Springcloud之zuul的ZuulController
Springcloud的版本是Greenwich.SR2，Springboot版本是2.1.6.release.
最近使用到Springcloud的zuul，分析了下源码，记录下，如下的List-1，主要是zuulHandlerMapping方法，构造ZuulHandlerMapping时，传入的RouteLocator是CompositeRouteLocator，而this.zuulController()返回的是ZuulController类。
List-1
@Bean
public ZuulController zuulController() {
return new ZuulController();
}
@Bean
public ZuulHandlerMapping zuulHandlerMapping(RouteLocator routes) {
ZuulHandlerMapping mapping = new ZuulHandlerMapping(routes, this.zuulController());
mapping.setErrorController(this.errorController);
mapping.setCorsConfigurations(this.getCorsConfigurations());
return mapping;
}如下图1所示，ZuulHandlerMapping继承了AbstractUrlHandlerMapping，如果了解Springmvc，就对这个应该熟悉点了。ZuulHandlerMapping复写了父类的lookupHandler，目的是将url-->controller这个映射关系注册到Springmvc中，如List-2所示。
图1
如下List-2，registerHandlers方法中，遍历所有的Route，之后将这些Route的处理类设置为ZuulController。routeLocator的实现有三个，分别是SimpleRouteLocator、DiscoveryClientRouteLocator、DiscoveryClientRouteLocator。
List-2
private final ZuulController zuul;
@Override
protected Object lookupHandler(String urlPath, HttpServletRequest request)
throws Exception {
if (this.errorController != null
&& urlPath.equals(this.errorController.getErrorPath())) {
return null;
}
if (isIgnoredPath(urlPath, this.routeLocator.getIgnoredPaths())) {
return null;
}
RequestContext ctx = RequestContext.getCurrentContext();
if (ctx.containsKey("forward.to")) {
return null;
}
if (this.dirty) {
synchronized (this) {
if (this.dirty) {
registerHandlers();
this.dirty = false;
}
}
}
return super.lookupHandler(urlPath, request);
}
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) {
registerHandler(route.getFullPath(), this.zuul);
}
}
}上面分析，知道了由ZuulController来处理，那么来看下ZuulController，如下List-3所示，如果去看ZuulController的父类ServletWrappingController，会看到，是将请求交给ZuulServlet来处理，ZuulServlet和ZuulFilter是如何结合起来处理的，看另一篇博客。
List-3
public class ZuulController extends ServletWrappingController {
public ZuulController() {
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();
}
}
}到此，我们知道Zuul是如何将Route路由信息(我们在springboot application.yml中配置的)映射到ZuulController，而后ZuulController委托给ZuulServlet来处理。
Reference
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