com.levigo.jadice.appbase.reader

Class CancelableReaderTask<R>

java.lang.Object

com.levigo.jadice.appbase.reader.CancelableReaderTask<R>

Type Parameters:

R - the type of result returned by this task

All Implemented Interfaces:

Callable<R>, CancelableTask<R>, Task<R>

public abstract class CancelableReaderTask<R>
extends Object
implements CancelableTask<R>

Encapsulates a Reader and passes cancelation requests on to it in a thread-safe manner. The actual reading must be performed by subclasses implementing the template method(s).

Constructor Summary

Constructors

Constructor and Description
CancelableReaderTask()

Method Summary

Modifier and Type	Method and Description
R	call()
void	cancel()
protected Reader	createReader() Creates the Reader to be used by this task.
protected R	createReturnValue(Reader reader) Creates the result to be returned by this task.
protected void	didCancel() Invoked after cancelation has happened to give subclasses a chance to perform clean-up tasks.
protected abstract void	performRead(Reader reader) Template method to perform this task's workload.
protected void	willCancel() Invoked before cancelation happens to give subclasses a chance to perform clean-up tasks.

Methods inherited from class java.lang.Object

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

Constructor Detail

CancelableReaderTask

public CancelableReaderTask()

Method Detail

call

public final R call()
             throws Exception

Specified by:

call in interface Callable<R>

Throws:

Exception

createReader

protected Reader createReader()

Creates the Reader to be used by this task.

Returns:

a new instance of Reader

performRead

protected abstract void performRead(Reader reader)
                             throws Exception

Template method to perform this task's workload. This typically means reading data using the given Reader.

Parameters:

reader - the Reader used by this task

Throws:

Exception

createReturnValue

protected R createReturnValue(Reader reader)
                       throws Exception

Creates the result to be returned by this task.

Parameters:

reader - the Reader used by this task

Returns:

The default implementation returns null.

Throws:

Exception

cancel

public final void cancel()

Specified by:

cancel in interface CancelableTask<R>

willCancel

protected void willCancel()

Invoked before cancelation happens to give subclasses a chance to perform clean-up tasks.

didCancel

protected void didCancel()

Invoked after cancelation has happened to give subclasses a chance to perform clean-up tasks.