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java.lang.Object org.zkoss.zkplus.util.ThreadLocalListener
public class ThreadLocalListener
Listener to make sure servlet thread and ZK event thread got the same ThreadLocal values. You have to declare this listener in WEB-INF/zk.xml as follows.
<listener>
<description>ThreadLocal Synchronization Listener</description>
<listener-class>org.zkoss.zkplus.util.ThreadLocalListener</listener-class>
</listener>
Besides that, you have to specify what ThreadLocal variables you want to sync. They are also specified in WEB-INF/zk.xml file in the form as below.
<preference>
<name>ThreadLocal</name>
<value>
class1=field1,field2,...;
class2=field1,field2,...;
...
</value>
</preference>
For example, to support synchronizing Spring's thread bounded resources, you have to specify the following ThreadLocal variables:
<preference>
<name>ThreadLocal</name>
<value>
org.springframework.transaction.support.TransactionSynchronizationManager=resources,synchronizations,currentTransactionName,currentTransactionReadOnly,actualTransactionActive;
org.springframework.orm.hibernate3.SessionFactoryUtils=deferredCloseHolder;
org.springframework.transaction.interceptor.TransactionAspectSupport=transactionInfoHolder; <!-- ver. 2+ -->
<!--org.springframework.transaction.interceptor.TransactionAspectSupport=currentTransactionInfo; ver. 1.28 -->
</value>
</preference>
In additions to using the application preference, you can specify it
in the library property called zkplus.util.ThreadLocalListener.fieldsMap
.
The preference has the higher priority.
Another example, when you specify the Spring's bean as scope="session", you have to specify the following
ThreadLocal variables since Spring 2.0 use RequestContextHolder to handle the bean's scope.
<preference>
<name>ThreadLocal</name>
<value>
org.springframework.web.context.request.RequestContextHolder=requestAttributesHolder,inheritableRequestAttributesHolder;
</value>
- Since:
- 2.4.1
- Author:
- henrichen
Constructor Summary
ThreadLocalListener()
Method Summary
void
abortResume(Component comp,
Event evt)
Called when the suspended event thread is aborted.
void
afterResume(Component comp,
Event evt)
Called after the suspended event thread is resumed.
void
beforeResume(Component comp,
Event evt)
Called just before the suspended event thread is resumed.
void
cleanup(Component comp,
Event evt,
java.util.List errs)
Cleans up the event processing thread.
void
complete(Component comp,
Event evt)
Called in the serlvet thread to clean up.
boolean
init(Component comp,
Event evt)
Initialize the event processing thread before processing the event.
void
prepare(Component comp,
Event evt)
Prepares the initialization at the servlet thread.
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Constructor Detail
ThreadLocalListener
public ThreadLocalListener()
Method Detail
prepare
public void prepare(Component comp,
Event evt)
- Description copied from interface:
EventThreadInit
- Prepares the initialization at the servlet thread.
It is invoked in the servlet thread (and before EventThreadInit.init(org.zkoss.zk.ui.Component, org.zkoss.zk.ui.event.Event)
).
Thus, you can NOT manipulate the desktop in this method.
If this method throws an exception, it will abort the execution
and shows an error message to the end user.
Note: EventThreadCleanup.cleanup(org.zkoss.zk.ui.Component, org.zkoss.zk.ui.event.Event, java.util.List)
won't be called if an
exception is thrown in this method, since it executes in
the main thread.
In addition to throwing an exception, you can prevent an event
from processing by returning false in EventThreadInit.init(org.zkoss.zk.ui.Component, org.zkoss.zk.ui.event.Event)
.
The event is ignored 'silently' then.
- Specified by:
prepare
in interface EventThreadInit
init
public boolean init(Component comp,
Event evt)
- Description copied from interface:
EventThreadInit
- Initialize the event processing thread before processing the event.
The simplest form is
void init(Component c, Event e) {return true;}
Unlike EventThreadInit.prepare(org.zkoss.zk.ui.Component, org.zkoss.zk.ui.event.Event)
, it is invoked in the event processing
thread (and after EventThreadInit.prepare(org.zkoss.zk.ui.Component, org.zkoss.zk.ui.event.Event)
).
Thus, you can manipulate the desktop in this method such as
creating a component.
If you want to prevent an event from processing, you can return
false in this method.
For example, you might create a highlighted window and return false
to prevent the user from accessing, if the system is too busy.
If the use of the event thread is disabled
(Configuration.isEventThreadEnabled()
returns false), this method is also invoked in the Servlet thread.
If this method throws an exception, it will abort the execution
and shows an error message to the end user (unless it is cleaned
up by EventThreadCleanup.cleanup(org.zkoss.zk.ui.Component, org.zkoss.zk.ui.event.Event, java.util.List)
).
- Specified by:
init
in interface EventThreadInit
- Returns:
- if it is initialized successfully.
