我正在使用媒体播放器应用程序。我正在使用exoplayer库。我有一个视频播放列表，我想同时下载视频。我通过在GitHub上使用Exoplayer库的可用演示应用来完成。我想在UI中显示每个下载的进度。对于这项工作，我从DownloadNotificationUtil.buildProgressNotification方法获得帮助。
@Override
protected Notification getForegroundNotification(TaskState[] taskStates) {
float totalPercentage = 0;
int downloadTaskCount = 0;
boolean allDownloadPercentagesUnknown = true;
boolean haveDownloadedBytes = false;
boolean haveDownloadTasks = false;
boolean haveRemoveTasks = false;
Log.e(TAG,"size task state: "+taskStates.length);
for (TaskState taskState : taskStates) {
Log.e(TAG,"taskId= "+taskState.taskId);
if (taskState.state != TaskState.STATE_STARTED
&& taskState.state != TaskState.STATE_COMPLETED) {
continue;
}
if (taskState.action.isRemoveAction) {
haveRemoveTasks = true;
continue;
}
haveDownloadTasks = true;
if (taskState.downloadPercentage != C.PERCENTAGE_UNSET) {
allDownloadPercentagesUnknown = false;
totalPercentage += taskState.downloadPercentage;
}
haveDownloadedBytes |= taskState.downloadedBytes > 0;
downloadTaskCount++;
}
int progress = 0;
boolean indeterminate = true;
if (haveDownloadTasks) {
progress = (int) (totalPercentage / downloadTaskCount);
indeterminate = allDownloadPercentagesUnknown && haveDownloadedBytes;
Log.e(TAG,"notifi "+progress);
}
return DownloadNotificationUtil.buildProgressNotification(
this,
R.drawable.exo_icon_play,
DOWNLOAD_CHANNEL_ID,
null,
null,
taskStates);
}
现在，我可以跟踪进度下载。但是我仍然有问题。我不明白哪个项目正在下载以更新UI中的进度栏。每个下载都有相同的ID来识别它吗？例如，Android Download Manager为每个下载文件都有一个下载ID。但是我不知道，如何解决这个问题。这是MediaDownloadService：
public class MediaDownloadService extends DownloadService {
public static String TAG="MediaDownloadService";
private static final int FOREGROUND_NOTIFICATION_ID = 1;
public MediaDownloadService() {
super(
DOWNLOAD_NOTIFICATION_ID,
DEFAULT_FOREGROUND_NOTIFICATION_UPDATE_INTERVAL,
DOWNLOAD_CHANNEL_ID,
R.string.download_channel_name);
}
@Override
protected DownloadManager getDownloadManager() {
return ((MyApplication) getApplication()).getDownloadManager();
}
@Nullable
@Override
protected Scheduler getScheduler() {
return null;
}
@Override
protected Notification getForegroundNotification(TaskState[] taskStates) {
float totalPercentage = 0;
int downloadTaskCount = 0;
boolean allDownloadPercentagesUnknown = true;
boolean haveDownloadedBytes = false;
boolean haveDownloadTasks = false;
boolean haveRemoveTasks = false;
for (TaskState taskState : taskStates) {
if (taskState.state != TaskState.STATE_STARTED
&& taskState.state != TaskState.STATE_COMPLETED) {
continue;
}
if (taskState.action.isRemoveAction) {
haveRemoveTasks = true;
continue;
}
haveDownloadTasks = true;
if (taskState.downloadPercentage != C.PERCENTAGE_UNSET) {
allDownloadPercentagesUnknown = false;
totalPercentage += taskState.downloadPercentage;
}
haveDownloadedBytes |= taskState.downloadedBytes > 0;
downloadTaskCount++;
}
int progress = 0;
boolean indeterminate = true;
if (haveDownloadTasks) {
progress = (int) (totalPercentage / downloadTaskCount);
indeterminate = allDownloadPercentagesUnknown && haveDownloadedBytes;
Log.e(TAG,"notifi "+progress);
sendIntent(progress);
}
return DownloadNotificationUtil.buildProgressNotification(
this,
R.drawable.exo_icon_play,
DOWNLOAD_CHANNEL_ID,
null,
null,
taskStates);
}
private void sendIntent(int progress){
Intent intent = new Intent(ConstantUtil.MESSAGE_PROGRESS);
intent.putExtra("progress",progress);
LocalBroadcastManager.getInstance(MediaDownloadService.this).sendBroadcast(intent);
}
@Override
protected void onTaskStateChanged(TaskState taskState) {
if (taskState.action.isRemoveAction) {
return;
}
Notification notification = null;
if (taskState.state == TaskState.STATE_COMPLETED) {
Log.e(TAG,"STATE_COMPLETED");
notification =
DownloadNotificationUtil.buildDownloadCompletedNotification(
/* context= */ this,
R.drawable.exo_controls_play,
DOWNLOAD_CHANNEL_ID,
/* contentIntent= */ null,
Util.fromUtf8Bytes(taskState.action.data));
} else if (taskState.state == TaskState.STATE_FAILED) {
Log.e(TAG,"STATE_FAILED");
notification =
DownloadNotificationUtil.buildDownloadFailedNotification(
/* context= */ this,
R.drawable.exo_controls_play,
