我正在使用暂停/恢复按钮构建一个简单的下载器应用程序。当我再次打开应用程序后，当我单击暂停按钮并终止应用程序时，下载进度不再显示。即使应用程序被杀，我也想保存下载进度状态。谁能帮我这个？我正在使用github上的download manager pro库构建应用程序。 这是代码： 活动类：
public class MainActivity extends AppCompatActivity {
String[] permissions = {
Manifest.permission.READ_EXTERNAL_STORAGE,
Manifest.permission.WRITE_EXTERNAL_STORAGE
};
public static final int REQUEST_ID_MULTIPLE_PERMISSIONS = 100;
EditText edt_url;
Button btn_download;
TextView fileNametv, ProgressbarTv;
private MyDownloadService mService;
ProgressBar progressBar;
String filename, url;
/* UrlFileNameListener listener;*/
Integer progress;
MyReceiver receiver;
public static MainActivity instance;
/* RecyclerView recyclerView;
List<Model> downloadList;
LinearLayoutManager manager;
DownloadAdapter adapter;
// ImageView pausebtn;
int position;*/
File myDirectory;
Boolean mBound = false;
Button pause_btn;
int tasktoken;
/* Model model;
Parcelable mListState;
private final String KEY_RECYCLER_STATE = "recycler_state";
private final String KEY_LIST_STATE = "list_state";*/
private ServiceConnection mServiceConnection = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
mBound = true;
MyDownloadService.LocalBinder localBinder = (MyDownloadService.LocalBinder) iBinder;
mService = localBinder.getService();
}
@Override
public void onServiceDisconnected(ComponentName componentName) {
mBound = false;
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
/* if(savedInstanceState!=null){
mListState = savedInstanceState.getParcelable(KEY_RECYCLER_STATE);
downloadList =savedInstanceState.getParcelableArrayList(KEY_LIST_STATE);
} */
setContentView(R.layout.activity_main);
edt_url = findViewById(R.id.edt_url);
btn_download = findViewById(R.id.btn_download);
pause_btn = findViewById(R.id.pause_resume);
/*recyclerView = findViewById(R.id.recycler_view);
downloadList = new ArrayList<>();
manager = new LinearLayoutManager(this);
adapter = new DownloadAdapter(downloadList, this);
recyclerView.setLayoutManager(manager);
DividerItemDecoration dividerItemDecoration = new DividerItemDecoration(recyclerView.getContext(),
manager.getOrientation());
recyclerView.addItemDecoration(dividerItemDecoration);
recyclerView.setAdapter(adapter);*/
fileNametv = findViewById(R.id.download_file_name);
ProgressbarTv = findViewById(R.id.progress_tv);
progressBar = findViewById(R.id.download_progress);
// pausebtn = findViewById(R.id.pause_resume);
instance = this;
/* if (progress!= null && filename != null) {
savedInstanceState.putInt("progress", progress);
savedInstanceState.putString("filename",filename);
// savedInstanceState.putString("filename", model.getFileName());
// savedInstanceState.putParcelable("list",mListState);
}*/
receiver = new MyReceiver();
btn_download.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
getDownloadProcess();
}
});
pause_btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
mService.pauseDownload(tasktoken);
}
});
LocalBroadcastManager.getInstance(this)
.registerReceiver(receiver,
new IntentFilter("download"));
if (checkAndRequestPermissions()) {
myDirectory = new File(Environment.getExternalStorageDirectory() + "/" + "RITSDownloads2");
if (!myDirectory.exists()) {
myDirectory.mkdir();
}
}
}
@Override
protected void onStart() {
super.onStart();
Intent intent = new Intent(this,MyDownloadService.class);
bindService(intent,mServiceConnection,Context.BIND_AUTO_CREATE);
}
@Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putInt("progress", progress);
outState.putString("filename",filename);
/* mListState = manager.onSaveInstanceState();
outState.putParcelable(KEY_RECYCLER_STATE,mListState);
outState.putParcelableArrayList(KEY_LIST_STATE, (ArrayList<? extends Parcelable>) adapter.getDownloadList());*/
}
@Override
protected void onPause() {
super.onPause();
//mListState = manager.onSaveInstanceState();
}
@Override
protected void onResume() {
super.onResume();
