springcloud Zuul动态路由的实现

前言

Zuul 是Netflix 提供的一个开源组件,致力于在云平台上提供动态路由，监控，弹性，安全等边缘服务的框架。也有很多公司使用它来作为网关的重要组成部分，碰巧今年公司的架构组决定自研一个网关产品，集动态路由，动态权限，限流配额等功能为一体，为其他部门的项目提供统一的外网调用管理，最终形成产品(这方面阿里其实已经有成熟的网关产品了，但是不太适用于个性化的配置，也没有集成权限和限流降级)。

不过这里并不想介绍整个网关的架构，而是想着重于讨论其中的一个关键点，并且也是经常在交流群中听人说起的：动态路由怎么做？

再阐释什么是动态路由之前，需要介绍一下架构的设计。

传统互联网架构图

上图是没有网关参与的一个最典型的互联网架构(本文中统一使用book代表应用实例，即真正提供服务的一个业务系统)

加入eureka的架构图

book注册到eureka注册中心中，zuul本身也连接着同一个eureka，可以拉取book众多实例的列表。服务中心的注册发现一直是值得推崇的一种方式，但是不适用与网关产品。因为我们的网关是面向众多的其他部门的已有或是异构架构的系统，不应该强求其他系统都使用eureka，这样是有侵入性的设计。

最终架构图

要强调的一点是，gateway最终也会部署多个实例，达到分布式的效果，在架构图中没有画出，请大家自行脑补。

本博客的示例使用最后一章架构图为例，带来动态路由的实现方式，会有具体的代码。

动态路由

动态路由需要达到可持久化配置，动态刷新的效果。如架构图所示，不仅要能满足从spring的配置文件properties加载路由信息，还需要从数据库加载我们的配置。另外一点是，路由信息在容器启动时就已经加载进入了内存，我们希望配置完成后，实施发布，动态刷新内存中的路由信息，达到不停机维护路由信息的效果。

zuul–HelloWorldDemo

项目结构

<groupId>com.sinosoft</groupId>
<artifactId>zuul-gateway-demo</artifactId>
<packaging>pom</packaging>
<version>1.0</version>

<parent>
 <groupId>org.springframework.boot</groupId>
 <artifactId>spring-boot-starter-parent</artifactId>
 <version>1.5.2.RELEASE</version>
</parent>

<modules>
 <module>gateway</module>
 <module>book</module>
</modules>

<dependencyManagement>
 <dependencies>
  <dependency>
   <groupId>org.springframework.cloud</groupId>
   <artifactId>spring-cloud-dependencies</artifactId>
   <version>Camden.SR6</version>
   <type>pom</type>
   <scope>import</scope>
  </dependency>
 </dependencies>
</dependencyManagement>

tip：springboot-1.5.2对应的springcloud的版本需要使用Camden.SR6，一开始想专门写这个demo时，只替换了springboot的版本1.4.0->1.5.2，结果启动就报错了，最后发现是版本不兼容的锅。

gateway项目：

启动类：GatewayApplication.java

@EnableZuulProxy
@SpringBootApplication
public class GatewayApplication {

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

}

配置：application.properties

#配置在配置文件中的路由信息
zuul.routes.books.url=http://localhost:8090
zuul.routes.books.path=/books/**
#不使用注册中心,会带来侵入性
ribbon.eureka.enabled=false
#网关端口
server.port=8080

book项目：

启动类：BookApplication.java

@RestController
@SpringBootApplication
public class BookApplication {

@RequestMapping(value = "/available")
public String available() {
 System.out.println("Spring in Action");
 return "Spring in Action";
}

@RequestMapping(value = "/checked-out")
public String checkedOut() {
 return "Spring Boot in Action";
}

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

配置类：application.properties

server.port=8090

测试访问：http://localhost:8080/books/available

上述demo是一个简单的静态路由，简单看下源码，zuul是怎么做到转发，路由的。

@Configuration
@EnableConfigurationProperties({ ZuulProperties.class })
@ConditionalOnClass(ZuulServlet.class)
@Import(ServerPropertiesAutoConfiguration.class)
public class ZuulConfiguration {

