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 clientinstance:hostname: localhostinstance-id: taxi-online-zuul # 实例id3、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 {@Beanpublic 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@Beanpublic ServletDetectionFilter servletDetectionFilter() {return new ServletDetectionFilter();}@Bean@ConditionalOnMissingBeanpublic FormBodyWrapperFilter formBodyWrapperFilter() {return new FormBodyWrapperFilter();}@Bean@ConditionalOnMissingBeanpublic DebugFilter debugFilter() {return new DebugFilter();}@Bean@ConditionalOnMissingBeanpublic Servlet30WrapperFilter servlet30WrapperFilter() {return new Servlet30WrapperFilter();}// post filters@Beanpublic SendResponseFilter sendResponseFilter(ZuulProperties properties) {return new SendResponseFilter(zuulProperties);}@Beanpublic SendErrorFilter sendErrorFilter() {return new SendErrorFilter();}@Beanpublic SendForwardFilter sendForwardFilter() {return new SendForwardFilter();}//@Configuration(proxyBeanMethods = false)protected static class ZuulFilterConfiguration {@Autowiredprivate Map<String, ZuulFilter> filters;@Beanpublic 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 {@Beanpublic 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@ConditionalOnAvailableEndpointpublic RoutesEndpoint routesEndpoint(RouteLocator routeLocator) {return new RoutesEndpoint(routeLocator);}@ConditionalOnAvailableEndpoint@Beanpublic FiltersEndpoint filtersEndpoint() {FilterRegistry filterRegistry = FilterRegistry.instance();return new FiltersEndpoint(filterRegistry);}@Beanpublic 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;@Overridepublic 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);}@Overridepublic 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 attachedRequestContext 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 priorityhashFiltersByType.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
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