Spring Cloud（7）：Zuul自定义过滤器和接口限流

2019-05-22 06:28:29来源：博客园阅读 ()

上文讲到了Zuul的基本使用：

https://www.cnblogs.com/xuyiqing/p/10884860.html

自定义Zuul过滤器：

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;

/**
 * 登陆过滤器
 */
@Component
public class LoginFilter extends ZuulFilter {

    /**
     * 设置过滤器类型
     *
     * @return String
     */
    @Override
    public String filterType() {
        //设置为前置过滤器
        return PRE_TYPE;
    }

    /**
     * 过滤器顺序：值越小，越先执行
     *
     * @return int
     */
    @Override
    public int filterOrder() {
        //不能是最先执行的
        return 4;
    }

    /**
     * 过滤是否生效
     *
     * @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则执行此方法，用于写业务逻辑
     *
     * @return Object
     * @throws ZuulException 异常
     */
    @Override
    public Object run() throws ZuulException {
        System.out.println("拦截成功");
        return null;
    }
}

启动项目：Eureka Server->Product-Service->Order-Service->Api Gateway

这里对模拟的下单接口进行了过滤

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

就会打印：拦截成功

进一步编码：

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;

/**
 * 登陆过滤器
 */
@Component
public class LoginFilter extends ZuulFilter {

    /**
     * 设置过滤器类型
     *
     * @return String
     */
    @Override
    public String filterType() {
        //设置为前置过滤器
        return PRE_TYPE;
    }

    /**
     * 过滤器顺序：值越小，越先执行
     *
     * @return int
     */
    @Override
    public int filterOrder() {
        //不能是最先执行的
        return 4;
    }

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

    /**
     * 写业务逻辑
     *
     * @return Object
     * @throws ZuulException 异常
     */
    @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");
        }
        //登陆校验逻辑
        if (StringUtils.isBlank(token)) {
            requestContext.setSendZuulResponse(false);
            requestContext.setResponseStatusCode(HttpStatus.UNAUTHORIZED.value());
        }
        return null;
    }
}

实际中，可以使用一种技术：JWT来做安全校验

这时候直接访问：http://localhost:9000/order/api/order/save?user_id=1&product_id=1

显示：401状态码（未授权）

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

显示：

{"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

为了方便，我直接把token放在参数里面了，根据编码也可以把token放在HttpHeader里面

进一步的编码可以这样尝试：

    @Override
    public boolean shouldFilter() {
        RequestContext requestContext = RequestContext.getCurrentContext();
        HttpServletRequest request = requestContext.getRequest();
        //TODO 从Resdis缓存中拿到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;
    }

高并发的情况下，接口限流是很有必要的：

类似地铁：上地铁需要排队，才可以有效地运输；如果一群人拥挤，反而效率不高

实际应用：比如某电商网站搞活动，某一时刻同时访问上万人，而MySQL最大连接数3000，这时候就要进行限制：最高只能由2500人同时参与活动

限流的方式：Nginx进行限流、网关限流等。这里进行网关限流

使用Google Guava框架：令牌桶原理

Demo：对订单服务进行限流

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 {

    //每秒创建1000个令牌
    private static final RateLimiter RATE_LIMITER = RateLimiter.create(1000);

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

    @Override
    public int filterOrder() {
        //最先执行
        return -4;
    }

    @Override
    public boolean shouldFilter() {
        RequestContext requestContext = RequestContext.getCurrentContext();
        HttpServletRequest request = requestContext.getRequest();
        //对订单接口进行限流
        return "/order/api/order/save".equalsIgnoreCase(request.getRequestURI());
    }

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