@Autowired
//zuul的配置文件,对应了application.properties中的配置信息
protected ZuulProperties zuulProperties;

@Autowired
protected ServerProperties server;

@Autowired(required = false)
private ErrorController errorController;

@Bean
public HasFeatures zuulFeature() {
 return HasFeatures.namedFeature("Zuul (Simple)", ZuulConfiguration.class);
}

//核心类，路由 * ，最最重要
@Bean
@ConditionalOnMissingBean(RouteLocator.class)
public RouteLocator routeLocator() {
 //默认配置的实现是SimpleRouteLocator.class
 return new SimpleRouteLocator(this.server.getServletPrefix(),
   this.zuulProperties);
}

//zuul的控制器，负责处理链路调用
@Bean
public ZuulController zuulController() {
 return new ZuulController();
}

//MVC HandlerMapping that maps incoming request paths to remote services.
@Bean
public ZuulHandlerMapping zuulHandlerMapping(RouteLocator routes) {
 ZuulHandlerMapping mapping = new ZuulHandlerMapping(routes, zuulController());
 mapping.setErrorController(this.errorController);
 return mapping;
}

//注册了一个路由刷新 * ，默认实现是ZuulRefreshListener.class，这个是我们动态路由的关键
@Bean
public ApplicationListener<ApplicationEvent> zuulRefreshRoutesListener() {
 return new ZuulRefreshListener();
}

@Bean
@ConditionalOnMissingBean(name = "zuulServlet")
public ServletRegistrationBean zuulServlet() {
 ServletRegistrationBean 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
public FormBodyWrapperFilter formBodyWrapperFilter() {
 return new FormBodyWrapperFilter();
}

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

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

// post filters

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

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

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

@Configuration
protected static class ZuulFilterConfiguration {

@Autowired
 private Map<String, ZuulFilter> filters;

@Bean
 public ZuulFilterInitializer zuulFilterInitializer() {
  return new ZuulFilterInitializer(this.filters);
 }

}

//上面提到的路由刷新 *
private static class ZuulRefreshListener
  implements ApplicationListener<ApplicationEvent> {

@Autowired
 private ZuulHandlerMapping zuulHandlerMapping;

private HeartbeatMonitor heartbeatMonitor = new HeartbeatMonitor();

@Override
 public void onApplicationEvent(ApplicationEvent event) {
  if (event instanceof ContextRefreshedEvent
    || event instanceof RefreshScopeRefreshedEvent
    || event instanceof RoutesRefreshedEvent) {
   //设置为脏,下一次匹配到路径时，如果发现为脏，则会去刷新路由信息
   this.zuulHandlerMapping.setDirty(true);
  }
  else if (event instanceof HeartbeatEvent) {
   if (this.heartbeatMonitor.update(((HeartbeatEvent) event).getValue())) {
    this.zuulHandlerMapping.setDirty(true);
   }
  }
 }

}

}

我们要解决动态路由的难题，第一步就得理解路由 * 的作用。

很失望，因为从接口关系来看，spring考虑到了路由刷新的需求，但是默认实现的SimpleRouteLocator没有实现RefreshableRouteLocator接口，看来我们只能借鉴DiscoveryClientRouteLocator去改造SimpleRouteLocator使其具备刷新能力。

public interface RefreshableRouteLocator extends RouteLocator {
void refresh();
}

DiscoveryClientRouteLocator比SimpleRouteLocator多了两个功能，第一是从DiscoveryClient（如Eureka）发现路由信息，之前的架构图已经给大家解释清楚了，我们不想使用eureka这种侵入式的网关模块，所以忽略它，第二是实现了RefreshableRouteLocator接口，能够实现动态刷新。

