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我有一個應用程序，需要先詢問兩個權限，才能讀取聯繫人並在extrernal存儲中寫入文件。問題是，當應用程序在第一次崩潰時打開並請求權限，當我重新打開它時，一切都很好，應用程序運行順利。 MainActivity.javaAndroid請求多權限
public class MainActivity extends AppCompatActivity implements
LoaderManager.LoaderCallbacks<Cursor>,
AdapterView.OnItemClickListener,
GoogleApiClient.ConnectionCallbacks,
GoogleApiClient.OnConnectionFailedListener
{
/**
* Global variables
*/
private static final int PERMISSIONS_REQUEST_READ_CONTACTS = 100;
private ListView mContactsList; //the listview to display contacts
private LinearLayout contactLayout; //the listview item layout for each contact
private SimpleCursorAdapter mCursorAdapter; // An adapter that binds the result Cursor to the ListView
private boolean bigmode = false; //flag indicating whether we are currently using the normal or big contact layout
public GoogleApiClient mApiClient; //client to the google play services activity detection
private int activityDetectionInterval = 3000; //how often to request an activity detection in milliseconds
/*
* Defines an array that contains column names to move from
* the Cursor to the ListView (we really just want the name).
*/
private final static String[] FROM_COLUMNS = {
ContactsContract.Contacts.DISPLAY_NAME
};
/*
* Defines an array that contains column names to retrieve from the
* contacts DB when we query it (we really just want the name).
*/
private static final String[] PROJECTION =
{
ContactsContract.Contacts._ID,
ContactsContract.Contacts.DISPLAY_NAME
};
/*
* Defines an array that contains resource ids for the listview item layout views
* that get the Cursor column contents.
*/
private final static int[] TO_IDS = {
R.id.label
};
/**
* Methods
*/
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
askpermissions();
/* showContacts(); // Ask permission to read contacts
showlogs(); // Ask permission to create file where we write the logs*/
setContentView(R.layout.activity_main);
// set up the action toolbar
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
// set up the listview by retrieving contacts
mContactsList = (ListView) findViewById(R.id.listView);
//setup an adapter to populate the listview
mCursorAdapter = new SimpleCursorAdapter(
this,
R.layout.contacts_list_item,
null,
FROM_COLUMNS, TO_IDS,
0);
// Sets the adapter for the ListView
mContactsList.setAdapter(mCursorAdapter);
// set up the listener for the listview - it will be handled by code in this activity
mContactsList.setOnItemClickListener(this);
//call the cursor loader
getLoaderManager().initLoader(0, null, this);
// set up the "zoom" button
final FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
// set up the click action - toggle between big and normal layouts
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
toggleDisplaySize();
}
});
// set up the client for google play services so we can request activity detection later
Log.i("START", "Start");
writefile("START");
mApiClient = new GoogleApiClient.Builder(this)
.addApi(ActivityRecognition.API)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.build();
mApiClient.connect();
mContactsList.setOnScrollListener(new AbsListView.OnScrollListener() {
@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
Log.i("Scroll", "Scroll list"); // When user scrolled the list
writefile("SCROLL");
}
@Override
public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
}
});}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* when the application is ready to be brought to the front, we must assess whether to use
* the big or normal layouts
*/
@Override
public void onResume() {
super.onResume();
//check the shared preference value set by the activity detection service
SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(this);
if (sp.getBoolean("isWalking", false)) {
bigmode = false;
} else {
bigmode = true;
}
//set the appropriate layout for the listview
toggleDisplaySize();
}
@Override
public Loader<Cursor> onCreateLoader(int i, Bundle bundle) {
// Starts the query and returns the result cursor
// we only want the "name" column and also we want it sorted alphabetically
return new CursorLoader(
this,
ContactsContract.Contacts.CONTENT_URI,
PROJECTION,
null,
null,
"DISPLAY_NAME ASC"
);
}
@Override
