SpringBoot项目架构实战之“网关zuul搭建“

第三章网关zuul搭建

前言：

1、主要功能

zuul主要提供动态路由（内置ribbon实现）和过滤（可以做统一鉴权过滤器、灰度发布过滤器、黑白名单IP过滤器、服务限流过滤器（可以配合Sentinel实现））功能；

2、和Spring Cloud GateWay的区别

属于两个不同开源组织提供的网关解决方案。spring cloud GateWay使用非阻塞API，内置限流过滤器，支持长连接（比如 websockets），在高并发和后端服务响应慢的场景下比Zuul1的表现要好；zuul无内置限流过滤器，但是可以与Sentinel（是阿里开源的一款高性能的限流框架）集成使用。

一、创建zuul服务module

参考第二章eureka的创建

二、配置文件

1、pom文件配置

<?xml version="1.0"?>
<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <modelVersion>4.0.0</modelVersion>
  <parent>
    <groupId>com.hq</groupId>
    <artifactId>taxi-online</artifactId>
    <version>0.0.1-SNAPSHOT</version>
  </parent>
  
  <artifactId>taxi-online-zuul</artifactId>
  <name>taxi-online-zuul</name>
  <description>personal test for zuul</description>
  <url>org.apache</url>
  
  <packaging>jar</packaging>
  
  <dependencies>
  	<!-- zuul -->
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-netflix-zuul</artifactId>
    </dependency>
    <!-- eureka-client -->
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
    </dependency>
  </dependencies>
</project>

2、application.yml文件配置

#服务端口
server:
  port: 9100
#服务名  
spring:
  application:
    name: taxi-online-zuul
#服务注册    
eureka:
  client:
    service-url:
      defaultZone: http://localhost:9001/eureka/,http://localhost:9002/eureka/
    enabled: true # 是否启用Eureka client
  instance:
    hostname: localhost
    instance-id: taxi-online-zuul # 实例id

3、启动类

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.netflix.zuul.EnableZuulProxy;

@SpringBootApplication
@EnableZuulProxy
@EnableEurekaClient
public class StartSpringCloudZuul {
    public static void main(String[] args) {
        SpringApplication.run(StartSpringCloudZuul.class,args);
    }
}

三、zuul功能

1、动态路由

2、统一鉴权

3、过滤器

4、灰度发布

5、限流

四、底层源码

1、启动原理

类似注册中心：

1）boot启动类

boot启动类上添加@EnableZuulProxy注解；

2）EnableZuulProxy注解

EnableZuulProxy注解中导入ZuulProxyMarkerConfiguration配置类

@EnableCircuitBreaker
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Import(ZuulProxyMarkerConfiguration.class)
public @interface EnableZuulProxy {

}

3）ZuulProxyMarkerConfiguration配置类

ZuulProxyMarkerConfiguration配置类往容器添加了一个空的Marker对象，这个对象是作为容器是否添加ZuulProxyAutoConfiguration类的条件，因为ZuulProxyAutoConfiguration类上面加了@ConditionalOnBean(ZuulProxyMarkerConfiguration.Marker.class)的注解

@Configuration(proxyBeanMethods = false)
public class ZuulProxyMarkerConfiguration {

	@Bean
	public Marker zuulProxyMarkerBean() {
		return new Marker();
	}

	class Marker {

	}

}

4）spring.factories文件

zuul包下面的spring.factories文件指定了两个引入类，只要导包就会被引进去（由SpringFactoriesLoader 进行读取）--见下方截图。如果没有这个文件，boot的自动扫描不会扫描这些外部包的类。这两个引入类被注入容器的条件分别是:

@ConditionalOnBean(ZuulServerMarkerConfiguration.Marker.class)

@ConditionalOnBean(ZuulProxyMarkerConfiguration.Marker.class)

，分别可以通过在启动类上添加下面注解来引入相应的Marker类：

@EnableZuulProxy

@EnableZuulServer。

@EnableZuulServer、@EnableZuulProxy两个注解的区别：
@EnableZuulServer - 普通Zuul Server,只支持基本的route与filter功能.
@EnableZuulProxy - 普通Zuul Server+服务发现与熔断等功能的增强版,具有反向代理功能。
@EnableZuulProxy简单理解为@EnableZuulServer的增强版，当Zuul与Eureka、Ribbon等组件配合使用时，我们使用@EnableZuulProxy。所以我们做SpringCloud微服务系统一般都是使用@EnableZuulProxy。