对SimpleRouteLocator.class的源码加一些注释，方便大家阅读：

public class SimpleRouteLocator implements RouteLocator {

//配置文件中的路由信息配置
private ZuulProperties properties;
//路径正则配置器,即作用于path:/books/**
private PathMatcher pathMatcher = new AntPathMatcher();

private String dispatcherServletPath = "/";
private String zuulServletPath;

private AtomicReference<Map<String, ZuulRoute>> routes = new AtomicReference<>();

public SimpleRouteLocator(String servletPath, ZuulProperties properties) {
 this.properties = properties;
 if (servletPath != null && StringUtils.hasText(servletPath)) {
  this.dispatcherServletPath = servletPath;
 }

this.zuulServletPath = properties.getServletPath();
}

//路由 * 和其他组件的交互，是最终把定位的Routes以list的方式提供出去,核心实现
@Override
public List<Route> getRoutes() {
 if (this.routes.get() == null) {
  this.routes.set(locateRoutes());
 }
 List<Route> values = new ArrayList<>();
 for (String url : this.routes.get().keySet()) {
  ZuulRoute route = this.routes.get().get(url);
  String path = route.getPath();
  values.add(getRoute(route, path));
 }
 return values;
}

@Override
public Collection<String> getIgnoredPaths() {
 return this.properties.getIgnoredPatterns();
}

//这个方法在网关产品中也很重要，可以根据实际路径匹配到Route来进行业务逻辑的操作，进行一些加工
@Override
public Route getMatchingRoute(final String path) {

if (log.isDebugEnabled()) {
  log.debug("Finding route for path: " + path);
 }

if (this.routes.get() == null) {
  this.routes.set(locateRoutes());
 }

if (log.isDebugEnabled()) {
  log.debug("servletPath=" + this.dispatcherServletPath);
  log.debug("zuulServletPath=" + this.zuulServletPath);
  log.debug("RequestUtils.isDispatcherServletRequest()="
    + RequestUtils.isDispatcherServletRequest());
  log.debug("RequestUtils.isZuulServletRequest()="
    + RequestUtils.isZuulServletRequest());
 }

String adjustedPath = adjustPath(path);

ZuulRoute route = null;
 if (!matchesIgnoredPatterns(adjustedPath)) {
  for (Entry<String, ZuulRoute> entry : this.routes.get().entrySet()) {
   String pattern = entry.getKey();
   log.debug("Matching pattern:" + pattern);
   if (this.pathMatcher.match(pattern, adjustedPath)) {
    route = entry.getValue();
    break;
   }
  }
 }
 if (log.isDebugEnabled()) {
  log.debug("route matched=" + route);
 }

return getRoute(route, adjustedPath);

}

private Route getRoute(ZuulRoute route, String path) {
 if (route == null) {
  return null;
 }
 String targetPath = path;
 String prefix = this.properties.getPrefix();
 if (path.startsWith(prefix) && this.properties.isStripPrefix()) {
  targetPath = path.substring(prefix.length());
 }
 if (route.isStripPrefix()) {
  int index = route.getPath().indexOf("*") - 1;
  if (index > 0) {
   String routePrefix = route.getPath().substring(0, index);
   targetPath = targetPath.replaceFirst(routePrefix, "");
   prefix = prefix + routePrefix;
  }
 }
 Boolean retryable = this.properties.getRetryable();
 if (route.getRetryable() != null) {
  retryable = route.getRetryable();
 }
 return new Route(route.getId(), targetPath, route.getLocation(), prefix,
   retryable,
   route.isCustomSensitiveHeaders() ? route.getSensitiveHeaders() : null);
}

//注意这个类并没有实现refresh接口，但是却提供了一个protected级别的方法,旨在让子类不需要重复维护一个private AtomicReference<Map<String, ZuulRoute>> routes = new AtomicReference<>();也可以达到刷新的效果
protected void doRefresh() {
 this.routes.set(locateRoutes());
}

