android - 下载管理器有时显示不成功
问题描述
正如标题所说,我有一个下载管理器,它可以工作,但只是有时。这很奇怪,我找不到模式。我有一个按钮,单击该按钮时,会向服务器发送请求,该服务器返回要下载的文件,然后有时会下载,有时则不会。我看不到任何模式,也没有从电话或服务器收到任何错误。
这对我的应用程序不利,因为我需要知道它是否已成功下载,因此我要么需要找出它有时无法正常工作的原因,要么在下载失败时找到运行函数的方法。这是我用来下载文件的代码:
GlobalVariables globalVariables = new GlobalVariables();
String url = globalVariables.getIPAddress() + "downloadsong/" + Integer.toString(songId) + "/";
SharedPreferences sharedPreferences = getSharedPreferences("StoredValues", MODE_PRIVATE);
String token = sharedPreferences.getString("token", "null");
DownloadManager downloadManager = (DownloadManager)getSystemService(DOWNLOAD_SERVICE);
DownloadManager.Request request = new DownloadManager.Request(Uri.parse(url));
request.setTitle("Downloading");
request.setDescription("Downloading new titles");
request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
request.setDestinationInExternalPublicDir(Environment.DIRECTORY_MUSIC, "" + songId + ".mp3");
request.setAllowedNetworkTypes(DownloadManager.Request.NETWORK_WIFI);
request.addRequestHeader("Authorization", "Token " + token);
request.allowScanningByMediaScanner();
request.setAllowedOverMetered(true);
request.setAllowedOverRoaming(true);
long downloadReference = downloadManager.enqueue(request);
if (downloadReference != 0) {
Toast.makeText(getApplicationContext(), "download started", Toast.LENGTH_SHORT).show();
}else {
Toast.makeText(getApplicationContext(), "no download started", Toast.LENGTH_SHORT).show();
}
任何帮助或见解表示赞赏。谢谢!
解决方案
这是我的例子:
public class MainActivity extends AppCompatActivity {
private Button button;
private long downloadID;
private BroadcastReceiver onDownloadComplete = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
long id = intent.getLongExtra(DownloadManager.EXTRA_DOWNLOAD_ID, -1);
if (downloadID == id) {
validDownload(MainActivity.this, downloadID);
}
}
};
public void validDownload(Context context, long downloadId) {
DownloadManager dm = (DownloadManager) context.getSystemService(Context.DOWNLOAD_SERVICE);
if (dm != null) {
try (Cursor c = dm.query(new DownloadManager.Query().setFilterById(downloadId))) {
if (c.moveToFirst()) {
int status = c.getInt(c.getColumnIndex(DownloadManager.COLUMN_STATUS));
if (status == DownloadManager.STATUS_SUCCESSFUL) {
Toast.makeText(MainActivity.this, "Success", Toast.LENGTH_LONG).show();
} else if (status == DownloadManager.STATUS_FAILED) {
Toast.makeText(MainActivity.this, "Failed", Toast.LENGTH_LONG).show();
}
}
}
}
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
button = findViewById(R.id.download);
registerReceiver(onDownloadComplete, new IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE));
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
DownloadManager downloadManager = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);
if (downloadManager != null) {
downloadID = downloadManager.enqueue(prepareDownloadRequest());
}
}
});
}
private DownloadManager.Request prepareDownloadRequest() {
File file = new File(getExternalFilesDir(null), "Dummy");
DownloadManager.Request request = new DownloadManager.Request(Uri.parse("http://speedtest.ftp.otenet.gr/files/test10Mb.db"))
.setTitle("Dummy File")
.setDescription("Downloading")
.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE)
.setDestinationUri(Uri.fromFile(file))// Uri of the destination file
.setAllowedOverMetered(true)
.setAllowedOverRoaming(true);// Set if download is allowed on roaming networ
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
request.setRequiresCharging(false);
}
return request;
}
}
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