public interface AsyncContext
An AsyncContext is created and initialized by a call to
ServletRequest.startAsync()
or
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:
onTimeout
method, all
AsyncListener
instances registered with the ServletRequest
on which the asynchronous operation was initiated.complete()
or any of the
dispatch()
methods, perform an error dispatch with a status code
equal to HttpServletResponse.SC_INTERNAL_SERVER_ERROR.complete()
or any of the dispatch()
methods, call
complete()
.Modifier and Type | Field and Description |
---|---|
static String |
ASYNC_CONTEXT_PATH
The name of the request attribute under which the original
context path is made available to the target of a
dispatch(String) or dispatch(ServletContext,String) |
static String |
ASYNC_PATH_INFO
The name of the request attribute under which the original
path info is made available to the target of a
dispatch(String) or dispatch(ServletContext,String) |
static String |
ASYNC_QUERY_STRING
The name of the request attribute under which the original
query string is made available to the target of a
dispatch(String) or dispatch(ServletContext,String) |
static String |
ASYNC_REQUEST_URI
The name of the request attribute under which the original
request URI is made available to the target of a
dispatch(String) or dispatch(ServletContext,String) |
static String |
ASYNC_SERVLET_PATH
The name of the request attribute under which the original
servlet path is made available to the target of a
dispatch(String) or dispatch(ServletContext,String) |
Modifier and Type | Method and Description |
---|---|
void |
addListener(AsyncListener listener)
Registers the given
AsyncListener with the most recent
asynchronous cycle that was started by a call to one of the
ServletRequest.startAsync() methods. |
void |
addListener(AsyncListener listener,
ServletRequest servletRequest,
ServletResponse servletResponse)
Registers the given
AsyncListener with the most recent
asynchronous cycle that was started by a call to one of the
ServletRequest.startAsync() methods. |
void |
complete()
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.
|
<T extends AsyncListener> |
createListener(Class<T> clazz)
Instantiates the given
AsyncListener class. |
void |
dispatch()
Dispatches the request and response objects of this AsyncContext
to the servlet container.
|
void |
dispatch(ServletContext context,
String path)
Dispatches the request and response objects of this AsyncContext
to the given path scoped to the given context.
|
void |
dispatch(String path)
Dispatches the request and response objects of this AsyncContext
to the given path.
|
ServletRequest |
getRequest()
Gets the request that was used to initialize this AsyncContext
by calling
ServletRequest.startAsync() or
ServletRequest.startAsync(ServletRequest, ServletResponse) . |
ServletResponse |
getResponse()
Gets the response that was used to initialize this AsyncContext
by calling
ServletRequest.startAsync() or
ServletRequest.startAsync(ServletRequest, ServletResponse) . |
long |
getTimeout()
Gets the timeout (in milliseconds) for this AsyncContext.
|
boolean |
hasOriginalRequestAndResponse()
Checks if this AsyncContext was initialized with the original or
application-wrapped request and response objects.
|
void |
setTimeout(long timeout)
Sets the timeout (in milliseconds) for this AsyncContext.
|
void |
start(Runnable run)
Causes the container to dispatch a thread, possibly from a managed
thread pool, to run the specified Runnable.
|
static final String ASYNC_REQUEST_URI
dispatch(String)
or dispatch(ServletContext,String)
static final String ASYNC_CONTEXT_PATH
dispatch(String)
or dispatch(ServletContext,String)
static final String ASYNC_PATH_INFO
dispatch(String)
or dispatch(ServletContext,String)
static final String ASYNC_SERVLET_PATH
dispatch(String)
or dispatch(ServletContext,String)
static final String ASYNC_QUERY_STRING
dispatch(String)
or dispatch(ServletContext,String)
ServletRequest getRequest()
ServletRequest.startAsync()
or
ServletRequest.startAsync(ServletRequest, ServletResponse)
.IllegalStateException
- if complete()
or any of the
dispatch()
methods has been
called in the asynchronous cycleServletResponse getResponse()
ServletRequest.startAsync()
or
ServletRequest.startAsync(ServletRequest, ServletResponse)
.IllegalStateException
- if complete()
or any of the
dispatch()
methods has been
called in the asynchronous cycleboolean hasOriginalRequestAndResponse()
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.
ServletRequest.startAsync()
, or if it was initialized by
calling
ServletRequest.startAsync(ServletRequest, ServletResponse)
,
and neither the ServletRequest nor ServletResponse arguments
carried any application-provided wrappers; false otherwisevoid dispatch()
If the asynchronous cycle was started with
ServletRequest.startAsync(ServletRequest, ServletResponse)
,
and the request passed is an instance of HttpServletRequest,
then the dispatch is to the URI returned by
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
// REQUEST to /url/A
// FORWARD dispatch to /url/B
request.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
// REQUEST to /url/A
// FORWARD dispatch to /url/B
request.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. If this method is called before the container-initiated dispatch that called startAsync has returned to the container, the dispatch operation will be delayed until after the container-initiated dispatch has returned to the container.