// manager.onRestoreInstanceState(mListState);
}
@Override
public void onBackPressed() {
progress = progressBar.getProgress();
super.onBackPressed();
}
/* @Override
public void onRestoreInstanceState(Bundle savedInstanceState, PersistableBundle persistentState) {
super.onRestoreInstanceState(savedInstanceState, persistentState);
manager.onRestoreInstanceState(mListState);
savedInstanceState.getParcelable(KEY_RECYCLER_STATE);
savedInstanceState.getParcelableArrayList(KEY_LIST_STATE);
}
*/
private void getDownloadProcess() {
url = edt_url.getText().toString();
filename = URLUtil.guessFileName(url, null, null);
//listener.setUrl(url,filename);
edt_url.setText("");
/* model = new Model();
model.setFileName(filename);
downloadList.add(model);
adapter.notifyDataSetChanged();*/
fileNametv.setText(filename);
Intent intent = new Intent(MainActivity.this, MyDownloadService.class);
intent.putExtra("filename", filename);
intent.putExtra("url", url);
intent.setAction(DownloadActions.ACTION.Download_ACTION);
startService(intent);
}
public class MyReceiver extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
progress = intent.getIntExtra("progress", 1);
ReportStructure reportStructure = MyDownloadService.downloadManagerPro.singleDownloadStatus(intent.getIntExtra("tasktoken",1));
tasktoken = intent.getIntExtra("tasktoken",1);
// model.setProgress(progress);
/*int position = downloadList.indexOf(model);
DownloadAdapter.DownloadHolder holder = getDownloadHolder(position);
holder.progressBar.setProgress(progress);*/
progressBar.setProgress(progress);
}
}
/* public DownloadAdapter.DownloadHolder getDownloadHolder(int position) {
return (DownloadAdapter.DownloadHolder) recyclerView.findViewHolderForLayoutPosition(position);
}
*/
@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
savedInstanceState.getInt("progress");
savedInstanceState.getString("filename");
/* Log.d("savedInstancestate",savedInstanceState.toString());
//savedInstanceState.getInt("position");
if(savedInstanceState!=null){
List<Model> downloadList = savedInstanceState.getParcelableArrayList(KEY_LIST_STATE);
adapter = new DownloadAdapter(downloadList,this);
}
*/
}
private boolean checkAndRequestPermissions() {
if (ContextCompat.checkSelfPermission(this, permissions[0]) != PackageManager.PERMISSION_GRANTED
&& ContextCompat.checkSelfPermission(this, permissions[1]) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(this, permissions, REQUEST_ID_MULTIPLE_PERMISSIONS);
return false;
} else {
return true;
}
}
@Override
public void onRequestPermissionsResult(int requestCode,
@NonNull String permissions[], @NonNull int[] grantResults) {
String TAG = "LOG_PERMISSION";
Log.d(TAG, "Permission callback called-------");
switch (requestCode) {
case REQUEST_ID_MULTIPLE_PERMISSIONS: {
Map<String, Integer> perms = new HashMap<>();
// Initialize the map with both permissions
perms.put(this.permissions[0], PackageManager.PERMISSION_GRANTED);
perms.put(this.permissions[1], PackageManager.PERMISSION_GRANTED);
// Fill with actual results from user
if (grantResults.length > 0) {
for (int i = 0; i < permissions.length; i++)
perms.put(permissions[i], grantResults[i]);
// Check for both permissions
if (perms.get(this.permissions[0]) == PackageManager.PERMISSION_GRANTED
&& perms.get(this.permissions[1]) == PackageManager.PERMISSION_GRANTED
) {
Log.d(TAG, "Phone state and storage permissions granted");
// process the normal flow
//else any one or both the permissions are not granted
//TODO Do your stuff here after permissions granted
} else {
Log.d(TAG, "Some permissions are not granted ask again ");
//permissions is denied (this is the first time, when "never ask again" is not checked) so ask again explaining the usage of permissions
// //shouldShowRequestPermissionRationale will return true
//show the dialog or snackbar saying its necessary and try again otherwise proceed with setup.
