網關zuul——請求流轉路徑

網關Zuul——url請求流轉路徑

在springcloud的網關組件zuul中，網關本身能夠接收url請求,那么請求在網關zuul組件中是怎么流轉的呢？

從前面的文章可以看出，當外部請求傳遞到網關（Zuul）時，請求會傳遞到ZuulController類中

public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception {
        ModelAndView var3;
        try {
            var3 = super.handleRequestInternal(request, response);
        } finally {
            RequestContext.getCurrentContext().unset();
        }

        return var3;
    }

這里可以看出，外部請求會進入ZuulController類中，交由handleRequest方法處理，而該方法實際調用其父類的handleRequestInternal方法

查看ZuulController的父類ServletWrappingController

protected ModelAndView handleRequestInternal(HttpServletRequest request, HttpServletResponse response) throws Exception {
        Assert.state(this.servletInstance != null, "No Servlet instance");
        this.servletInstance.service(request, response);
        return null;
    }

在ServletWrappingController類的handleRequestInternal方法中，請求是由ZuulServlet的service方法處理

public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
        try {
            this.init((HttpServletRequest)servletRequest, (HttpServletResponse)servletResponse);
            RequestContext context = RequestContext.getCurrentContext();
            context.setZuulEngineRan();

            try {
                this.preRoute();
            } catch (ZuulException var12) {
                this.error(var12);
                this.postRoute();
                return;
            }

            try {
                this.route();
            } catch (ZuulException var13) {
                this.error(var13);
                this.postRoute();
                return;
            }

            try {
                this.postRoute();
            } catch (ZuulException var11) {
                this.error(var11);
            }
        } catch (Throwable var14) {
            this.error(new ZuulException(var14, 500, "UNHANDLED_EXCEPTION_" + var14.getClass().getName()));
        } finally {
            RequestContext.getCurrentContext().unset();
        }
    }

//處理http請求
 void init(HttpServletRequest servletRequest, HttpServletResponse servletResponse) {
        this.zuulRunner.init(servletRequest, servletResponse);
    }

從上述代碼可以看出，http請求會傳遞到ZuulRunner類中進行處理

查看ZuulRunner中的處理方式

   public void init(HttpServletRequest servletRequest, HttpServletResponse servletResponse) {
        RequestContext ctx = RequestContext.getCurrentContext();
        if (this.bufferRequests) {
            ctx.setRequest(new HttpServletRequestWrapper(servletRequest));
        } else {
            ctx.setRequest(servletRequest);
        }

        ctx.setResponse(new HttpServletResponseWrapper(servletResponse));
    }

查看上述代碼，可以看出請求最后被存放在RequestContext類中，而RequestContext是一個靜態單例的，所以在程序的任何位置都可以通過獲取RequestContext的實例來獲取到http請求信息。而這也就是過濾器用以進行請求過濾的基礎。

 

總結:

http請求的流轉路徑：

ZuulController的handleRequest方法——>ServletWrappingController的handleRequestInternal方法——>ZuulServlet的service方法——>ZuulServlet的init方法——>

ZuulRunner的init方法——>RequestContext的實例中