5）ZuulServerAutoConfiguration配置类

ZuulServerAutoConfiguration配置类（源码见下方）主要做的事情有：

1、往容器注入了ZuulServlet，该类是zuul的核心类。

2、往容器注入了一些前置过滤器和后置过滤器。

3、注入ZuulFilterInitializer类并初始化，初始化逻辑中将所有过滤器交给FilterRegistry类进行管理。FilterRegistry类源码如下：

/**
 * @author mhawthorne
 */
public class FilterRegistry {

    private static final FilterRegistry INSTANCE = new FilterRegistry();

    public static final FilterRegistry instance() {
        return INSTANCE;
    }

    private final ConcurrentHashMap<String, ZuulFilter> filters = new ConcurrentHashMap<String, ZuulFilter>();

    private FilterRegistry() {
    }

    public ZuulFilter remove(String key) {
        return this.filters.remove(key);
    }

    public ZuulFilter get(String key) {
        return this.filters.get(key);
    }

    public void put(String key, ZuulFilter filter) {
        this.filters.putIfAbsent(key, filter);
    }

    public int size() {
        return this.filters.size();
    }

    public Collection<ZuulFilter> getAllFilters() {
        return this.filters.values();
    }

}

ZuulServerAutoConfiguration源码如下（有删减）：

/**
 * @author Spencer Gibb
 * @author Dave Syer
 * @author Biju Kunjummen
 */
@Configuration(proxyBeanMethods = false)
@EnableConfigurationProperties({ ZuulProperties.class })
@ConditionalOnClass({ ZuulServlet.class, ZuulServletFilter.class })
@ConditionalOnBean(ZuulServerMarkerConfiguration.Marker.class)
// Make sure to get the ServerProperties from the same place as a normal web app would
// FIXME @Import(ServerPropertiesAutoConfiguration.class)
public class ZuulServerAutoConfiguration {
    @Bean
	@ConditionalOnMissingBean(name = "zuulServlet")
	@ConditionalOnProperty(name = "zuul.use-filter", havingValue = "false",
			matchIfMissing = true)
	public ServletRegistrationBean zuulServlet() {
		ServletRegistrationBean<ZuulServlet> servlet = new ServletRegistrationBean<>(
				new ZuulServlet(), this.zuulProperties.getServletPattern());
		// The whole point of exposing this servlet is to provide a route that doesn't
		// buffer requests.
		servlet.addInitParameter("buffer-requests", "false");
		return servlet;
	}

    // pre filters

	@Bean
	public ServletDetectionFilter servletDetectionFilter() {
		return new ServletDetectionFilter();
	}

	@Bean
	@ConditionalOnMissingBean
	public FormBodyWrapperFilter formBodyWrapperFilter() {
		return new FormBodyWrapperFilter();
	}

	@Bean
	@ConditionalOnMissingBean
	public DebugFilter debugFilter() {
		return new DebugFilter();
	}

	@Bean
	@ConditionalOnMissingBean
	public Servlet30WrapperFilter servlet30WrapperFilter() {
		return new Servlet30WrapperFilter();
	}

	// post filters

	@Bean
	public SendResponseFilter sendResponseFilter(ZuulProperties properties) {
		return new SendResponseFilter(zuulProperties);
	}

	@Bean
	public SendErrorFilter sendErrorFilter() {
		return new SendErrorFilter();
	}

	@Bean
	public SendForwardFilter sendForwardFilter() {
		return new SendForwardFilter();
	}

//
    @Configuration(proxyBeanMethods = false)
	protected static class ZuulFilterConfiguration {

		@Autowired
		private Map<String, ZuulFilter> filters;

		@Bean
		public ZuulFilterInitializer zuulFilterInitializer(CounterFactory counterFactory,
				TracerFactory tracerFactory) {
			FilterLoader filterLoader = FilterLoader.getInstance();
			FilterRegistry filterRegistry = FilterRegistry.instance();
			return new ZuulFilterInitializer(this.filters, counterFactory, tracerFactory,
					filterLoader, filterRegistry);
		}

	}
}

6)ZuulProxyAutoConfiguration配置类

继承了ZuulServerAutoConfiguration类，是ZuulServerAutoConfiguration的增强版，在ZuulServerAutoConfiguration的基础上增加eureka、ribbon、hystrix等功能。源码如下：

