An AsyncContext is created and initialized by a call to * {@link ServletRequest#startAsync()} or * {@link ServletRequest#startAsync(ServletRequest, ServletResponse)}. * Repeated invocations of these methods will return the same AsyncContext * instance, reinitialized as appropriate. * *
In the event that an asynchronous operation has timed out, the * container must run through these steps: *
This information may be used by filters invoked in the * outbound direction, after a request was put into * asynchronous mode, to determine whether any request and/or response * wrappers that they added during their inbound invocation need * to be preserved for the duration of the asynchronous operation, or may * be released. * * @return true if this AsyncContext was initialized with the original * request and response objects by calling * {@link ServletRequest#startAsync()}, or if it was initialized by * calling * {@link ServletRequest#startAsync(ServletRequest, ServletResponse)}, * and neither the ServletRequest nor ServletResponse arguments * carried any application-provided wrappers; false otherwise */ public boolean hasOriginalRequestAndResponse(); /** * Dispatches the request and response objects of this AsyncContext * to the servlet container. * *
If the asynchronous cycle was started with * {@link ServletRequest#startAsync(ServletRequest, ServletResponse)}, * and the request passed is an instance of HttpServletRequest, * then the dispatch is to the URI returned by * {@link javax.servlet.http.HttpServletRequest#getRequestURI}. * Otherwise, the dispatch is to the URI of the request when it was * last dispatched by the container. * *
The following sequence illustrates how this will work:
*
* // REQUEST dispatch to /url/A
* AsyncContext ac = request.startAsync();
* ...
* ac.dispatch(); // ASYNC dispatch to /url/A
*
* // FORWARD dispatch to /url/B
* getRequestDispatcher("/url/B").forward(request,response);
* // Start async operation from within the target of the FORWARD
* // dispatch
* ac = request.startAsync();
* ...
* ac.dispatch(); // ASYNC dispatch to /url/A
*
* // FORWARD dispatch to /url/B
* getRequestDispatcher("/url/B").forward(request,response);
* // Start async operation from within the target of the FORWARD
* // dispatch
* ac = request.startAsync(request,response);
* ...
* ac.dispatch(); // ASYNC dispatch to /url/B
*
This method returns immediately after passing the request * and response objects to a container managed thread, on which the * dispatch operation will be performed. * *
The dispatcher type of the request is set to * DispatcherType.ASYNC. Unlike * {@link RequestDispatcher#forward(ServletRequest, ServletResponse) * forward dispatches}, the response buffer and * headers will not be reset, and it is legal to dispatch even if the * response has already been committed. * *
Control over the request and response is delegated * to the dispatch target, and the response will be closed when the * dispatch target has completed execution, unless * {@link ServletRequest#startAsync()} or * {@link ServletRequest#startAsync(ServletRequest, ServletResponse)} * are called. * *
Any errors or exceptions that may occur during the execution * of this method must be caught and handled by the container, as * follows: *
There can be at most one asynchronous dispatch operation per * asynchronous cycle, which is started by a call to one of the * {@link ServletRequest#startAsync} methods. Any attempt to perform an * additional asynchronous dispatch operation within the same * asynchronous cycle will result in an IllegalStateException. * If startAsync is subsequently called on the dispatched request, * then any of the dispatch or {@link #complete} methods may be called. * * @throws IllegalStateException if one of the dispatch methods * has been called and the startAsync method has not been * called during the resulting dispatch, or if {@link #complete} * was called * * @see ServletRequest#getDispatcherType */ public void dispatch(); /** * Dispatches the request and response objects of this AsyncContext * to the given path. * *
The path parameter is interpreted in the same way * as in {@link ServletRequest#getRequestDispatcher(String)}, within * the scope of the {@link ServletContext} from which this * AsyncContext was initialized. * *
All path related query methods of the request must reflect the * dispatch target, while the original request URI, context path, * path info, servlet path, and query string may be recovered from * the {@link #ASYNC_REQUEST_URI}, {@link #ASYNC_CONTEXT_PATH}, * {@link #ASYNC_PATH_INFO}, {@link #ASYNC_SERVLET_PATH}, and * {@link #ASYNC_QUERY_STRING} attributes of the request. These * attributes will always reflect the original path elements, even under * repeated dispatches. * *
There can be at most one asynchronous dispatch operation per * asynchronous cycle, which is started by a call to one of the * {@link ServletRequest#startAsync} methods. Any attempt to perform an * additional asynchronous dispatch operation within the same * asynchronous cycle will result in an IllegalStateException. * If startAsync is subsequently called on the dispatched request, * then any of the dispatch or {@link #complete} methods may be called. * *
See {@link #dispatch()} for additional details, including error * handling. * * @param path the path of the dispatch target, scoped to the * ServletContext from which this AsyncContext was initialized * * @throws IllegalStateException if one of the dispatch methods * has been called and the startAsync method has not been * called during the resulting dispatch, or if {@link #complete} * was called * * @see ServletRequest#getDispatcherType */ public void dispatch(String path); /** * Dispatches the request and response objects of this AsyncContext * to the given path scoped to the given context. * *
The path parameter is interpreted in the same way * as in {@link ServletRequest#getRequestDispatcher(String)}, except that * it is scoped to the given context. * *
All path related query methods of the request must reflect the * dispatch target, while the original request URI, context path, * path info, servlet path, and query string may be recovered from * the {@link #ASYNC_REQUEST_URI}, {@link #ASYNC_CONTEXT_PATH}, * {@link #ASYNC_PATH_INFO}, {@link #ASYNC_SERVLET_PATH}, and * {@link #ASYNC_QUERY_STRING} attributes of the request. These * attributes will always reflect the original path elements, even under * repeated dispatches. * *
