FactoryBean that sets up
(by default: a ScheduledThreadPoolExecutor)
and exposes it for bean references.
Allows for registration of ScheduledExecutorTasks,
automatically starting the ScheduledExecutorService on initialization and
cancelling it on destruction of the context. In scenarios that only require static
registration of tasks at startup, there is no need to access the
ScheduledExecutorService instance itself in application code at all;
ScheduledExecutorFactoryBean is then just being used for lifecycle integration.
For an alternative, you may set up a ScheduledThreadPoolExecutor instance
directly using constructor injection, or use a factory method definition that points
to the Executors class.
This is strongly recommended in particular for common @Bean methods in
configuration classes, where this FactoryBean variant would force you to
return the FactoryBean type instead of ScheduledExecutorService.
Note that ScheduledExecutorService
uses a Runnable instance that is shared between repeated executions,
in contrast to Quartz which instantiates a new Job for each execution.
WARNING:Runnables submitted via a native
ScheduledExecutorService are removed from
the execution schedule once they throw an exception. If you would prefer
to continue execution after such an exception, switch this FactoryBean's
property to "true".
Register a list of ScheduledExecutorTask objects with the ScheduledExecutorService
that this FactoryBean creates. Depending on each ScheduledExecutorTask's settings,
it will be registered via one of ScheduledExecutorService's schedule methods.
public void setRemoveOnCancelPolicy(boolean removeOnCancelPolicy)
Set the remove-on-cancel mode on ScheduledThreadPoolExecutor.
Default is false. If set to true, the target executor will be
switched into remove-on-cancel mode (if possible, with a soft fallback otherwise).
public void setContinueScheduledExecutionAfterException(boolean continueScheduledExecutionAfterException)
Specify whether to continue the execution of a scheduled task
after it threw an exception.
Default is "false", matching the native behavior of a
Switch this flag to "true" for exception-proof execution of each task,
continuing scheduled execution as in the case of successful execution.
Return an instance (possibly shared or independent) of the object
managed by this factory.
As with a BeanFactory, this allows support for both the
Singleton and Prototype design pattern.
If this FactoryBean is not fully initialized yet at the time of
the call (for example because it is involved in a circular reference),
throw a corresponding FactoryBeanNotInitializedException.
As of Spring 2.0, FactoryBeans are allowed to return null
objects. The factory will consider this as normal value to be used; it
will not throw a FactoryBeanNotInitializedException in this case anymore.
FactoryBean implementations are encouraged to throw
FactoryBeanNotInitializedException themselves now, as appropriate.
Return the type of object that this FactoryBean creates,
or null if not known in advance.
This allows one to check for specific types of beans without
instantiating objects, for example on autowiring.
In the case of implementations that are creating a singleton object,
this method should try to avoid singleton creation as far as possible;
it should rather estimate the type in advance.
For prototypes, returning a meaningful type here is advisable too.
This method can be called before this FactoryBean has
been fully initialized. It must not rely on state created during
initialization; of course, it can still use such state if available.
NOTE: Autowiring will simply ignore FactoryBeans that return
null here. Therefore it is highly recommended to implement
this method properly, using the current state of the FactoryBean.
Is the object managed by this factory a singleton? That is,
will FactoryBean.getObject() always return the same object
(a reference that can be cached)?
NOTE: If a FactoryBean indicates to hold a singleton object,
the object returned from getObject() might get cached
by the owning BeanFactory. Hence, do not return true
unless the FactoryBean always exposes the same reference.
The singleton status of the FactoryBean itself will generally
be provided by the owning BeanFactory; usually, it has to be
defined as singleton there.
NOTE: This method returning false does not
necessarily indicate that returned objects are independent instances.
An implementation of the extended SmartFactoryBean interface
may explicitly indicate independent instances through its
SmartFactoryBean.isPrototype() method. Plain FactoryBean
implementations which do not implement this extended interface are
simply assumed to always return independent instances if the
isSingleton() implementation returns false.
The default implementation returns true, since a
FactoryBean typically manages a singleton instance.