Question

我想从网址下载二进制文件。是否可以使用我在此处DownloadManager class找到的Android下载管理器课程？

Answer 1

是否可以使用我在这里找到的android下载管理器类

是的，尽管只有Android API Level 9（版本2.3）才可用。 Here is a sample project演示了DownloadManager的使用情况。

Answer 2

使用DownloadManager类（仅限GingerBread和更新版本）

GingerBread带来了一个新功能DownloadManager，它允许您轻松下载文件并将处理线程，流等的艰苦工作委派给系统。

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;
}

方法的名称解释了这一切。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);

下载进度将显示在通知栏中。

Answer 3

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);

Answer 4

确保READ_EXTERNAL_STORAGE和WRITE_EXTERNAL_STORAGE权限在您的Manifest.xml文件中：

然后将此代码包含在您的下载功能中

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);
 }

Android：如何使用下载管理器类？

4 个答案: