回顧
Zuul是通過(guò)
ZuulServletFilter或者ZuulServlet接管我們的請(qǐng)求-
Zuul整個(gè)流程如下：
ZuulServletFilter(ZuulServlet)->ZuulRunner->FilterProcessor->ZuulFilter
目標(biāo)
明確SpringMVC和Zuul框架是怎么配合的
引入Zuul的版本信息
<properties>
<spring-cloud.version>Hoxton.RELEASE</spring-cloud.version>
</properties>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>${spring-cloud.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-zuul</artifactId>
</dependency>
</dependencies>
Zuul功能啟用及配置的加載
Zuul的啟用 - @EnableZuulProxy
// 引入斷路器功能
@EnableCircuitBreaker
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
// 注入觸發(fā)Zuul配置類的標(biāo)記Bean
@Import(ZuulProxyMarkerConfiguration.class)
public @interface EnableZuulProxy {
}
ZuulProxyAutoConfiguration - Zuul自動(dòng)配置Bean
// 此配置類不會(huì)被代理
@Configuration(proxyBeanMethods = false)
// 引入Ribbon相關(guān)配置
@Import({ RibbonCommandFactoryConfiguration.RestClientRibbonConfiguration.class,
RibbonCommandFactoryConfiguration.OkHttpRibbonConfiguration.class,
RibbonCommandFactoryConfiguration.HttpClientRibbonConfiguration.class,
HttpClientConfiguration.class })
@ConditionalOnBean(ZuulProxyMarkerConfiguration.Marker.class)
public class ZuulProxyAutoConfiguration extends ZuulServerAutoConfiguration {
// 省略部分代碼松捉。惶室。。
// 加載pre filters bean
@Bean
@ConditionalOnMissingBean(PreDecorationFilter.class)
public PreDecorationFilter preDecorationFilter(RouteLocator routeLocator,
ProxyRequestHelper proxyRequestHelper) {
return new PreDecorationFilter(routeLocator,
this.server.getServlet().getContextPath(), this.zuulProperties,
proxyRequestHelper);
}
// 加載route filters bean
@Bean
@ConditionalOnMissingBean(RibbonRoutingFilter.class)
public RibbonRoutingFilter ribbonRoutingFilter(ProxyRequestHelper helper,
RibbonCommandFactory<?> ribbonCommandFactory) {
RibbonRoutingFilter filter = new RibbonRoutingFilter(helper, ribbonCommandFactory,
this.requestCustomizers);
return filter;
}
// 加載route filters bean
@Bean
@ConditionalOnMissingBean({ SimpleHostRoutingFilter.class,
CloseableHttpClient.class })
public SimpleHostRoutingFilter simpleHostRoutingFilter(ProxyRequestHelper helper,
ZuulProperties zuulProperties,
ApacheHttpClientConnectionManagerFactory connectionManagerFactory,
ApacheHttpClientFactory httpClientFactory) {
return new SimpleHostRoutingFilter(helper, zuulProperties,
connectionManagerFactory, httpClientFactory);
}
}
ZuulServerAutoConfiguration - Zuul自動(dòng)配置Bean
@Configuration(proxyBeanMethods = false)
// 加載zuul的自定義properties配置
@EnableConfigurationProperties({ ZuulProperties.class })
// 加載前提：classpath下有類ZuulServlet和ZuulServletFilter
@ConditionalOnClass({ ZuulServlet.class, ZuulServletFilter.class })
@ConditionalOnBean(ZuulServerMarkerConfiguration.Marker.class)
public class ZuulServerAutoConfiguration {
// 省略部分代碼。。。
// ZuulController是Controller的一個(gè)實(shí)現(xiàn)，負(fù)責(zé)將攔截的請(qǐng)求交給ZuulServlet處理
@Bean
public ZuulController zuulController() {
return new ZuulController();
}
// ZuulHandlerMapping負(fù)責(zé)路由匹配
@Bean
public ZuulHandlerMapping zuulHandlerMapping(RouteLocator routes,
ZuulController zuulController) {
ZuulHandlerMapping mapping = new ZuulHandlerMapping(routes, zuulController);
mapping.setErrorController(this.errorController);
mapping.setCorsConfigurations(getCorsConfigurations());
return mapping;
}
// 默認(rèn)加載ZuulServlet
@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;
}
// 當(dāng)配置zuul.use-filter=true，加載zuulServletFilter, 表示用filter來(lái)攔截請(qǐng)求
@Bean
@ConditionalOnMissingBean(name = "zuulServletFilter")
@ConditionalOnProperty(name = "zuul.use-filter", havingValue = "true",
matchIfMissing = false)
public FilterRegistrationBean zuulServletFilter() {
final FilterRegistrationBean<ZuulServletFilter> filterRegistration = new FilterRegistrationBean<>();
filterRegistration.setUrlPatterns(
Collections.singleton(this.zuulProperties.getServletPattern()));
filterRegistration.setFilter(new ZuulServletFilter());
filterRegistration.setOrder(Ordered.LOWEST_PRECEDENCE);
// The whole point of exposing this servlet is to provide a route that doesn't
// buffer requests.
