EDU.oswego.cs.dl.util.concurrent.misc
public abstract class SwingWorker extends ThreadFactoryUser implements java.lang.Runnable
This class was adapted from the SwingWorker written by Hans Muller and presented in "Using a Swing Worker Thread" in the Swing Connection - http://java.sun.com/products/jfc/tsc/articles/threads/threads2.html
A closely related version of this class is described in "The Last Word in Swing Threads" in the Swing Connection - http://java.sun.com/products/jfc/tsc/articles/threads/threads3.html
This SwingWorker is a ThreadFactoryUser and implements Runnable. The default thread factory creates low-priority worker threads. A special constructor is provided for enabling a timeout. When the timeout expires, the worker thread is interrupted.
Note: Using a timeout of Long.MAX_VALUE
will not impose a
timeout but will create an additional thread of control that will respond
to an interrupt even if the construct
implementation ignores
them.
Sample Usage
import EDU.oswego.cs.dl.util.concurrent.TimeoutException; import EDU.oswego.cs.dl.util.concurrent.misc.SwingWorker; public class SwingWorkerDemo extends javax.swing.JApplet { private static final int TIMEOUT = 5000; // 5 seconds private javax.swing.JLabel status; private javax.swing.JButton start; private SwingWorker worker; public SwingWorkerDemo() { status = new javax.swing.JLabel("Ready"); status.setHorizontalAlignment(javax.swing.SwingConstants.CENTER); getContentPane().add(status, java.awt.BorderLayout.CENTER); start = new javax.swing.JButton("Start"); getContentPane().add(start, java.awt.BorderLayout.SOUTH); start.addActionListener(new java.awt.event.ActionListener() { public void actionPerformed(java.awt.event.ActionEvent evt) { if (start.getText().equals("Start")) { start.setText("Stop"); status.setText("Working..."); worker = new DemoSwingWorker(TIMEOUT); worker.start(); } else { worker.interrupt(); } } }); } private class DemoSwingWorker extends SwingWorker { private static final java.util.Random RAND = new java.util.Random(); public DemoSwingWorker(long msecs) { super(msecs); } protected Object construct() throws InterruptedException { // Take a random nap. If we oversleep, the worker times out. Thread.sleep(RAND.nextInt(2*TIMEOUT)); return "Success"; } protected void finished() { start.setText("Start"); try { Object result = get(); status.setText((String) result); } catch (java.lang.reflect.InvocationTargetException e) { Throwable ex = e.getTargetException(); if (ex instanceof TimeoutException) { status.setText("Timed out."); } else if (ex instanceof InterruptedException) { status.setText("Interrupted."); } else { status.setText("Exception: " + ex); } } catch (InterruptedException ex) { // event-dispatch thread won't be interrupted throw new IllegalStateException(ex+""); } } } }
ThreadFactoryUser.DefaultThreadFactory
threadFactory_
Modifier | Constructor and Description |
---|---|
|
SwingWorker()
Creates new SwingWorker with no timeout.
|
|
SwingWorker(long msecs)
Creates new SwingWorker with specified timeout.
|
protected |
SwingWorker(ThreadFactory factory,
long msecs)
Creates new SwingWorker with specified thread factory and timeout.
|
Modifier and Type | Method and Description |
---|---|
protected abstract java.lang.Object |
construct()
Computes the value to be returned by the
get method. |
protected void |
finished()
Called on the event dispatching thread (not on the worker thread)
after the
construct method has returned. |
java.lang.Object |
get()
Return the value created by the
construct method,
waiting if necessary until it is ready. |
java.lang.reflect.InvocationTargetException |
getException()
Get the exception, or null if there isn't one (yet).
|
long |
getTimeout()
Returns timeout period in milliseconds.
|
void |
interrupt()
Stops the worker and sets the exception to InterruptedException.
|
boolean |
isReady()
Return whether the
get method is ready to
return a value. |
void |
run()
Calls the
construct method to compute the result,
and then invokes the finished method on the event
dispatch thread. |
void |
start()
Starts the worker thread.
|
java.lang.Object |
timedGet(long msecs)
Wait at most msecs to access the constructed result.
|
getThreadFactory, setThreadFactory
public SwingWorker()
public SwingWorker(long msecs)
msecs
- timeout in milliseconds, or 0
for no time limit.protected SwingWorker(ThreadFactory factory, long msecs)
factory
- factory for worker threads.msecs
- timeout in milliseconds, or 0
for no time limit.protected abstract java.lang.Object construct() throws java.lang.Exception
get
method.java.lang.Exception
protected void finished()
construct
method has returned.public long getTimeout()
0
(default).public void run()
construct
method to compute the result,
and then invokes the finished
method on the event
dispatch thread.run
in interface java.lang.Runnable
public void start()
public void interrupt()
public java.lang.Object get() throws java.lang.InterruptedException, java.lang.reflect.InvocationTargetException
construct
method,
waiting if necessary until it is ready.construct
methodjava.lang.InterruptedException
- if current thread was interruptedjava.lang.reflect.InvocationTargetException
- if the constructing thread
encountered an exception or was interrupted.public java.lang.Object timedGet(long msecs) throws TimeoutException, java.lang.InterruptedException, java.lang.reflect.InvocationTargetException
TimeoutException
- if not ready after msecsjava.lang.InterruptedException
- if current thread has been interruptedjava.lang.reflect.InvocationTargetException
- if the constructing thread
encountered an exception or was interrupted.public java.lang.reflect.InvocationTargetException getException()
construct
method wrapped in an InvocationTargetExceptionpublic boolean isReady()
get
method is ready to
return a value.