我想从一个URL下载一个二进制文件。我是否可以使用我在这里找到的Android DownloadManager类(DownloadManager类)?
我想从一个URL下载一个二进制文件。我是否可以使用我在这里找到的Android DownloadManager类(DownloadManager类)?
我在这里找到了Android下载管理器类,是否可以使用?
是的,但只能在Android API Level 9(2.3版本)及以上版本中使用。这里有一个示例项目,演示了如何使用DownloadManager
。
DownloadManager
不支持 SFTP。据我所知,Android 中没有任何支持 SFTP 的东西。你需要找一个第三方的 JAR 包来实现。 - CommonsWare使用DownloadManager类(仅适用于GingerBread及更高版本)
GingerBread引入了一个新功能——DownloadManager,它允许您轻松下载文件并将处理线程、流等繁重工作委托给系统。
首先,让我们看一个实用方法:
/**
* @param context used to check the device version and DownloadManager information
* @return true if the download manager is available
*/
public static boolean isDownloadManagerAvailable(Context context) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.GINGERBREAD) {
return true;
}
return false;
}
方法的名称已经解释了一切。一旦确定DownloadManager可用,您可以执行以下操作:
String url = "url you want to download";
DownloadManager.Request request = new DownloadManager.Request(Uri.parse(url));
request.setDescription("Some descrition");
request.setTitle("Some title");
// in order for this if to run, you must use the android 3.2 to compile your app
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
request.allowScanningByMediaScanner();
request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
}
request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, "name-of-the-file.ext");
// get download service and enqueue file
DownloadManager manager = (DownloadManager) getSystemService(Context.DOWNLOAD_SERVICE);
manager.enqueue(request);
下载进度将会显示在通知栏中。
DownloadManager downloadmanager = (DownloadManager) getSystemService(Context.DOWNLOAD_SERVICE);
Uri uri = Uri.parse("http://www.example.com/myfile.mp3");
DownloadManager.Request request = new DownloadManager.Request(uri);
request.setTitle("My File");
request.setDescription("Downloading");
request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
request.setDestinationUri(Uri.parse("file://" + folderName + "/myfile.mp3"));
downloadmanager.enqueue(request);
确保在你的 Manifest.xml 文件中包含 READ_EXTERNAL_STORAGE 和 WRITE_EXTERNAL_STORAGE 权限:
接着在你的下载函数中加入以下代码:
if(ActivityCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED
|| ActivityCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED){
// this will request for permission when user has not granted permission for the app
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE, Manifest.permission.WRITE_EXTERNAL_STORAGE}, 1);
}
else{
//Download Script
DownloadManager downloadManager = (DownloadManager) getSystemService(Context.DOWNLOAD_SERVICE);
Uri uri = Uri.parse("URL of file to download");
DownloadManager.Request request = new DownloadManager.Request(uri);
request.setVisibleInDownloadsUi(true);
request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, uri.getLastPathSegment());
downloadManager.enqueue(request);
}