if (ActivityCompat.shouldShowRequestPermissionRationale(this, this.permissions[0]) ||
ActivityCompat.shouldShowRequestPermissionRationale(this, this.permissions[1])) {
showDialogOK("Phone state and storage permissions required for this app",
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
switch (which) {
case DialogInterface.BUTTON_POSITIVE:
checkAndRequestPermissions();
break;
case DialogInterface.BUTTON_NEGATIVE:
// proceed with logic by disabling the related features or quit the app.
break;
}
}
});
}
//permissions is denied (and never ask again is checked)
//shouldShowRequestPermissionRationale will return false
else {
Toast.makeText(this, "Go to settings and enable permissions", Toast.LENGTH_LONG)
.show();
//proceed with logic by disabling the related features or quit the app.
}
}
}
}
}
}
private void showDialogOK(String message, DialogInterface.OnClickListener okListener) {
new AlertDialog.Builder(this)
.setMessage(message)
.setPositiveButton("OK", okListener)
.setNegativeButton("Cancel", okListener)
.create()
.show();
}
}
Service Class:
public class MyDownloadService extends Service implements DownloadManagerListener {
private static final String LOG_TAG = "tag";
public static DownloadManagerPro downloadManagerPro;
File myDirectory;
int taskToken;
String name;
Intent notificationIntent;
Notification notification;
PendingIntent pendingIntent;
private IBinder binder = new LocalBinder();
@Nullable
@Override
public IBinder onBind(Intent intent) {
return binder;
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
if (intent.getAction().equals(DownloadActions.ACTION.Download_ACTION)) {
Log.d(LOG_TAG, "Received Start Foreground Intent");
}
name = intent.getStringExtra("filename");
final String url = intent.getStringExtra("url");
Log.d(LOG_TAG, name);
Log.d(LOG_TAG, url);
downloadManagerPro = new DownloadManagerPro(this.getApplicationContext());
downloadManagerPro.init("RITSDownloads2/", 16, this);
myDirectory = new File(Environment.getExternalStorageDirectory() + "/" + "RITSDownloads2");
if (!myDirectory.exists()) {
myDirectory.mkdir();
}
taskToken = downloadManagerPro.addTask(name, url, 16, true, true);
Log.d(LOG_TAG, String.valueOf(taskToken));
try {
downloadManagerPro.startDownload(taskToken);
notificationIntent = new Intent(this, MainActivity.class);
notificationIntent.setAction(DownloadActions.ACTION.Download_ACTION);
pendingIntent = PendingIntent.getActivity(this, 0,
notificationIntent, 0);
notification = new NotificationCompat.Builder(this)
.setContentTitle("Downloading")
.setTicker("Rits Download")
.setContentText(name)
.setSmallIcon(android.R.drawable.stat_sys_download)
.setContentIntent(pendingIntent)
.setOngoing(true)
.build();
startForeground(DownloadActions.NOTIFICATION_ID.FOREGROUND_SERVICE,
notification);
// stopForeground(true);
// stopSelf();
} catch (IOException e) {
e.printStackTrace();
}
return START_STICKY;
}
@Override
public void OnDownloadStarted(long taskId) {
Log.d(LOG_TAG, "DownloadStarted");
}
@Override
public void OnDownloadPaused(long taskId) {
}
@Override
public void onDownloadProcess(long taskId, double percent, long downloadedLength) {
final int progress = (int) percent;
final int taskToken = (int) taskId;
// int position = positions.get(taskToken);
notification = new NotificationCompat.Builder(this)
.setContentTitle("Downloading")
.setTicker("Rits Download")
