org.springframework.web.context.request.async

Class WebAsyncManager

java.lang.Object

org.springframework.web.context.request.async.WebAsyncManager

public final class WebAsyncManager
extends Object

The central class for managing asynchronous request processing, mainly intended as an SPI and not typically used directly by application classes.

An async scenario starts with request processing as usual in a thread (T1). Concurrent request handling can be initiated by calling startCallableProcessing or startDeferredResultProcessing, both of which produce a result in a separate thread (T2). The result is saved and the request dispatched to the container, to resume processing with the saved result in a third thread (T3). Within the dispatched thread (T3), the saved result can be accessed via getConcurrentResult() or its presence detected via hasConcurrentResult().

Since:

3.2

Author:

Rossen Stoyanchev, Juergen Hoeller, Sam Brannen

See Also:

AsyncWebRequestInterceptor, AsyncHandlerInterceptor, OncePerRequestFilter.shouldNotFilterAsyncDispatch(), OncePerRequestFilter.isAsyncDispatch(javax.servlet.http.HttpServletRequest)

Method Summary

Modifier and Type	Method and Description
void	clearConcurrentResult() Clear concurrentResult and concurrentResultContext.
CallableProcessingInterceptor	getCallableInterceptor(Object key) Get the CallableProcessingInterceptor registered under the given key.
Object	getConcurrentResult() Provides access to the result from concurrent handling.
Object[]	getConcurrentResultContext() Provides access to additional processing context saved at the start of concurrent handling.
DeferredResultProcessingInterceptor	getDeferredResultInterceptor(Object key) Get the DeferredResultProcessingInterceptor registered under the given key.
boolean	hasConcurrentResult() Whether a result value exists as a result of concurrent handling.
boolean	isConcurrentHandlingStarted() Whether the selected handler for the current request chose to handle the request asynchronously.
void	registerCallableInterceptor(Object key, CallableProcessingInterceptor interceptor) Register a CallableProcessingInterceptor under the given key.
void	registerCallableInterceptors(CallableProcessingInterceptor... interceptors) Register a CallableProcessingInterceptor without a key.
void	registerDeferredResultInterceptor(Object key, DeferredResultProcessingInterceptor interceptor) Register a DeferredResultProcessingInterceptor under the given key.
void	registerDeferredResultInterceptors(DeferredResultProcessingInterceptor... interceptors) Register one or more DeferredResultProcessingInterceptors without a specified key.
void	setAsyncWebRequest(AsyncWebRequest asyncWebRequest) Configure the AsyncWebRequest to use.
void	setTaskExecutor(AsyncTaskExecutor taskExecutor) Configure an AsyncTaskExecutor for use with concurrent processing via startCallableProcessing(Callable, Object...).
void	startCallableProcessing(Callable<?> callable, Object... processingContext) Start concurrent request processing and execute the given task with an AsyncTaskExecutor.
void	startCallableProcessing(WebAsyncTask<?> webAsyncTask, Object... processingContext) Use the given WebAsyncTask to configure the task executor as well as the timeout value of the AsyncWebRequest before delegating to startCallableProcessing(Callable, Object...).
void	startDeferredResultProcessing(DeferredResult<?> deferredResult, Object... processingContext) Start concurrent request processing and initialize the given DeferredResult with a DeferredResult.DeferredResultHandler that saves the result and dispatches the request to resume processing of that result.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

setAsyncWebRequest

public void setAsyncWebRequest(AsyncWebRequest asyncWebRequest)

Configure the AsyncWebRequest to use. This property may be set more than once during a single request to accurately reflect the current state of the request (e.g. following a forward, request/response wrapping, etc). However, it should not be set while concurrent handling is in progress, i.e. while isConcurrentHandlingStarted() is true.

Parameters:

asyncWebRequest - the web request to use

setTaskExecutor

public void setTaskExecutor(AsyncTaskExecutor taskExecutor)

Configure an AsyncTaskExecutor for use with concurrent processing via startCallableProcessing(Callable, Object...).