The dispatcher type of the request is set to
DispatcherType.ASYNC. Unlike
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
ServletRequest.startAsync()
or
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:
onError
method, all
AsyncListener
instances registered with the ServletRequest
for which this AsyncContext was created, and make the caught
Throwable available via AsyncEvent.getThrowable()
.complete()
or any of the
dispatch()
methods, perform an error dispatch with a status code
equal to HttpServletResponse.SC_INTERNAL_SERVER_ERROR, and
make the above Throwable available as the value of the
RequestDispatcher.ERROR_EXCEPTION request attribute.complete()
or any of the dispatch()
methods, call
complete()
.There can be at most one asynchronous dispatch operation per
asynchronous cycle, which is started by a call to one of the
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 complete()
methods may be called.
IllegalStateException
- if one of the dispatch methods
has been called and the startAsync method has not been
called during the resulting dispatch, or if complete()
was calledServletRequest.getDispatcherType()
void dispatch(String path)
The path parameter is interpreted in the same way
as in ServletRequest.getRequestDispatcher(String)
, within
the scope of the 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 ASYNC_REQUEST_URI
, ASYNC_CONTEXT_PATH
,
ASYNC_PATH_INFO
, ASYNC_SERVLET_PATH
, and
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
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 complete()
methods may be called.
See dispatch()
for additional details, including error
handling.
path
- the path of the dispatch target, scoped to the
ServletContext from which this AsyncContext was initializedIllegalStateException
- if one of the dispatch methods
has been called and the startAsync method has not been
called during the resulting dispatch, or if complete()
was calledServletRequest.getDispatcherType()
void dispatch(ServletContext context, String path)
The path parameter is interpreted in the same way
as in 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 ASYNC_REQUEST_URI
, ASYNC_CONTEXT_PATH
,
ASYNC_PATH_INFO
, ASYNC_SERVLET_PATH
, and
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
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 complete()
methods may be called.
See dispatch()
for additional details, including error
handling.
context
- the ServletContext of the dispatch targetpath
- the path of the dispatch target, scoped to the given
ServletContextIllegalStateException
- if one of the dispatch methods
has been called and the startAsync method has not been
called during the resulting dispatch, or if complete()
was calledServletRequest.getDispatcherType()
void complete()
Any listeners of type AsyncListener
that were registered
with the ServletRequest for which this AsyncContext was created will
be invoked at their onComplete
method.
It is legal to call this method any time after a call to
ServletRequest.startAsync()
or
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
AsyncListener.onComplete(AsyncEvent)
will be delayed) until
after the container-initiated dispatch has returned to the container.
void start(Runnable run)
run
- the asynchronous handlervoid addListener(AsyncListener listener)
AsyncListener
with the most recent
asynchronous cycle that was started by a call to one of the
ServletRequest.startAsync()
methods.
The given AsyncListener will receive an AsyncEvent
when
the asynchronous cycle completes successfully, times out, results
in an error, or a new asynchronous cycle is being initiated via
one of the ServletRequest.startAsync()
methods.
AsyncListener instances will be notified in the order in which they were added.
If ServletRequest.startAsync(ServletRequest, ServletResponse)
or ServletRequest.startAsync()
is called,
the exact same request and response objects are available from the
AsyncEvent
when the AsyncListener
is notified.
listener
- the AsyncListener to be registeredIllegalStateException
- if this method is called after
the container-initiated dispatch, during which one of the
ServletRequest.startAsync()
methods was called, has
returned to the containervoid addListener(AsyncListener listener, ServletRequest servletRequest, ServletResponse servletResponse)
AsyncListener
with the most recent
asynchronous cycle that was started by a call to one of the
ServletRequest.startAsync()
methods.
The given AsyncListener will receive an AsyncEvent
when
the asynchronous cycle completes successfully, times out, results
in an error, or a new asynchronous cycle is being initiated via
one of the ServletRequest.startAsync()
methods.
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
getSuppliedRequest
and
getSuppliedResponse
methods,
respectively, of the 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.
listener
- the AsyncListener to be registeredservletRequest
- the ServletRequest that will be included
in the AsyncEventservletResponse
- the ServletResponse that will be included
in the AsyncEventIllegalStateException
- if this method is called after
the container-initiated dispatch, during which one of the
ServletRequest.startAsync()
methods was called, has
returned to the container<T extends AsyncListener> T createListener(Class<T> clazz) throws ServletException
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.
clazz
- the AsyncListener class to instantiateServletException
- if the given clazz fails to be
instantiatedvoid setTimeout(long timeout)
The timeout applies to this AsyncContext once the
container-initiated dispatch during which one of the
ServletRequest.startAsync()
methods was called has
returned to the container.
The timeout will expire if neither the complete()
method
nor any of the dispatch methods are called. A timeout value of
zero or less indicates no timeout.
If setTimeout(long)
is not called, then the container's
default timeout, which is available via a call to
getTimeout()
, will apply.
The default value is 30000
ms.
timeout
- the timeout in millisecondsIllegalStateException
- if this method is called after
the container-initiated dispatch, during which one of the
ServletRequest.startAsync()
methods was called, has
returned to the containerlong getTimeout()
This method returns the container's default timeout for
asynchronous operations, or the timeout value passed to the most
recent invocation of setTimeout(long)
.
A timeout value of zero or less indicates no timeout.
Copyright © 2017 JBoss by Red Hat. All rights reserved.