//具体就是在这儿定位路由信息的，我们之后从数据库加载路由信息，主要也是从这儿改写
/**
 * Compute a map of path pattern to route. The default is just a static map from the
 * {@link ZuulProperties}, but subclasses can add dynamic calculations.
 */
protected Map<String, ZuulRoute> locateRoutes() {
 LinkedHashMap<String, ZuulRoute> routesMap = new LinkedHashMap<String, ZuulRoute>();
 for (ZuulRoute route : this.properties.getRoutes().values()) {
  routesMap.put(route.getPath(), route);
 }
 return routesMap;
}

protected boolean matchesIgnoredPatterns(String path) {
 for (String pattern : this.properties.getIgnoredPatterns()) {
  log.debug("Matching ignored pattern:" + pattern);
  if (this.pathMatcher.match(pattern, path)) {
   log.debug("Path " + path + " matches ignored pattern " + pattern);
   return true;
  }
 }
 return false;
}

private String adjustPath(final String path) {
 String adjustedPath = path;

if (RequestUtils.isDispatcherServletRequest()
   && StringUtils.hasText(this.dispatcherServletPath)) {
  if (!this.dispatcherServletPath.equals("/")) {
   adjustedPath = path.substring(this.dispatcherServletPath.length());
   log.debug("Stripped dispatcherServletPath");
  }
 }
 else if (RequestUtils.isZuulServletRequest()) {
  if (StringUtils.hasText(this.zuulServletPath)
    && !this.zuulServletPath.equals("/")) {
   adjustedPath = path.substring(this.zuulServletPath.length());
   log.debug("Stripped zuulServletPath");
  }
 }
 else {
  // do nothing
 }

log.debug("adjustedPath=" + path);
 return adjustedPath;
}

}

重写过后的自定义路由 * 如下：

public class CustomRouteLocator extends SimpleRouteLocator implements RefreshableRouteLocator{

public final static Logger logger = LoggerFactory.getLogger(CustomRouteLocator.class);

private JdbcTemplate jdbcTemplate;

private ZuulProperties properties;

public void setJdbcTemplate(JdbcTemplate jdbcTemplate){
 this.jdbcTemplate = jdbcTemplate;
}

public CustomRouteLocator(String servletPath, ZuulProperties properties) {
 super(servletPath, properties);
 this.properties = properties;
 logger.info("servletPath:{}",servletPath);
}

//父类已经提供了这个方法，这里写出来只是为了说明这一个方法很重要！！！
// @Override
// protected void doRefresh() {
//  super.doRefresh();
// }

@Override
public void refresh() {
 doRefresh();
}

@Override
protected Map<String, ZuulRoute> locateRoutes() {
 LinkedHashMap<String, ZuulRoute> routesMap = new LinkedHashMap<String, ZuulRoute>();
 //从application.properties中加载路由信息
 routesMap.putAll(super.locateRoutes());
 //从db中加载路由信息
 routesMap.putAll(locateRoutesFromDB());
 //优化一下配置
 LinkedHashMap<String, ZuulRoute> values = new LinkedHashMap<>();
 for (Map.Entry<String, ZuulRoute> entry : routesMap.entrySet()) {
  String path = entry.getKey();
  // Prepend with slash if not already present.
  if (!path.startsWith("/")) {
   path = "/" + path;
  }
  if (StringUtils.hasText(this.properties.getPrefix())) {
   path = this.properties.getPrefix() + path;
   if (!path.startsWith("/")) {
    path = "/" + path;
   }
  }
  values.put(path, entry.getValue());
 }
 return values;
}