If false is returned, the event is ignored, i.e., no event
handler/listener will be invoked.
cleanup
public void cleanup(Component comp,
Event evt,
java.util.List errs)
- Description copied from interface:
EventThreadCleanup
- Cleans up the event processing thread.
It is called, after a event processing thread has processed an event.
If this method threw an exception and errs is empty, the exception will
be propagated back to the servlet thread and then reported to the user.
Note: EventThreadCleanup.cleanup(org.zkoss.zk.ui.Component, org.zkoss.zk.ui.event.Event, java.util.List)
is called first in the event processing thread,
and then EventThreadCleanup.complete(org.zkoss.zk.ui.Component, org.zkoss.zk.ui.event.Event)
is called in the servlet thread.
Note: EventThreadCleanup.complete(org.zkoss.zk.ui.Component, org.zkoss.zk.ui.event.Event)
of an EventThreadCleanup
instance is called
only if EventThreadCleanup.cleanup(org.zkoss.zk.ui.Component, org.zkoss.zk.ui.event.Event, java.util.List)
called against the same instance
didn't throw any exception.
If the use of the event thread is disabled
(Configuration.isEventThreadEnabled()
returns false), this method is also invoked in the Servlet thread.
- Specified by:
cleanup
in interface EventThreadCleanup
errs
- a list of exceptions (java.lang.Throwable) if any exception
occurred before this method is called, or null if no exception at all.
Note: you can manipulate the list directly to add or clean up exceptions.
For example, if exceptions are fixed correctly, you can call errs.clear()
such that no error message will be displayed at the client.
complete
public void complete(Component comp,
Event evt)
- Description copied from interface:
EventThreadCleanup
- Called in the serlvet thread to clean up.
It is called after
EventThreadCleanup.cleanup(org.zkoss.zk.ui.Component, org.zkoss.zk.ui.event.Event, java.util.List)
is called.
Note: EventThreadCleanup.cleanup(org.zkoss.zk.ui.Component, org.zkoss.zk.ui.event.Event, java.util.List)
is called first in the event processing thread,
and then EventThreadCleanup.complete(org.zkoss.zk.ui.Component, org.zkoss.zk.ui.event.Event)
is called in the servlet thread.
- Specified by:
complete
in interface EventThreadCleanup
beforeResume
public void beforeResume(Component comp,
Event evt)
- Description copied from interface:
EventThreadResume
- Called just before the suspended event thread is resumed.
Unlike
EventThreadResume.afterResume(org.zkoss.zk.ui.Component, org.zkoss.zk.ui.event.Event)
, it executes in the main thread that
resumes the suspended event processing thread.
If this method throws an exception, it will abort the execution
and shows an error message to the end user.
Note: EventThreadCleanup.cleanup(org.zkoss.zk.ui.Component, org.zkoss.zk.ui.event.Event, java.util.List)
won't be called if an
exception is thrown in this method, since it executes in
the main thread.
- Specified by:
beforeResume
in interface EventThreadResume
afterResume
public void afterResume(Component comp,
Event evt)
- Description copied from interface:
EventThreadResume
- Called after the suspended event thread is resumed.
Unlike
EventThreadResume.beforeResume(org.zkoss.zk.ui.Component, org.zkoss.zk.ui.event.Event)
, it executes in the
event processing thread that is resumed.
If this method throws an exception, it will abort the execution
and shows an error message to the end user (unless it is cleaned
up by EventThreadCleanup.cleanup(org.zkoss.zk.ui.Component, org.zkoss.zk.ui.event.Event, java.util.List)
).
- Specified by:
afterResume
in interface EventThreadResume
abortResume
public void abortResume(Component comp,
Event evt)
- Description copied from interface:
EventThreadResume
- Called when the suspended event thread is aborted.
It is called in the main thread (i.e., the servlet thread).
If a suspended event thread is resumed normally, EventThreadResume.beforeResume(org.zkoss.zk.ui.Component, org.zkoss.zk.ui.event.Event)
and EventThreadResume.afterResume(org.zkoss.zk.ui.Component, org.zkoss.zk.ui.event.Event)
are called.
On the other hand, if it is aborted (usually caused by destroying
the desktop that owns this thread), EventThreadResume.abortResume(org.zkoss.zk.ui.Component, org.zkoss.zk.ui.event.Event)
is called instead.
Note: if the suspended thread is aborted, none of EventThreadResume.beforeResume(org.zkoss.zk.ui.Component, org.zkoss.zk.ui.event.Event)
,
EventThreadResume.afterResume(org.zkoss.zk.ui.Component, org.zkoss.zk.ui.event.Event)
, EventThreadCleanup.cleanup(org.zkoss.zk.ui.Component, org.zkoss.zk.ui.event.Event, java.util.List)
, and
EventThreadCleanup.complete(org.zkoss.zk.ui.Component, org.zkoss.zk.ui.event.Event)
will be called.
Thus, you have to do necessary cleanups in this method.
- Specified by:
abortResume
in interface EventThreadResume
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