同時訪問上萬人，而MySQL最大鏈接數3000，這時候就要進行限制：最高只能由2500人同時參與活動

限流的方式：Nginx進行限流、網關限流等。這裏進行網關限流

使用Google Guava框架：令牌桶原理

Demo：對訂單服務進行限流

package org.dreamtech.apigateway.filter;

import com.google.common.util.concurrent.RateLimiter;
import com.netflix.zuul.ZuulFilter;
import com.netflix.zuul.context.RequestContext;
import com.netflix.zuul.exception.ZuulException;
import org.springframework.http.HttpStatus;
import org.springframework.stereotype.Component;

import javax.servlet.http.HttpServletRequest;

import static org.springframework.cloud.netflix.zuul.filters.support.FilterConstants.PRE_TYPE;

@Component
public class OrderLimiterFilter extends ZuulFilter {

    //每秒建立1000個令牌
    private static final RateLimiter RATE_LIMITER = RateLimiter.create(1000);

    @Override
    public String filterType() {
        return PRE_TYPE;
    }

    @Override
    public int filterOrder() {
        //最早執行
        return -4;
    }

    @Override
    public boolean shouldFilter() {
        RequestContext requestContext = RequestContext.getCurrentContext();
        HttpServletRequest request = requestContext.getRequest();
        //對訂單接口進行限流
        return "/order/api/order/save".equalsIgnoreCase(request.getRequestURI());
    }

    @Override
    public Object run() throws ZuulException {
        RequestContext requestContext = RequestContext.getCurrentContext();
        //非阻塞式獲取令牌
        if (!RATE_LIMITER.tryAcquire()) {
            requestContext.setSendZuulResponse(false);
            requestContext.setResponseStatusCode(HttpStatus.TOO_MANY_REQUESTS.value());
        }
        return null;
    }
}

 

實際開發中，不僅是要保證數據庫和服務的高可用，也要保證網關不會掛掉：

Nginx能夠和LVS組合實現高可用，不過這是運維要作的事情，咱們Java程序員須要關心的是Zuul的高可用

因而想到部署Zuul集羣：Zuul的集羣搭建很簡單，啓動多個Zuul項目便可

 

可能有人會關心，若是Zuul是集羣的方式，那麼Guava的令牌桶如何實現共用？

後面會介紹Spring Cloud統一配置Config進行處理