/**
 * @author Spencer Gibb
 * @author Dave Syer
 * @author Biju Kunjummen
 */
@Configuration(proxyBeanMethods = false)
@Import({ RibbonCommandFactoryConfiguration.RestClientRibbonConfiguration.class,
		RibbonCommandFactoryConfiguration.OkHttpRibbonConfiguration.class,
		RibbonCommandFactoryConfiguration.HttpClientRibbonConfiguration.class,
		HttpClientConfiguration.class })
@ConditionalOnBean(ZuulProxyMarkerConfiguration.Marker.class)
public class ZuulProxyAutoConfiguration extends ZuulServerAutoConfiguration {

    // pre filters
	@Bean
	@ConditionalOnMissingBean(PreDecorationFilter.class)
	public PreDecorationFilter preDecorationFilter(RouteLocator routeLocator,
			ProxyRequestHelper proxyRequestHelper) {
		return new PreDecorationFilter(routeLocator,
				this.server.getServlet().getContextPath(), this.zuulProperties,
				proxyRequestHelper);
	}

	// route filters
	@Bean
	@ConditionalOnMissingBean(RibbonRoutingFilter.class)
	public RibbonRoutingFilter ribbonRoutingFilter(ProxyRequestHelper helper,
			RibbonCommandFactory<?> ribbonCommandFactory) {
		RibbonRoutingFilter filter = new RibbonRoutingFilter(helper, ribbonCommandFactory,
				this.requestCustomizers);
		return filter;
	}

	@Bean
	@ConditionalOnMissingBean({ SimpleHostRoutingFilter.class,
			CloseableHttpClient.class })
	public SimpleHostRoutingFilter simpleHostRoutingFilter(ProxyRequestHelper helper,
			ZuulProperties zuulProperties,
			ApacheHttpClientConnectionManagerFactory connectionManagerFactory,
			ApacheHttpClientFactory httpClientFactory) {
		return new SimpleHostRoutingFilter(helper, zuulProperties,
				connectionManagerFactory, httpClientFactory);
	}

	@Bean
	@ConditionalOnMissingBean({ SimpleHostRoutingFilter.class })
	public SimpleHostRoutingFilter simpleHostRoutingFilter2(ProxyRequestHelper helper,
			ZuulProperties zuulProperties, CloseableHttpClient httpClient) {
		return new SimpleHostRoutingFilter(helper, zuulProperties, httpClient);
	}

	@Bean
	@ConditionalOnMissingBean(ServiceRouteMapper.class)
	public ServiceRouteMapper serviceRouteMapper() {
		return new SimpleServiceRouteMapper();
	}

	@Configuration(proxyBeanMethods = false)
	@ConditionalOnMissingClass("org.springframework.boot.actuate.health.Health")
	protected static class NoActuatorConfiguration {

		@Bean
		public ProxyRequestHelper proxyRequestHelper(ZuulProperties zuulProperties) {
			ProxyRequestHelper helper = new ProxyRequestHelper(zuulProperties);
			return helper;
		}

	}

	@Configuration(proxyBeanMethods = false)
	@ConditionalOnClass(Health.class)
	protected static class EndpointConfiguration {

		@Autowired(required = false)
		private HttpTraceRepository traces;

		@Bean
		@ConditionalOnAvailableEndpoint
		public RoutesEndpoint routesEndpoint(RouteLocator routeLocator) {
			return new RoutesEndpoint(routeLocator);
		}

		@ConditionalOnAvailableEndpoint
		@Bean
		public FiltersEndpoint filtersEndpoint() {
			FilterRegistry filterRegistry = FilterRegistry.instance();
			return new FiltersEndpoint(filterRegistry);
		}

		@Bean
		public ProxyRequestHelper proxyRequestHelper(ZuulProperties zuulProperties) {
			TraceProxyRequestHelper helper = new TraceProxyRequestHelper(zuulProperties);
			if (this.traces != null) {
				helper.setTraces(this.traces);
			}
			return helper;
		}

	}


}

2、核心类ZuulServlet

1）作用

调度不同阶段的filters，处理异常。所有的Request都要经过ZuulServlet的处理。三个核心的方法preRoute(),route(), postRoute()，zuul对request处理逻辑都在这三个方法里。源码如下：

public class ZuulServlet extends HttpServlet {

    private static final long serialVersionUID = -3374242278843351500L;
    private ZuulRunner zuulRunner;
    @Override
    public void init(ServletConfig config) throws ServletException {
        super.init(config);

