Downloadmanager in android
16lz
2021-12-04
Downloadmanager使用
DownloadManager是android提供的一个下载管理器
缺点:不支持断点续传
使用方法:
创建实例:
DownloadManager manager = (DownloadManager) context.getSystemService(Context.DOWNLOAD_SERVICE);
创建下载任务:
DownloadManager.Request request = new DownloadManager.Request(Uri.parse(URL));//指定保存地址request.setDestinationInExternalPublicDir("chuyi", "meizhi.apk");//设置允许下载的网络状况request.setAllowedNetworkTypes(DownloadManager.Request.NETWORK_WIFI);//设置通知栏的行为request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);//通过id唯一标识此下载任务long id = manager.enqueue(request);
删除下载任务:
manager.remove(id);
查询下载任务:
DownloadManager.Query query = new DownloadManager.Query();query.setFilterById(id);Cursor cursor = manager.query(query);if(cursor.moveToFirst()){ String filename = cursor.getString(cursor.getColumnIndex(DownloadManager.COLUMN_LOCAL_FILENAME)); String fileUri = cursor.getString(cursor.getColumnIndex(DownloadManager.COLUMN_LOCAL_URI)); Toast.makeText(context,"下载完成...name:"+filename+",uri:"+fileUri,Toast.LENGTH_SHORT).show();}else { //TODO}cursor.close();
查询下载进度:
DownloadManager.Query query = new DownloadManager.Query().setFilterById(downloadId);Cursor c = null;try { c = downloadManager.query(query); if (c != null && c.moveToFirst()) { int downloadedBytes = c.getInt(c.getColumnIndexOrThrow(DownloadManager.COLUMN_BYTES_DOWNLOADED_SO_FAR)); int totalBytes = c.getInt(c.getColumnIndexOrThrow(DownloadManager.COLUMN_TOTAL_SIZE_BYTES)); int state = c.getInt(c.getColumnIndex(DownloadManager.COLUMN_STATUS)); }} finally { if (c != null) { c.close(); }}
监听下载结束通知:
可以通过接收DownloadManager.ACTION_DOWNLOAD_COMPLETE广播来监听下载结束的通知
IntentFilter filter = new IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE); mReceiver = new BroadcastReceiver(){ public void onReceive(Context c,Intent i){ long downId = i.getLongExtra(DownloadManager.EXTRA_DOWNLOAD_ID,-1); } } context.registerReceiver(mReceiver,filter);
监听下载进度:
主要有三种方案:1.FileReceiver 2.ContentObserver 3.定时任务
class DownloadChangeObserver extends ContentObserver {public DownloadChangeObserver(){ super(handler);}@Overridepublic void onChange(boolean selfChange) { //查询进度}}//in activityprivate DownloadChangeObserver downloadObserver;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.download_manager_demo);……downloadObserver = new DownloadChangeObserver();}@Overrideprotected void onResume() { super.onResume(); /** observer download change **/ getContentResolver().registerContentObserver(DownloadManagerPro.CONTENT_URI, true, downloadObserver);}@Overrideprotected void onPause() { super.onPause(); getContentResolver().unregisterContentObserver(downloadObserver);}
上面这种做法可能对性能有些损耗,因为会不断触发onChange
推荐使用ScheduledExecutorService
public static ScheduledExecutorService scheduledExecutorService = Executors.newScheduledThreadPool(3);Runnable command = new Runnable() { @Override public void run() { updateView(); }};scheduledExecutorService.scheduleAtFixedRate(command, 0, 3, TimeUnit.SECONDS);
参考资料:
- http://www.trinea.cn/android/android-downloadmanager/
- http://www.trinea.cn/android/android-downloadmanager/
- https://github.com/Trinea/android-common/blob/master/src/cn/trinea/android/common/util/DownloadManagerPro.java
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