filterRegistration.addInitParameter("buffer-requests", "false");
return filterRegistration;
}
// 在Zuul各階段filter處理過(guò)程中捕獲異常颁独，SendErrorFilter會(huì)forward "/error"
@Bean
public SendErrorFilter sendErrorFilter() {
return new SendErrorFilter();
}
@Configuration(proxyBeanMethods = false)
protected static class ZuulFilterConfiguration {
// 注入Spring容器中的ZuulFilter類型所有的實(shí)現(xiàn)類，包括內(nèi)置和自定義的Filter伪冰，內(nèi)置的有10個(gè)
@Autowired
private Map<String, ZuulFilter> filters;
// 注冊(cè)ZuulFilter到FilterRegistry中
@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);
}
}
}
以上兩個(gè)類誓酒，加載了Zuul的相關(guān)配置類：
-
攔截請(qǐng)求：
- 和SpringMVC結(jié)合的Bean：
ZuulController、ZuulHandlerMapping - 通過(guò)Web Filter攔截請(qǐng)求Bean：
ZuulServletFilter
- 和SpringMVC結(jié)合的Bean：
-
Zuul流程需要的Bean：
自帶的ZuulFilter糜值，有10個(gè)下面會(huì)一一介紹
監(jiān)控相關(guān)
ZuulFilter的容器：
FilterRegistry
默認(rèn)的ZuulFilters
Pre Filter
-
ServletDetectionFilterorder = -3作用：判斷請(qǐng)求是否是由
DispatcherServletorZuulServlet傳來(lái)的丰捷，并把判斷結(jié)果以鍵值對(duì)的形式放在RequestContext -
Servlet30WrapperFilterorder = -2作用：包裝request，兼容servlet3.0
-
FormBodyWrapperFilterorder = -1作用：包裝表單數(shù)據(jù)并為下游服務(wù)重新編碼
-
DebugFilterorder = 1作用：如果debug請(qǐng)求寂汇，那么會(huì)在
RequestContext中標(biāo)記為debug請(qǐng)求和routing -
PreDecorationFilter= 5作用：請(qǐng)求路由和zuul路由配置進(jìn)行匹配病往，并設(shè)置與代理相關(guān)的頭部信息
Route Filter
-
RibbonRoutingFilterorder = 10作用：使用Ribbon、Hytrix和可插拔的httpClient發(fā)送請(qǐng)求骄瓣，serviceId停巷、是否重試以及負(fù)載均衡策略在相關(guān)聯(lián)的
RequestContext獲取 -
SimpleHostRoutingFilterorder = 100作用：用HttpClient發(fā)送請(qǐng)求到預(yù)定的URLs，URLs通過(guò)
RequestContext#getRouteHost()獲取 -
SendForwardFilterorder = 500作用：用
RequestDispatcherforwards請(qǐng)求，轉(zhuǎn)發(fā)的地址是RequestContext的FilterConstants#FORWARD_TO_KEY對(duì)應(yīng)value
Post Filter
-
SendResponseFilterorder = 1000作用：寫 代理的請(qǐng)求得到的響應(yīng) 到 當(dāng)前響應(yīng)
Error Filter
-
SendErrorFilterorder = 0作用：如果
RequestContext#getThrowable()不為空畔勤，默認(rèn)將請(qǐng)求轉(zhuǎn)發(fā)到 /error
SpringMVC怎么把請(qǐng)求轉(zhuǎn)發(fā)給Zuul蕾各？
從配置類分析
從上述配置可以看下幾個(gè)重要的配置類源碼：
ZuulController
public class ZuulController extends ServletWrappingController {
public ZuulController() {
// 設(shè)置Servlet的類型
setServletClass(ZuulServlet.class);
setServletName("zuul");
setSupportedMethods((String[]) null); // Allow all
}
@Override
public ModelAndView handleRequest(HttpServletRequest request,
HttpServletResponse response) throws Exception {
try {
// We don't care about the other features of the base class, just want to
// handle the request
return super.handleRequestInternal(request, response);
}
finally {
// @see com.netflix.zuul.context.ContextLifecycleFilter.doFilter
RequestContext.getCurrentContext().unset();
}
}
}
ServletWrappingController
public class ServletWrappingController extends AbstractController implements BeanNameAware, InitializingBean, DisposableBean {
