tomcat源码研读笔记—tomcat的接收请求之三 StandardHost接收请求

在研读StandardHost的时候，我们再查看下它的继承关系：

我们会发现其实它跟StandardEngine的继承关系是很相似的，只是变了个Host接口和多个个Deployer接口而已，其他都是一样的。

   同样的

1, 调用了ContainerBase中的Invoke方法

2，进而掉用了valve的invoke方法，而这里实现了valve接口的实现类是StandardHostValve

3，这个时候将会调用StandardHostValve的invoke方法了

  public void invoke(Request request, Responseresponse,

                       ValveContextvalveContext)

       throws IOException, ServletException {

 

       // Validate the request and response object types

       if (!(request.getRequest() instanceof HttpServletRequest) ||

           !(response.getResponse() instanceof HttpServletResponse)) {

           return;     // NOTE - Not muchelse we can do generically

       }

 

       // Select the Context to be used for this Request

       StandardHost host = (StandardHost) getContainer();

       Context context = (Context) host.map(request, true);

       if (context == null) {

           ((HttpServletResponse) response.getResponse()).sendError

                (HttpServletResponse.SC_INTERNAL_SERVER_ERROR,

                sm.getString("standardHost.noContext"));

           return;

       }

 

       // Bind the context CL to the current thread

       Thread.currentThread().setContextClassLoader

           (context.getLoader().getClassLoader());

 

       // Update the session last access time for our session (if any)

       HttpServletRequest hreq = (HttpServletRequest) request.getRequest();

       String sessionId = hreq.getRequestedSessionId();

       if (sessionId != null) {

           Manager manager = context.getManager();

           if (manager != null) {

                Session session =manager.findSession(sessionId);

                if ((session != null)&& session.isValid())

                   session.access();

           }

       }

 

       // Ask this Context to process this request

       context.invoke(request, response);

 

}

 

1，  这个时候根据StandardHost的StandardHostMapper，查看map方法

publicContainer map(Request request, boolean update) {

        // Has this request already beenmapped?

        if (update &&(request.getContext() != null))

            return (request.getContext());

 

        // Perform mapping on our request URI

        String uri = ((HttpRequest)request).getDecodedRequestURI();

        Context context = host.map(uri);

 

        // Update the request (if requested)and return the selected Context

        if (update) {

            request.setContext(context);

            if (context != null)

                ((HttpRequest)request).setContextPath(context.getPath());

            else

                ((HttpRequest)request).setContextPath(null);

        }

        return (context);

 

}

知道根据url返回了实现了context接口的standardContext

 

6、这时请求就转移到了standardContext的invoke方法上了

standardardHost的请求流程图：

StandardardHost的请求关系类图