我一直在努力解决 SwingWorker 吃掉后台任务中抛出的任何异常的可用性问题,例如,在这个 SO thread 上描述的。该线程很好地描述了问题,但没有讨论恢复原始异常。
我收到的小程序需要向上传播异常。但我什至无法抓住它。我正在使用此博客条目中的 SimpleSwingWorker 包装类来专门尝试解决此问题。这是一个相当小的课程,但我会在最后重新发布它以供参考。
调用代码看起来很像
try {
// lots of code here to prepare data, finishing with
SpecialDataHelper helper = new SpecialDataHelper(...stuff...);
helper.execute(); // this will call get+done on the actual worker
} catch (Throwable e) {
// used "Throwable" here in desperation to try and get
// anything at all to match, including unchecked exceptions
//
// no luck, this code is never ever used :-(
}
包装:
class SpecialDataHelper extends SimpleSwingWorker {
public SpecialDataHelper (SpecialData sd) {
this.stuff = etc etc etc;
}
public Void doInBackground() throws Exception {
OurCodeThatThrowsACheckedException(this.stuff);
return null;
}
protected void done() {
// called only when successful
// never reached if there's an error
}
}
的特点SimpleSwingWorker
是会自动调用实际的 SwingWorkerdone()/get()
方法。从理论上讲,这会重新引发后台发生的任何异常。在实践中,什么都没有被抓到,我什至不知道为什么。
SimpleSwingWorker 类,供参考,为简洁起见,没有省略:
import java.util.concurrent.ExecutionException;
import javax.swing.SwingWorker;
/**
* A drop-in replacement for SwingWorker<Void,Void> but will not silently
* swallow exceptions during background execution.
*
* Taken from http://jonathangiles.net/blog/?p=341 with thanks.
*/
public abstract class SimpleSwingWorker {
private final SwingWorker<Void,Void> worker =
new SwingWorker<Void,Void>() {
@Override
protected Void doInBackground() throws Exception {
SimpleSwingWorker.this.doInBackground();
return null;
}
@Override
protected void done() {
// Exceptions are lost unless get() is called on the
// originating thread. We do so here.
try {
get();
} catch (final InterruptedException ex) {
throw new RuntimeException(ex);
} catch (final ExecutionException ex) {
throw new RuntimeException(ex.getCause());
}
SimpleSwingWorker.this.done();
}
};
public SimpleSwingWorker() {}
protected abstract Void doInBackground() throws Exception;
protected abstract void done();
public void execute() {
worker.execute();
}
}