DOWNLOAD_CHANNEL_ID,
/* contentIntent= */ null,
Util.fromUtf8Bytes(taskState.action.data));
}
int notificationId = FOREGROUND_NOTIFICATION_ID + 1 + taskState.taskId;
NotificationUtil.setNotification(this, notificationId, notification);
}
}
这是DownloadTracker类：
public class DownloadTracker implements DownloadManager.Listener {
/** Listens for changes in the tracked downloads. */
public interface Listener {
/** Called when the tracked downloads changed. */
void onDownloadsChanged();
}
private static final String TAG = "DownloadTracker";
private final Context context;
private final DataSource.Factory dataSourceFactory;
private final TrackNameProvider trackNameProvider;
private final CopyOnWriteArraySet<Listener> listeners;
private Listener onDownloadsChanged;
private final HashMap<Uri, DownloadAction> trackedDownloadStates;
private final ActionFile actionFile;
private final Handler actionFileWriteHandler;
public DownloadTracker(
Context context,
DataSource.Factory dataSourceFactory,
File actionFile,
DownloadAction.Deserializer... deserializers) {
this.context = context.getApplicationContext();
this.dataSourceFactory = dataSourceFactory;
this.actionFile = new ActionFile(actionFile);
trackNameProvider = new DefaultTrackNameProvider(context.getResources());
listeners = new CopyOnWriteArraySet<>();
trackedDownloadStates = new HashMap<>();
HandlerThread actionFileWriteThread = new HandlerThread("DownloadTracker");
actionFileWriteThread.start();
actionFileWriteHandler = new Handler(actionFileWriteThread.getLooper());
loadTrackedActions(
deserializers.length > 0 ? deserializers : DownloadAction.getDefaultDeserializers());
}
public void addListener(Listener listener) {
listeners.add(listener);
}
public void removeListener(Listener listener) {
listeners.remove(listener);
}
public boolean isDownloaded(Uri uri) {
return trackedDownloadStates.containsKey(uri);
}
@SuppressWarnings("unchecked")
public List<StreamKey> getOfflineStreamKeys(Uri uri) {
if (!trackedDownloadStates.containsKey(uri)) {
return Collections.emptyList();
}
return trackedDownloadStates.get(uri).getKeys();
}
public int toggleDownload(Activity activity, String name, Uri uri, String extension) {
if (isDownloaded(uri)) {
Log.e(TAG,"isDownloaded");
DownloadAction removeAction =
getDownloadHelper(uri, extension).getRemoveAction(Util.getUtf8Bytes(name));
startServiceWithAction(removeAction);
return -1;
} else {
StartDownloadDialogHelper helper =
new StartDownloadDialogHelper(activity, getDownloadHelper(uri, extension), name);
helper.prepare();
return helper.getTaskId();
}
}
@Override
public void onInitialized(DownloadManager downloadManager) {
// Do nothing.
}
@Override
public void onTaskStateChanged(DownloadManager downloadManager, TaskState taskState) {
DownloadAction action = taskState.action;
Uri uri = action.uri;
if ((action.isRemoveAction && taskState.state == TaskState.STATE_COMPLETED)
|| (!action.isRemoveAction && taskState.state == TaskState.STATE_FAILED)) {
// A download has been removed, or has failed. Stop tracking it.
if (trackedDownloadStates.remove(uri) != null) {
handleTrackedDownloadStatesChanged();
}
}
}
@Override
public void onIdle(DownloadManager downloadManager) {
// Do nothing.
}
// Internal methods
private void loadTrackedActions(DownloadAction.Deserializer[] deserializers) {
try {
DownloadAction[] allActions = actionFile.load(deserializers);
for (DownloadAction action : allActions) {
trackedDownloadStates.put(action.uri, action);
}
} catch (IOException e) {
Log.e(TAG, "Failed to load tracked actions", e);
}
}
private void handleTrackedDownloadStatesChanged() {
for (Listener listener : listeners) {
listener.onDownloadsChanged();
}
final DownloadAction[] actions = trackedDownloadStates.values().toArray(new DownloadAction[0]);
Log.e(TAG,"actions: "+actions.toString());
actionFileWriteHandler.post(
() -> {
try {
actionFile.store(actions);
} catch (IOException e) {
Log.e(TAG, "Failed to store tracked actions", e);
}
});
}
private void startDownload(DownloadAction action) {
if (trackedDownloadStates.containsKey(action.uri)) {
// This content is already being downloaded. Do nothing.
