tomcat源码解析--StandardContextValve

290112011

　　standardContext 的 基础阀 StandardContextValve
　　主要方法invoke()

// 判断 request 的请求路径是否符合规范
MessageBytes requestPathMB = request.getRequestPathMB();
if ((requestPathMB.startsWithIgnoreCase("/META-INF/", 0))
|| (requestPathMB.equalsIgnoreCase("/META-INF"))
|| (requestPathMB.startsWithIgnoreCase("/WEB-INF/", 0))
|| (requestPathMB.equalsIgnoreCase("/WEB-INF"))) {
notFound(response);
return;
}
// Wait if we are reloading
boolean reloaded = false;
//是否暂停（如果暂停肯定是在reload）
while (context.getPaused()) {
reloaded = true;
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
;
}
}
// Reloading will have stopped the old webappclassloader and
// created a new one
if (reloaded &&
context.getLoader() != null &&
context.getLoader().getClassLoader() != null) {
//reload时，重新设置一个classloader
Thread.currentThread().setContextClassLoader(
context.getLoader().getClassLoader());
}
// Select the Wrapper to be used for this Request
//请求的servlet
Wrapper wrapper = request.getWrapper();
if (wrapper == null) {
notFound(response);
return;
} else if (wrapper.isUnavailable()) {
// May be as a result of a reload, try and find the new wrapper
wrapper = (Wrapper) container.findChild(wrapper.getName());
if (wrapper == null) {
notFound(response);
return;
}
}
// Normal request processing
//得到所有的监听
Object instances[] = context.getApplicationEventListeners();
ServletRequestEvent event = null;
if ((instances != null)
&& (instances.length > 0)) {
event = new ServletRequestEvent
(((StandardContext) container).getServletContext(),
request.getRequest());
// create pre-service event
for (int i = 0; i < instances.length; i++) {
if (instances == null)
continue;
if (!(instances instanceof ServletRequestListener))
continue;
//只处理其中的ServletRequestEvent
ServletRequestListener listener =
(ServletRequestListener) instances;
try {
//触发监听的事件
listener.requestInitialized(event);
} catch (Throwable t) {
container.getLogger().error(sm.getString("standardContext.requestListener.requestInit",
instances.getClass().getName()), t);
ServletRequest sreq = request.getRequest();
sreq.setAttribute(Globals.EXCEPTION_ATTR,t);
return;
}
}
}
//在context 的基础阀 中 调用pipeline中load的所有wrapper的value
wrapper.getPipeline().getFirst().invoke(request, response)
if ((instances !=null ) &&
(instances.length > 0)) {
// create post-service event
for (int i = 0; i < instances.length; i++) {
if (instances == null)
continue;
if (!(instances instanceof ServletRequestListener))
continue;
ServletRequestListener listener =
(ServletRequestListener) instances;
try {
//servlet 调用结束之后，触发的销毁事件
listener.requestDestroyed(event);
} catch (Throwable t) {
container.getLogger().error(sm.getString("standardContext.requestListener.requestDestroy",
instances.getClass().getName()), t);
ServletRequest sreq = request.getRequest();
sreq.setAttribute(Globals.EXCEPTION_ATTR,t);
}
}
}