org.openstreetmap.josm.actions.downloadtasks
Interface DownloadTask

All Known Implementing Classes:

AbstractDownloadTask, DownloadGpsTask, DownloadOsmChangeCompressedTask, DownloadOsmChangeTask, DownloadOsmCompressedTask, DownloadOsmTask, DownloadOsmUrlTask

public interface DownloadTask

Interface defining a general download task used to download geographic data (OSM data, GPX tracks, etc.) for a given URL or geographic area.

Method Summary

boolean	acceptsUrl(java.lang.String url) Returns true if the task is able to open the given URL, false otherwise.
void	cancel() Cancels the asynchronous download task.
java.util.concurrent.Future<?>	download(boolean newLayer, Bounds downloadArea, ProgressMonitor progressMonitor) Asynchronously launches the download task for a given bounding box.
java.util.List<java.lang.Object>	getErrorObjects() Replies the error objects of the task.
java.util.concurrent.Future<?>	loadUrl(boolean newLayer, java.lang.String url, ProgressMonitor progressMonitor) Asynchronously launches the download task for a given bounding URL.

Method Detail

download

java.util.concurrent.Future<?> download(boolean newLayer,
                                        Bounds downloadArea,
                                        ProgressMonitor progressMonitor)

Asynchronously launches the download task for a given bounding box. Set progressMonitor to null, if the task should create, open, and close a progress monitor. Set progressMonitor to NullProgressMonitor.INSTANCE if progress information is to be discarded. You can wait for the asynchronous download task to finish by synchronizing on the returned Future, but make sure not to freeze up JOSM. Example:

    Future future = task.download(...);
    // DON'T run this on the Swing EDT or JOSM will freeze
    future.get(); // waits for the dowload task to complete
 

The following example uses a pattern which is better suited if a task is launched from the Swing EDT:

    final Future future = task.download(...);
    Runnable runAfterTask = new Runnable() {
       public void run() {
           // this is not strictly necessary because of the type of executor service
           // Main.worker is initialized with, but it doesn't harm either
           //
           future.get(); // wait for the download task to complete
           doSomethingAfterTheTaskCompleted();
       }
    }
    Main.worker.submit(runAfterTask);
 

Parameters:

newLayer - true, if the data is to be downloaded into a new layer. If false, the task selects one of the existing layers as download layer, preferably the active layer.

downloadArea - the area to download

progressMonitor - the progressMonitor

Returns:

the future representing the asynchronous task

loadUrl

java.util.concurrent.Future<?> loadUrl(boolean newLayer,
                                       java.lang.String url,
                                       ProgressMonitor progressMonitor)

Asynchronously launches the download task for a given bounding URL. Set progressMonitor to null, if the task should create, open, and close a progress monitor. Set progressMonitor to NullProgressMonitor.INSTANCE if progress information is to be discarded.

Parameters:

newLayer - newLayer true, if the data is to be downloaded into a new layer. If false, the task selects one of the existing layers as download layer, preferably the active layer.

url - the url to download from

progressMonitor - the progressMonitor

Returns:

the future representing the asynchronous task

See Also:

download(boolean, Bounds, ProgressMonitor)

acceptsUrl

boolean acceptsUrl(java.lang.String url)

Returns true if the task is able to open the given URL, false otherwise.

Parameters:

url - the url to download from

Returns:

True if the task is able to open the given URL, false otherwise.

getErrorObjects

java.util.List<java.lang.Object> getErrorObjects()

Replies the error objects of the task. Empty list, if no error messages are available. Error objects are either Strings with error messages or Exceptions.

Returns:

the list of error objects

cancel

void cancel()

Cancels the asynchronous download task.