By default a SimpleAsyncTaskExecutor instance is used.

isConcurrentHandlingStarted

public boolean isConcurrentHandlingStarted()

Whether the selected handler for the current request chose to handle the request asynchronously. A return value of "true" indicates concurrent handling is under way and the response will remain open. A return value of "false" means concurrent handling was either not started or possibly that it has completed and the request was dispatched for further processing of the concurrent result.

hasConcurrentResult

public boolean hasConcurrentResult()

Whether a result value exists as a result of concurrent handling.

getConcurrentResult

@Nullable
public Object getConcurrentResult()

Provides access to the result from concurrent handling.

Returns:

an Object, possibly an Exception or Throwable if concurrent handling raised one.

See Also:

clearConcurrentResult()

getConcurrentResultContext

@Nullable
public Object[] getConcurrentResultContext()

Provides access to additional processing context saved at the start of concurrent handling.

See Also:

clearConcurrentResult()

getCallableInterceptor

@Nullable
public CallableProcessingInterceptor getCallableInterceptor(Object key)

Get the CallableProcessingInterceptor registered under the given key.

Parameters:

key - the key

Returns:

the interceptor registered under that key, or null if none

getDeferredResultInterceptor

@Nullable
public DeferredResultProcessingInterceptor getDeferredResultInterceptor(Object key)

Get the DeferredResultProcessingInterceptor registered under the given key.

Parameters:

key - the key

Returns:

the interceptor registered under that key, or null if none

registerCallableInterceptor

public void registerCallableInterceptor(Object key,
                                        CallableProcessingInterceptor interceptor)

Register a CallableProcessingInterceptor under the given key.

Parameters:

key - the key

interceptor - the interceptor to register

registerCallableInterceptors

public void registerCallableInterceptors(CallableProcessingInterceptor... interceptors)

Register a CallableProcessingInterceptor without a key. The key is derived from the class name and hashcode.

Parameters:

interceptors - one or more interceptors to register

registerDeferredResultInterceptor

public void registerDeferredResultInterceptor(Object key,
                                              DeferredResultProcessingInterceptor interceptor)

Register a DeferredResultProcessingInterceptor under the given key.

Parameters:

key - the key

interceptor - the interceptor to register

registerDeferredResultInterceptors

public void registerDeferredResultInterceptors(DeferredResultProcessingInterceptor... interceptors)

Register one or more DeferredResultProcessingInterceptors without a specified key. The default key is derived from the interceptor class name and hash code.

Parameters:

interceptors - one or more interceptors to register

clearConcurrentResult

public void clearConcurrentResult()

Clear concurrentResult and concurrentResultContext.

startCallableProcessing

public void startCallableProcessing(Callable<?> callable,
                                    Object... processingContext)
                             throws Exception

Start concurrent request processing and execute the given task with an AsyncTaskExecutor. The result from the task execution is saved and the request dispatched in order to resume processing of that result. If the task raises an Exception then the saved result will be the raised Exception.

Parameters:

callable - a unit of work to be executed asynchronously

processingContext - additional context to save that can be accessed via getConcurrentResultContext()

Throws:

Exception - if concurrent processing failed to start

See Also:

getConcurrentResult(), getConcurrentResultContext()

startCallableProcessing

public void startCallableProcessing(WebAsyncTask<?> webAsyncTask,
                                    Object... processingContext)
                             throws Exception

Use the given WebAsyncTask to configure the task executor as well as the timeout value of the AsyncWebRequest before delegating to startCallableProcessing(Callable, Object...).

Parameters:

webAsyncTask - a WebAsyncTask containing the target Callable

processingContext - additional context to save that can be accessed via getConcurrentResultContext()

Throws:

Exception - if concurrent processing failed to start

startDeferredResultProcessing

public void startDeferredResultProcessing(DeferredResult<?> deferredResult,
                                          Object... processingContext)
                                   throws Exception

Start concurrent request processing and initialize the given DeferredResult with a DeferredResult.DeferredResultHandler that saves the result and dispatches the request to resume processing of that result. The AsyncWebRequest is also updated with a completion handler that expires the DeferredResult and a timeout handler assuming the DeferredResult has a default timeout result.

Parameters:

deferredResult - the DeferredResult instance to initialize

processingContext - additional context to save that can be accessed via getConcurrentResultContext()

Throws:

Exception - if concurrent processing failed to start

See Also:

getConcurrentResult(), getConcurrentResultContext()