// 省略代碼。庆揪。
@Override
public void afterPropertiesSet() throws Exception {
if (this.servletClass == null) {
throw new IllegalArgumentException("'servletClass' is required");
}
if (this.servletName == null) {
this.servletName = this.beanName;
}
// 通過(guò)反射 初始化servlet
this.servletInstance = ReflectionUtils.accessibleConstructor(this.servletClass).newInstance();
this.servletInstance.init(new DelegatingServletConfig());
}
// 通過(guò)servlet實(shí)例處理請(qǐng)求
@Override
protected ModelAndView handleRequestInternal(HttpServletRequest request, HttpServletResponse response)
throws Exception {
Assert.state(this.servletInstance != null, "No Servlet instance");
this.servletInstance.service(request, response);
return null;
}
}
ZuulHandlerMapping
public class ZuulHandlerMapping extends AbstractUrlHandlerMapping {
private final ZuulController zuul;
private volatile boolean dirty = true;
// 根據(jù)尋找路由處理器
@Override
protected Object lookupHandler(String urlPath, HttpServletRequest request) throws Exception {
if (this.errorController != null && urlPath.equals(this.errorController.getErrorPath())) {
return null;
}
// 如果屬于配置的忽視路由式曲，則返回null
if (isIgnoredPath(urlPath, this.routeLocator.getIgnoredPaths())) return null;
RequestContext ctx = RequestContext.getCurrentContext();
if (ctx.containsKey("forward.to")) {
return null;
}
if (this.dirty) {
// dirty默認(rèn)為true，第一次會(huì)觸發(fā)注冊(cè)處理器到Spring容器中
// 或者發(fā)送zuul路由刷新事件缸榛，設(shè)置dirty為true吝羞，見ZuulRefreshListener
synchronized (this) {
if (this.dirty) {
registerHandlers();
this.dirty = false;
}
}
}
// 交給Spring查找路由對(duì)應(yīng)的handler
return super.lookupHandler(urlPath, request);
}
// 注冊(cè)配置路由對(duì)應(yīng)的處理器
private void registerHandlers() {
Collection<Route> routes = this.routeLocator.getRoutes();
if (routes.isEmpty()) {
this.logger.warn("No routes found from RouteLocator");
}
else {
for (Route route : routes) {
// 在Spring容器中注冊(cè)zuul路由配置對(duì)應(yīng)ZuulController處理器
registerHandler(route.getFullPath(), this.zuul);
}
}
}
}
以上配置類：
-
ZuulController：它是ServletWrappingController的 子類，其屬性包含了ZuulServlet内颗， -
ZuulHandlerMapping：它是AbstractUrlHandlerMapping的子類 -
ZuulServlet：由上一篇知道它是Zuul流程的入口之一
回顧SpingMVC對(duì)于請(qǐng)求的處理流程
- 客戶端請(qǐng)求交給SpringMVC的
DispatcherServlet統(tǒng)一處理- 通過(guò)已經(jīng)注冊(cè)的
HandlerMapping, 根據(jù)請(qǐng)求路由找到處理器執(zhí)行鏈HandlerExecutionChain钧排，包括請(qǐng)求各個(gè)攔截器HandlerInterceptor和請(qǐng)求處理器handler- 找到請(qǐng)求處理器對(duì)應(yīng)的適配器
HandlerAdapter- 執(zhí)行已注冊(cè)的各攔截器的
preHandle方法- 調(diào)用處理器處理請(qǐng)求，返回模型數(shù)據(jù)以及視圖
ModelAndView- 執(zhí)行已注冊(cè)的各攔截器的
postHandle方法- 根據(jù)給定的
ModelAndView進(jìn)行渲染- 響應(yīng)客戶端
結(jié)合SpingMVC對(duì)于請(qǐng)求的處理流程可以猜到均澳，當(dāng)請(qǐng)求給到SpringMVC的DispatcherServlet后恨溜，如果該路由是需要Zuul攔截的請(qǐng)求，那么會(huì)匹配到ZuulHandlerMapping找前，從而找到處理器ZuulController糟袁，之后在處理的時(shí)候，會(huì)交給ZuulServlet纸厉，后面的流程見上一篇文章系吭。