There can be at most one asynchronous dispatch operation per * asynchronous cycle, which is started by a call to one of the * {@link ServletRequest#startAsync} methods. Any attempt to perform an * additional asynchronous dispatch operation within the same * asynchronous cycle will result in an IllegalStateException. * If startAsync is subsequently called on the dispatched request, * then any of the dispatch or {@link #complete} methods may be called. * *
See {@link #dispatch()} for additional details, including error * handling. * * @param context the ServletContext of the dispatch target * @param path the path of the dispatch target, scoped to the given * ServletContext * * @throws IllegalStateException if one of the dispatch methods * has been called and the startAsync method has not been * called during the resulting dispatch, or if {@link #complete} * was called * * @see ServletRequest#getDispatcherType */ public void dispatch(ServletContext context, String path); /** * Completes the asynchronous operation that was started on the request * that was used to initialze this AsyncContext, closing the response * that was used to initialize this AsyncContext. * *
Any listeners of type {@link AsyncListener} that were registered * with the ServletRequest for which this AsyncContext was created will * be invoked at their {@link AsyncListener#onComplete(AsyncEvent) * onComplete} method. * *
It is legal to call this method any time after a call to * {@link ServletRequest#startAsync()} or * {@link ServletRequest#startAsync(ServletRequest, ServletResponse)}, * and before a call to one of the dispatch methods * of this class. * If this method is called before the container-initiated dispatch * that called startAsync has returned to the container, then * the call will not take effect (and any invocations of * {@link AsyncListener#onComplete(AsyncEvent)} will be delayed) until * after the container-initiated dispatch has returned to the container. */ public void complete(); /** * Causes the container to dispatch a thread, possibly from a managed * thread pool, to run the specified Runnable. The container may * propagate appropriate contextual information to the Runnable. * * @param run the asynchronous handler */ public void start(Runnable run); /** * Registers the given {@link AsyncListener} with the most recent * asynchronous cycle that was started by a call to one of the * {@link ServletRequest#startAsync} methods. * *
The given AsyncListener will receive an {@link AsyncEvent} when * the asynchronous cycle completes successfully, times out, or results * in an error. * *
AsyncListener instances will be notified in the order in which * they were added. * * @param listener the AsyncListener to be registered * * @throws IllegalStateException if this method is called after * the container-initiated dispatch, during which one of the * {@link ServletRequest#startAsync} methods was called, has * returned to the container */ public void addListener(AsyncListener listener); /** * Registers the given {@link AsyncListener} with the most recent * asynchronous cycle that was started by a call to one of the * {@link ServletRequest#startAsync} methods. * *
The given AsyncListener will receive an {@link AsyncEvent} when * the asynchronous cycle completes successfully, times out, or results * in an error. * *
AsyncListener instances will be notified in the order in which * they were added. * *
The given ServletRequest and ServletResponse objects will * be made available to the given AsyncListener via the * {@link AsyncEvent#getSuppliedRequest getSuppliedRequest} and * {@link AsyncEvent#getSuppliedResponse getSuppliedResponse} methods, * respectively, of the {@link AsyncEvent} delivered to it. These objects * should not be read from or written to, respectively, at the time the * AsyncEvent is delivered, because additional wrapping may have * occurred since the given AsyncListener was registered, but may be used * in order to release any resources associated with them. * * @param listener the AsyncListener to be registered * @param servletRequest the ServletRequest that will be included * in the AsyncEvent * @param servletResponse the ServletResponse that will be included * in the AsyncEvent * * @throws IllegalStateException if this method is called after * the container-initiated dispatch, during which one of the * {@link ServletRequest#startAsync} methods was called, has * returned to the container */ public void addListener(AsyncListener listener, ServletRequest servletRequest, ServletResponse servletResponse); /** * Instantiates the given {@link AsyncListener} class. * *
The returned AsyncListener instance may be further customized
* before it is registered with this AsyncContext via a call to one of
* the addListener methods.
*
*
The given AsyncListener class must define a zero argument * constructor, which is used to instantiate it. * *
This method supports resource injection if the given * clazz represents a Managed Bean. * See the Java EE platform and JSR 299 specifications for additional * details about Managed Beans and resource injection. *
This method supports any annotations applicable to AsyncListener.
*
* @param clazz the AsyncListener class to instantiate
*
* @return the new AsyncListener instance
*
* @throws ServletException if the given clazz fails to be
* instantiated
*/
public The timeout applies to this AsyncContext once the
* container-initiated dispatch during which one of the
* {@link ServletRequest#startAsync} methods was called has
* returned to the container.
*
* The timeout will expire if neither the {@link #complete} method
* nor any of the dispatch methods are called. A timeout value of
* zero or less indicates no timeout.
*
* If {@link #setTimeout} is not called, then the container's
* default timeout, which is available via a call to
* {@link #getTimeout}, will apply.
*
* @param timeout the timeout in milliseconds
*
* @throws IllegalStateException if this method is called after
* the container-initiated dispatch, during which one of the
* {@link ServletRequest#startAsync} methods was called, has
* returned to the container
*/
public void setTimeout(long timeout);
/**
* Gets the timeout (in milliseconds) for this AsyncContext.
*
* This method returns the container's default timeout for
* asynchronous operations, or the timeout value passed to the most
* recent invocation of {@link #setTimeout}.
*
* A timeout value of zero or less indicates no timeout.
*
* @return the timeout in milliseconds
*/
public long getTimeout();
}