        String bufferReqsStr = config.getInitParameter("buffer-requests");
        boolean bufferReqs = bufferReqsStr != null && bufferReqsStr.equals("true") ? true : false;

        zuulRunner = new ZuulRunner(bufferReqs);
    }

    @Override
    public void service(javax.servlet.ServletRequest servletRequest, javax.servlet.ServletResponse servletResponse) throws ServletException, IOException {
        try {
            init((HttpServletRequest) servletRequest, (HttpServletResponse) servletResponse);

            // Marks this request as having passed through the "Zuul engine", as opposed to servlets
            // explicitly bound in web.xml, for which requests will not have the same data attached
            RequestContext context = RequestContext.getCurrentContext();
            context.setZuulEngineRan();

            try {
                preRoute();
            } catch (ZuulException e) {
                error(e);
                postRoute();
                return;
            }
            try {
                route();
            } catch (ZuulException e) {
                error(e);
                postRoute();
                return;
            }
            try {
                postRoute();
            } catch (ZuulException e) {
                error(e);
                return;
            }

        } catch (Throwable e) {
            error(new ZuulException(e, 500, "UNHANDLED_EXCEPTION_" + e.getClass().getName()));
        } finally {
            RequestContext.getCurrentContext().unset();
        }
    }

    /**
     * executes "post" ZuulFilters
     *
     * @throws ZuulException
     */
    void postRoute() throws ZuulException {
        zuulRunner.postRoute();
    }

    /**
     * executes "route" filters
     *
     * @throws ZuulException
     */
    void route() throws ZuulException {
        zuulRunner.route();
    }

    /**
     * executes "pre" filters
     *
     * @throws ZuulException
     */
    void preRoute() throws ZuulException {
        zuulRunner.preRoute();
    }

    /**
     * initializes request
     *
     * @param servletRequest
     * @param servletResponse
     */
    void init(HttpServletRequest servletRequest, HttpServletResponse servletResponse) {
        zuulRunner.init(servletRequest, servletResponse);
    }

    /**
     * sets error context info and executes "error" filters
     *
     * @param e
     */
    void error(ZuulException e) {
        RequestContext.getCurrentContext().setThrowable(e);
        zuulRunner.error();
    }
}

2）调用链路：

以preRoute()为例：

1、ZuulServlet——》ZuulRunner，源码见四-2-1）；

2、ZuulRunner——》FilterProcessor，源码如下：

public void preRoute() throws ZuulException {
        FilterProcessor.getInstance().preRoute();
    }

3、FilterProcessor调自己的runFilters方法，涉及调用其他类：

FilterProcessor——》FilterLoader，源码见下方4

实际执行过滤器逻辑是在调用自己processZuulFilter方法中的下方的代码逻辑。

ZuulFilterResult result = filter.runFilter();（runFilter里面调用了子类的run方法）

public void preRoute() throws ZuulException {
        try {
            runFilters("pre");
        } catch (ZuulException e) {
            throw e;
        } catch (Throwable e) {
            throw new ZuulException(e, 500, "UNCAUGHT_EXCEPTION_IN_PRE_FILTER_" + e.getClass().getName());
        }
    }

    /**
     * runs all filters of the filterType sType/ Use this method within filters to run custom filters by type
     *
     * @param sType the filterType.
     * @return
     * @throws Throwable throws up an arbitrary exception
     */
    public Object runFilters(String sType) throws Throwable {
        if (RequestContext.getCurrentContext().debugRouting()) {
            Debug.addRoutingDebug("Invoking {" + sType + "} type filters");
        }
        boolean bResult = false;
        List<ZuulFilter> list = FilterLoader.getInstance().getFiltersByType(sType);
        if (list != null) {
            for (int i = 0; i < list.size(); i++) {
                ZuulFilter zuulFilter = list.get(i);
                Object result = processZuulFilter(zuulFilter);
                if (result != null && result instanceof Boolean) {
                    bResult |= ((Boolean) result);
                }
            }
        }
        return bResult;
    }

    public Object processZuulFilter(ZuulFilter filter) throws ZuulException {

        RequestContext ctx = RequestContext.getCurrentContext();
        boolean bDebug = ctx.debugRouting();
        final String metricPrefix = "zuul.filter-";
        long execTime = 0;
        String filterName = "";
        try {
            long ltime = System.currentTimeMillis();
            filterName = filter.getClass().getSimpleName();
            
            RequestContext copy = null;
            Object o = null;
            Throwable t = null;

            if (bDebug) {
                Debug.addRoutingDebug("Filter " + filter.filterType() + " " + filter.filterOrder() + " " + filterName);
                copy = ctx.copy();
            }
            