Log.e(TAG,"download already exsit");
return;
}
trackedDownloadStates.put(action.uri, action);
handleTrackedDownloadStatesChanged();
startServiceWithAction(action);
}
private void startServiceWithAction(DownloadAction action) {
DownloadService.startWithAction(context, MediaDownloadService.class, action, false);
}
private DownloadHelper getDownloadHelper(Uri uri, String extension) {
int type = Util.inferContentType(uri, extension);
switch (type) {
case C.TYPE_DASH:
return new DashDownloadHelper(uri, dataSourceFactory);
case C.TYPE_SS:
return new SsDownloadHelper(uri, dataSourceFactory);
case C.TYPE_HLS:
return new HlsDownloadHelper(uri, dataSourceFactory);
case C.TYPE_OTHER:
return new ProgressiveDownloadHelper(uri);
default:
throw new IllegalStateException("Unsupported type: " + type);
}
}
private final class StartDownloadDialogHelper
implements DownloadHelper.Callback, DialogInterface.OnClickListener {
private final DownloadHelper downloadHelper;
private final String name;
private final AlertDialog.Builder builder;
private final View dialogView;
private final List<TrackKey> trackKeys;
private final ArrayAdapter<String> trackTitles;
private final ListView representationList;
private int taskId;
public StartDownloadDialogHelper(
Activity activity, DownloadHelper downloadHelper, String name) {
this.downloadHelper = downloadHelper;
this.name = name;
builder =
new AlertDialog.Builder(activity)
.setTitle(R.string.exo_download_description)
.setPositiveButton(android.R.string.ok, this)
.setNegativeButton(android.R.string.cancel, null);
// Inflate with the builder's context to ensure the correct style is used.
LayoutInflater dialogInflater = LayoutInflater.from(builder.getContext());
dialogView = dialogInflater.inflate(R.layout.start_download_dialog, null);
trackKeys = new ArrayList<>();
trackTitles =
new ArrayAdapter<>(
builder.getContext(), android.R.layout.simple_list_item_multiple_choice);
representationList = dialogView.findViewById(R.id.representation_list);
representationList.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);
representationList.setAdapter(trackTitles);
}
public void prepare() {
downloadHelper.prepare(this);
}
@Override
public void onPrepared(DownloadHelper helper) {
for (int i = 0; i < downloadHelper.getPeriodCount(); i++) {
TrackGroupArray trackGroups = downloadHelper.getTrackGroups(i);
for (int j = 0; j < trackGroups.length; j++) {
TrackGroup trackGroup = trackGroups.get(j);
for (int k = 0; k < trackGroup.length; k++) {
trackKeys.add(new TrackKey(i, j, k));
trackTitles.add(trackNameProvider.getTrackName(trackGroup.getFormat(k)));
}
}
}
if (!trackKeys.isEmpty()) {
builder.setView(dialogView);
}
builder.create().show();
}
@Override
public void onPrepareError(DownloadHelper helper, IOException e) {
Toast.makeText(
context.getApplicationContext(), R.string.download_start_error, Toast.LENGTH_LONG)
.show();
Log.e(TAG, "Failed to start download", e);
}
@Override
public void onClick(DialogInterface dialog, int which) {
ArrayList<TrackKey> selectedTrackKeys = new ArrayList<>();
for (int i = 0; i < representationList.getChildCount(); i++) {
if (representationList.isItemChecked(i)) {
selectedTrackKeys.add(trackKeys.get(i));
}
}
if (!selectedTrackKeys.isEmpty() || trackKeys.isEmpty()) {
// We have selected keys, or we're dealing with single stream content.
DownloadAction downloadAction =
downloadHelper.getDownloadAction(Util.getUtf8Bytes(name), selectedTrackKeys);
taskId=MyApplication.getInstance().getDownloadManager().handleAction(downloadAction);
startDownload(downloadAction);
}
}
}
}
在我的片段/活动中：
/* this method will be called when user click on download button of each item */
@Override
public void onDownloadClick(LectureList lecture) {
Log.e(TAG,"onClickDownload");
downloadTracker.toggleDownload(this,lecture.getTitle_lecture(),
Uri.parse(lecture.getUrlPath()),lecture.getExtension());
}
这是我的广播接收器：
private BroadcastReceiver broadcastReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
Log.e(TAG,"onRecive download");
if(intent.getAction().equals(MESSAGE_PROGRESS)){
int progress=intent.getLongExtra("progress",0);
}
}
};
在 getforegroundNotification（）方法中，您将获得 taskState 对象的列表，该对象具有成员 downloadpercentage 和您的下载uri taskState.action.uri 对于每个下载任务都是唯一的。将这些变量存储到地图中并广播地图。
override fun getForegroundNotification(taskStates: Array<TaskState>): Notification {
var totalPercentage = 0f
var downloadTaskCount = 0
var progressMap : HashMap<Uri, Int> = HashMap()
for (taskState in taskStates) {
if (taskState.state != TaskState.STATE_STARTED && taskState.state != TaskState.STATE_COMPLETED) {
continue
}
if (taskState.action.isRemoveAction) {
continue
}
if (taskState.downloadPercentage != C.PERCENTAGE_UNSET.toFloat()) {
totalPercentage += taskState.downloadPercentage
progressMap.put(taskState.action.uri, taskState.downloadPercentage.toInt())
}
downloadTaskCount++
}
var progress = 0
progress = (totalPercentage / downloadTaskCount).toInt()
broadcastIndividualProgress(progressMap)
return buildProgressNotification(progress)
}