private Map<String, ZuulRoute> locateRoutesFromDB(){
 Map<String, ZuulRoute> routes = new LinkedHashMap<>();
 List<ZuulRouteVO> results = jdbcTemplate.query("select * from gateway_api_define where enabled = true ",new BeanPropertyRowMapper<>(ZuulRouteVO.class));
 for (ZuulRouteVO result : results) {
  if(org.apache.commons.lang3.StringUtils.isBlank(result.getPath()) || org.apache.commons.lang3.StringUtils.isBlank(result.getUrl()) ){
   continue;
  }
  ZuulRoute zuulRoute = new ZuulRoute();
  try {
   org.springframework.beans.BeanUtils.copyProperties(result,zuulRoute);
  } catch (Exception e) {
   logger.error("=============load zuul route info from db with error==============",e);
  }
  routes.put(zuulRoute.getPath(),zuulRoute);
 }
 return routes;
}

public static class ZuulRouteVO {

/**
  * The ID of the route (the same as its map key by default).
  */
 private String id;

/**
  * The path (pattern) for the route, e.g. /foo/**.
  */
 private String path;

/**
  * The service ID (if any) to map to this route. You can specify a physical URL or
  * a service, but not both.
  */
 private String serviceId;

/**
  * A full physical URL to map to the route. An alternative is to use a service ID
  * and service discovery to find the physical address.
  */
 private String url;

/**
  * Flag to determine whether the prefix for this route (the path, minus pattern
  * patcher) should be stripped before forwarding.
  */
 private boolean stripPrefix = true;

/**
  * Flag to indicate that this route should be retryable (if supported). Generally
  * retry requires a service ID and ribbon.
  */
 private Boolean retryable;

private Boolean enabled;

public String getId() {
  return id;
 }

public void setId(String id) {
  this.id = id;
 }

public String getPath() {
  return path;
 }

public void setPath(String path) {
  this.path = path;
 }

public String getServiceId() {
  return serviceId;
 }

public void setServiceId(String serviceId) {
  this.serviceId = serviceId;
 }

public String getUrl() {
  return url;
 }

public void setUrl(String url) {
  this.url = url;
 }

public boolean isStripPrefix() {
  return stripPrefix;
 }

public void setStripPrefix(boolean stripPrefix) {
  this.stripPrefix = stripPrefix;
 }

public Boolean getRetryable() {
  return retryable;
 }

public void setRetryable(Boolean retryable) {
  this.retryable = retryable;
 }

public Boolean getEnabled() {
  return enabled;
 }

public void setEnabled(Boolean enabled) {
  this.enabled = enabled;
 }
}
}

配置这个自定义的路由 * ：

@Configuration
public class CustomZuulConfig {

@Autowired
ZuulProperties zuulProperties;
@Autowired
ServerProperties server;
@Autowired
JdbcTemplate jdbcTemplate;

@Bean
public CustomRouteLocator routeLocator() {
 CustomRouteLocator routeLocator = new CustomRouteLocator(this.server.getServletPrefix(), this.zuulProperties);
 routeLocator.setJdbcTemplate(jdbcTemplate);
 return routeLocator;
}

}

现在容器启动时，就可以从数据库和配置文件中一起加载路由信息了，离动态路由还差最后一步，就是实时刷新，前面已经说过了，默认的ZuulConfigure已经配置了事件 * ，我们只需要发送一个事件就可以实现刷新了。

public class RefreshRouteService {

@Autowired
ApplicationEventPublisher publisher;

@Autowired
RouteLocator routeLocator;

public void refreshRoute() {
 RoutesRefreshedEvent routesRefreshedEvent = new RoutesRefreshedEvent(routeLocator);
 publisher.publishEvent(routesRefreshedEvent);
}

}

具体的刷新流程其实就是从数据库重新加载了一遍，有人可能会问，为什么不自己是手动重新加载Locator.dorefresh？非要用事件去刷新。这牵扯到内部的zuul内部组件的工作流程，不仅仅是Locator本身的一个变量，具体想要了解的还得去看源码。

到这儿我们就实现了动态路由了，所以的实例代码和建表语句我会放到github上，下载的时候记得给我star QAQ ！！！

链接：https://github.com/lexburner/zuul-gateway-demo

来源：https://blog.csdn.net/u013815546/article/details/68944039