.setContentText(name)
.setSmallIcon(android.R.drawable.stat_sys_download)
.setContentIntent(pendingIntent)
.setOngoing(true)
.setColor(ContextCompat.getColor(this, R.color.colorPrimary))
.setProgress(100, progress, false)
.build();
startForeground(DownloadActions.NOTIFICATION_ID.FOREGROUND_SERVICE,
notification);
Intent intent = new Intent(this, MainActivity.class);
intent.putExtra("progress", progress);
intent.setAction("download");
intent.putExtra("tasktoken",taskToken);
ReportStructure structure = downloadManagerPro.singleDownloadStatus(taskToken);
String name =structure.name;
intent.putExtra("name",name);
LocalBroadcastManager.getInstance(getApplicationContext()).sendBroadcast(intent);
}
@Override
public void OnDownloadFinished(long taskId) {
}
@Override
public void OnDownloadRebuildStart(long taskId) {
}
@Override
public void OnDownloadRebuildFinished(long taskId) {
}
public void pauseDownload(int taskToken){
ReportStructure reportStructure = downloadManagerPro.singleDownloadStatus(taskToken);
if(reportStructure.state == TaskStates.DOWNLOADING){
downloadManagerPro.pauseDownload(taskToken);
} else if(reportStructure.state == TaskStates.PAUSED){
try {
downloadManagerPro.startDownload(taskToken);
} catch (IOException e) {
e.printStackTrace();
}
}
}
@Override
public void OnDownloadCompleted(long taskId) {
Log.d(LOG_TAG, "Download Complete");
/* MainActivity.instance.pausebtn.post(new Runnable() {
@Override
public void run() {
MainActivity.instance.pausebtn.setImageDrawable(getResources().getDrawable(R.drawable.ic_action_done));
}
});*/
notification = new NotificationCompat.Builder(this)
.setContentTitle("Download Complete")
.setTicker("Rits Download")
.setContentText(name)
.setSmallIcon(R.drawable.ic_action_done)
.setContentIntent(pendingIntent)
.setOngoing(true)
.setColor(ContextCompat.getColor(this, R.color.colorPrimary))
.build();
startForeground(DownloadActions.NOTIFICATION_ID.FOREGROUND_SERVICE,
notification);
}
@Override
public void connectionLost(long taskId) {
}
@Override
public void onTaskRemoved(Intent rootIntent) {
/* Intent restartService = new Intent(getApplicationContext(),this.getClass());
restartService.setPackage(getPackageName());
PendingIntent restartPendingIntent =PendingIntent.getService(getApplicationContext(), 1,restartService, PendingIntent.FLAG_ONE_SHOT);
AlarmManager myAlarmService = (AlarmManager) getApplicationContext().getSystemService(Context.ALARM_SERVICE);
myAlarmService.set(
AlarmManager.ELAPSED_REALTIME,
SystemClock.elapsedRealtime() + 1000,
restartPendingIntent);*/
}
public class LocalBinder extends Binder{
public MyDownloadService getService(){
return MyDownloadService.this;
}
}
}
答案 0 :(得分：0)
我不知道你想如何保存状态，但我知道一个活动有一个onStop()方法可以覆盖。
当应用程序被杀死时onStop()方法运行，所以我想你会想要在这种方法中“保存”。
至于保存的东西，我相信你会想要使用SharedPreferences类。您可以找到有关here的更多信息。
您可以找到活动的生命周期here
希望这会有所帮助
答案 1 :(得分：0)
在SharedPreferences onDestroy（）上保存进度，并在创建活动时从那里检索它。
高速缓存：
@Override
protected void onDestroy() {
super.onDestroy();
SharedPreferences sharedPreferences = getSharedPreferences("space_name", MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.putInt("progress", progress).apply();
}
并检索：
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
SharedPreferences sharedPreferences = getSharedPreferences("space_name", MODE_PRIVATE);
progress = sharedPreferences.getInt("progress", 0); // 0 default value in case is empty
}