015服务网关Zuul

常用的网关方案

• Nginx+Lua
• Kong
• Tyk Go语言开发的
• Spring Cloud Zuul

Zuul的特点

• 路由+过滤器=Zuul
• 核心是一系列的过滤器

Zuul的四种过滤器API

• 前置（Pre）
• 后置（Post）
• 路由（Route）
• 错误（Error）

使用Zuul实现网关

1.添加依赖

<dependency>
	<groupId>org.springframework.cloud</groupId>
	<artifactId>spring-cloud-starter-netflix-zuul</artifactId>
</dependency>

2.添加启动@EnableZuulProxy

@SpringBootApplication
@EnableZuulProxy
public class ApiGatewayApplication {

	public static void main(String[] args) {
		SpringApplication.run(ApiGatewayApplication.class, args);
	}
}

3.测试

• 原来

http://127.0.0.1:8082/product/list

• 代理后，第一个product是服务的名字

http://127.0.0.1:9000/product/product/list

4.自定义路由

• 配置文件

zuul:
  routes:
    myProduct:
      path: /myProduct/**
      serviceId: product

• 简洁写法

zuul:
  routes:
      product: /myProduct/**

• 测试：http://127.0.0.1:9000/myProduct/product/list

排除某些路由

zuul:
  routes:
    myProduct:
      product: /myProduct/**
  # 排除某些路由
  ignored-patterns:
    - /**/product/listForOrder

Zuul默认不传Cookie信息，需要传是需要配sensitiveHeaders未空才会传

zuul:
  routes:
    myProduct:
      path: /myProduct/**
      serviceId: product
      sensitiveHeaders: 

动态刷新配置

@Component
public class ZuulConfig {

    @ConfigurationProperties("zuul")
    @RefreshScope
    public ZuulProperties zuulProperties(){
        return new ZuulProperties();
    }
}

二、Zuul自定义过滤器

• 进入时过滤，如权限token读取

package com.matea.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.apache.http.HttpStatus;
import org.springframework.stereotype.Component;
import javax.servlet.http.HttpServletRequest;
import static org.springframework.cloud.netflix.zuul.filters.support.FilterConstants.*;

@Component
public class TokenFilter extends ZuulFilter{
    @Override
    public String filterType() {
        return PRE_TYPE;
    }

    @Override
    public int filterOrder() {
        return PRE_DECORATION_FILTER_ORDER -1;
    }

    @Override
    public boolean shouldFilter() {
        return true;
    }

    @Override
    public Object run() throws ZuulException {
        RequestContext requestContext = RequestContext.getCurrentContext();
        HttpServletRequest request = requestContext.getRequest();
        //这里从url参数里获取，也可以从cookie,header里获取
        String token = request.getParameter("token");
        if(StringUtils.isEmpty(token)){
            requestContext.setSendZuulResponse(false);
            requestContext.setResponseStatusCode(HttpStatus.SC_UNAUTHORIZED);
        }
        return null;
    }
}

• 返回时调用，如返回添加头信息

package com.matea.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.HttpServletResponse;
import java.util.UUID;
import static org.springframework.cloud.netflix.zuul.filters.support.FilterConstants.PRE_TYPE;
import static org.springframework.cloud.netflix.zuul.filters.support.FilterConstants.SEND_RESPONSE_FILTER_ORDER;

@Component
public class addResponseHeaderFilter  extends ZuulFilter {
    @Override
    public String filterType() {
        return PRE_TYPE;
    }

    @Override
    public int filterOrder() {
        return SEND_RESPONSE_FILTER_ORDER-1;
    }

    @Override
    public boolean shouldFilter() {
        return true;
    }

    @Override
    public Object run() throws ZuulException {
        RequestContext requestContext = RequestContext.getCurrentContext();
        HttpServletResponse response = requestContext.getResponse();
        response.setHeader("X-Foo", UUID.randomUUID().toString());
        return null;
    }
}

三、Zuul限流

• 缓存，限流和降级是系统的三把利剑，用谷歌RateLimiter 实现令牌桶限流
• 令牌桶算法的原理是：系统以恒定的速率往桶里丢一定数量的令牌，请求只有拿到了令牌才能处理。当桶里没有令牌时便可拒绝服务。

package com.matea.filter;

import com.google.common.util.concurrent.RateLimiter;
import com.matea.exception.RateLimitException;
import com.netflix.zuul.ZuulFilter;
import com.netflix.zuul.exception.ZuulException;
import static org.springframework.cloud.netflix.zuul.filters.support.FilterConstants.PRE_TYPE;
import static org.springframework.cloud.netflix.zuul.filters.support.FilterConstants.SERVLET_DETECTION_FILTER_ORDER;

public class RateLimitFilter extends ZuulFilter {

    private  static  final RateLimiter RATE_LIMITER =RateLimiter.create(100);

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

    @Override
    public int filterOrder() {
        return SERVLET_DETECTION_FILTER_ORDER-1;
    }

    @Override
    public boolean shouldFilter() {
        return true;
    }

    @Override
    public Object run() throws ZuulException {
        if(!RATE_LIMITER.tryAcquire()){
            throw  new RateLimitException();
        }
        return null;
    }
}

四、Zuul权限校验

• 网关全部服务忽略敏感头

zuul:
  # 全部服务忽略敏感头（全部服务都可以传递 Cookie）
  sensitive-headers: 

五、Zuul跨域

跨域问题处理方案

• 1.在被调用的类方法上增加@CrossOrigin注解

单个接口上添加
@GetMapping("/list")
@CrossOrigin(allowCredentials = "true")
public ResultVO<ProductVO> list() {}

@CrossOrigin(allowCredentials = "true")
allowCredentials = "true" 表示允许cookie跨域

• 2.在Zuul里面增加CrosFilter过滤器

package com.matea.config;

import org.apache.catalina.filters.CorsFilter;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.cors.CorsConfiguration;
import org.springframework.web.cors.UrlBasedCorsConfigurationSource;
import java.util.Arrays;

/**
 * 跨域配置
 */
@Configuration
public class CorsConfig {

    @Bean
    public CorsFilter corsFilter(){
        final UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
        final CorsConfiguration config = new CorsConfiguration();
        config.setAllowCredentials(true);
        config.setAllowedOrigins(Arrays.asList("*"));//默认 http:www.a.com
        config.setAllowedHeaders(Arrays.asList("*"));
        config.setAllowedMethods(Arrays.asList("*"));
        config.setMaxAge(300l);//换成时间
        source.registerCorsConfiguration("/**",config);
        return  new CorsFilter()
    }

}