            ZuulFilterResult result = filter.runFilter();
            ExecutionStatus s = result.getStatus();
            execTime = System.currentTimeMillis() - ltime;

            switch (s) {
                case FAILED:
                    t = result.getException();
                    ctx.addFilterExecutionSummary(filterName, ExecutionStatus.FAILED.name(), execTime);
                    break;
                case SUCCESS:
                    o = result.getResult();
                    ctx.addFilterExecutionSummary(filterName, ExecutionStatus.SUCCESS.name(), execTime);
                    if (bDebug) {
                        Debug.addRoutingDebug("Filter {" + filterName + " TYPE:" + filter.filterType() + " ORDER:" + filter.filterOrder() + "} Execution time = " + execTime + "ms");
                        Debug.compareContextState(filterName, copy);
                    }
                    break;
                default:
                    break;
            }
            
            if (t != null) throw t;

            usageNotifier.notify(filter, s);
            return o;

        } catch (Throwable e) {
            if (bDebug) {
                Debug.addRoutingDebug("Running Filter failed " + filterName + " type:" + filter.filterType() + " order:" + filter.filterOrder() + " " + e.getMessage());
            }
            usageNotifier.notify(filter, ExecutionStatus.FAILED);
            if (e instanceof ZuulException) {
                throw (ZuulException) e;
            } else {
                ZuulException ex = new ZuulException(e, "Filter threw Exception", 500, filter.filterType() + ":" + filterName);
                ctx.addFilterExecutionSummary(filterName, ExecutionStatus.FAILED.name(), execTime);
                throw ex;
            }
        }
    }

4、FilterLoader——》filterRegistry，通过filterRegistry拿到所有的过滤器并筛选返回符合要求类型的集合并按优先级排序，放入缓存。

 /**
     * Returns a list of filters by the filterType specified
     *
     * @param filterType
     * @return a List<ZuulFilter>
     */
    public List<ZuulFilter> getFiltersByType(String filterType) {

        List<ZuulFilter> list = hashFiltersByType.get(filterType);
        if (list != null) return list;

        list = new ArrayList<ZuulFilter>();

        Collection<ZuulFilter> filters = filterRegistry.getAllFilters();
        for (Iterator<ZuulFilter> iterator = filters.iterator(); iterator.hasNext(); ) {
            ZuulFilter filter = iterator.next();
            if (filter.filterType().equals(filterType)) {
                list.add(filter);
            }
        }
        Collections.sort(list); // sort by priority

        hashFiltersByType.putIfAbsent(filterType, list);
        return list;
    }

5、FilterRegistry调用自己的getAllFilters方法返回所有的过滤器

private final ConcurrentHashMap<String, ZuulFilter> filters = new ConcurrentHashMap<String, ZuulFilter>();
public Collection<ZuulFilter> getAllFilters() {
        return this.filters.values();
    }

3、顶级抽象父类ZuulFilter

所有的过滤器都应继承该抽象类，重写shouldFilter、filterType、filterOrder、run方法。

shouldFilter：该过滤器是否生效返回true:有效；false：无效

filterType：指定过滤器类型，FilterConstants包含下面图中几种类型：filterOrder：在过滤器链中的顺序，返回值越小越靠前；

run：过滤器的逻辑。

public abstract class ZuulFilter implements IZuulFilter, Comparable<ZuulFilter> {

    abstract boolean shouldFilter();
    abstract Object run() throws ZuulException;
    abstract public String filterType();

    /**
     * filterOrder() must also be defined for a filter. Filters may have the same  filterOrder if precedence is not
     * important for a filter. filterOrders do not need to be sequential.
     *
     * @return the int order of a filter
     */
    abstract public int filterOrder();
    
    public int compareTo(ZuulFilter filter) {
        return Integer.compare(this.filterOrder(), filter.filterOrder());
    }
}

4、过滤器热加载

参考下方博客：

zuul 1.x 源码解析（结合本人过去2年工作经历整理，超详细）_zuulproxyautoconfiguration.predecorationfilter-CSDN博客文章浏览阅读428次，点赞6次，收藏4次。zuul 1.x 源码解析，全程断点调试，超详细（结合本人过去2年工作经历，花了1周时间整理并记录）_zuulproxyautoconfiguration.predecorationfilterhttps://blog.csdn.net/qq_22270363/article/details/132052278