Debug驗(yàn)證
zuul攔截配置：
# zuul
# 是否啟用ZuulServletFilter
# zuul.use-filter=true
ribbon.ConnectTimeout = 30000
ribbon.ReadTimeout = 30000
ribbon.eureka.enabled = false
management.endpoints.web.exposure.include = *
zuul.routes.test.path = /test/**
zuul.routes.test.stripPrefix = false
test.ribbon.listOfServers = ${service.test}
service.test=http://127.0.0.1:8081/t/test
請(qǐng)求：curl -v http://127.0.0.1:8080/test
圖示過(guò)程：
匹配到ZuulController
執(zhí)行ZuulServlet
結(jié)果顯示：猜想是正確的五嫂。
大致流程：DispatcherServlet -> ZuulController -> ZuulServlet -> 執(zhí)行各階段ZuulFilters
ZuulServlet接管流程圖.png
ZuulServletFilter - 另一種攔截請(qǐng)求流程
配置
// 在類ZuulServerAutoConfiguration中加載
@Bean
@ConditionalOnMissingBean(name = "zuulServletFilter")
@ConditionalOnProperty(name = "zuul.use-filter", havingValue = "true",
matchIfMissing = false)
public FilterRegistrationBean zuulServletFilter() {
final FilterRegistrationBean<ZuulServletFilter> filterRegistration = new FilterRegistrationBean<>();
// URL匹配規(guī)則: /zuul
filterRegistration.setUrlPatterns(
Collections.singleton(this.zuulProperties.getServletPattern()));
filterRegistration.setFilter(new ZuulServletFilter());
filterRegistration.setOrder(Ordered.LOWEST_PRECEDENCE);
filterRegistration.addInitParameter("buffer-requests", "false");
return filterRegistration;
}
ZuulServletFilter的URL匹配規(guī)則是/zuul, 而且如果要是使得ZuulServletFilterBean加載颗品，必須在配置文件中，添加：zuul.use-filter=true沃缘，如圖：
# 是否啟用filter攔截
zuul.use-filter=true
zuul.routes.test.path = /zuul/test/**
zuul.routes.test.stripPrefix = false
test.ribbon.listOfServers = ${service.test}
service.test=http://127.0.0.1:8081
ZuulServletFilter源碼
public class ZuulServletFilter extends com.netflix.zuul.filters.ZuulServletFilter {
@Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse,
FilterChain filterChain) throws IOException, ServletException {
RequestContext context = RequestContext.getCurrentContext();
context.setZuulEngineRan();
super.doFilter(servletRequest, servletResponse, filterChain);
}
}
源碼很簡(jiǎn)單躯枢，在請(qǐng)求上下文添加了一個(gè)標(biāo)志位zuulEngineRan為true。并執(zhí)行父類com.netflix.zuul.filters.ZuulServletFilter的doFilter方法槐臀，進(jìn)而進(jìn)入了Zuul的核心流程當(dāng)中锄蹂，后面的流程我們已經(jīng)熟悉了。
其中要要注意下水慨，com.netflix.zuul.filters.ZuulServletFilter雖然是Filter得糜，但是并沒(méi)有在其doFilter方法中調(diào)用FilterChain的doFilter方法，我們可以回想下晰洒，如果是我們自己寫FIlter朝抖，一定會(huì)調(diào)用。之所以ZuulServletFilte沒(méi)有這么做谍珊，是因?yàn)樗庸苷?qǐng)求治宣，并不要Servlet來(lái)處理。
ZuulServletFilter
大致流程如圖：
ZuulServletFilter接管流程圖
總結(jié)
Zuul和SpringMVC結(jié)合并接管請(qǐng)求的方式主要有兩種：
- 在Spring容器中通過(guò)注冊(cè)請(qǐng)求處理器
ZuulController和路由處理器的映射ZuulHandlerMapping，做到請(qǐng)求的攔截侮邀，并內(nèi)置了一些ZuulFIlter保證請(qǐng)求的處理坏怪。 - 通過(guò)注冊(cè)
ZuulServletFilter,使用Filter方式接管請(qǐng)求，注意默認(rèn)的路徑匹配及生效配置