public void onLoadFinished(Loader<Cursor> loader, Cursor cursor) {
// Put the result Cursor in the adapter for the ListView
//Log.i("CursorLoaderFinished", "retrieved "+ cursor.getCount()+" contacts");
mCursorAdapter.swapCursor(cursor);
}
@Override
public void onLoaderReset(Loader<Cursor> loader) {
// Delete the reference to the existing Cursor
mCursorAdapter.swapCursor(null);
}
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
// show a toast with the contact name
Log.i("onItemClick", "Click");
writefile("CLICK "+String.valueOf(((TextView) view.findViewById(R.id.label)).getText()));
Log.i("Name", String.valueOf(((TextView) view.findViewById(R.id.label)).getText()));
//writefile(String.valueOf(((TextView) view.findViewById(R.id.label)).getText()));
Toast.makeText(this, ((TextView) view.findViewById(R.id.label)).getText(), Toast.LENGTH_SHORT).show();
}
/**
* the google play services client is ready, now we can start requesting activity
* detection updates from it
*/
@Override
public void onConnected(@Nullable Bundle bundle) {
//create an intent pointing to the background service which will update our current activity
Intent intent = new Intent(this, ActivityRecognizedService.class);
PendingIntent pendingIntent = PendingIntent.getService(this, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);
//request updates
ActivityRecognition.ActivityRecognitionApi.requestActivityUpdates(mApiClient, activityDetectionInterval, pendingIntent);
}
@Override
public void onConnectionSuspended(int i) {
}
@Override
public void onConnectionFailed(@NonNull ConnectionResult connectionResult) {
}
/**
* this method selects and sets the appropriate listview layout according to whether we should
* be in big or normal mode (either from a zoom button click, or because the service has detected
* that we are currently walking
*/
public void toggleDisplaySize() {
int layoutid;
if (!bigmode) {
Log.i("ZOOM", "1");//ZOOM IN
writefile("ZOOM_1");
layoutid = R.layout.contacts_list_item_big;
bigmode = true;
} else {
Log.i("ZOOM", "0");//ZOOM OUT
writefile("ZOOM_0");
layoutid = R.layout.contacts_list_item;
bigmode = false;
}
mCursorAdapter = new SimpleCursorAdapter(
getApplicationContext(),
layoutid,
null,
FROM_COLUMNS, TO_IDS,
0);
mContactsList.setAdapter(mCursorAdapter);
getLoaderManager().initLoader(0, null, MainActivity.this);
}
/*
private void showContacts() {
// Check the SDK version and whether the permission is already granted or not. To get te contacts
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M && checkSelfPermission(Manifest.permission.READ_CONTACTS) != PackageManager.PERMISSION_GRANTED) {
requestPermissions(new String[]{Manifest.permission.READ_CONTACTS}, PERMISSIONS_REQUEST_READ_CONTACTS);
ActivityCompat.requestPermissions(this, new String[]{android.Manifest.permission.WRITE_EXTERNAL_STORAGE}, 1);
}
}
private void showlogs() {
//Check the SDK version and whether the permission is already granted or not. To be able to create and write in file
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if (checkSelfPermission(android.Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(this, new String[]{android.Manifest.permission.WRITE_EXTERNAL_STORAGE}, 1);
}
}
}*/
public void askpermissions(){
int PERMISSION_ALL = 1;
String[] PERMISSIONS = {Manifest.permission.READ_CONTACTS, Manifest.permission.WRITE_EXTERNAL_STORAGE};
if(!hasPermissions(this, PERMISSIONS)){
ActivityCompat.requestPermissions(this, PERMISSIONS, PERMISSION_ALL);
}
}
public static boolean hasPermissions(Context context, String... permissions) {
if (android.os.Build.VERSION.SDK_INT >= Build.VERSION_CODES.M && context != null && permissions != null) {
for (String permission : permissions) {
if (ActivityCompat.checkSelfPermission(context, permission) != PackageManager.PERMISSION_GRANTED) {
return false;
}
}
}
return true;
}
public void writefile(String te){
//Write in file the logs
te =gettime()+' '+te+'\n';
File file = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS), "Logs");
if (! file.exists()){
try {
file.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
}
FileWriter fileWriter = null;
try {
fileWriter = new FileWriter(file,true);
} catch (IOException e) {
e.printStackTrace();
}
try {
fileWriter.write(te);
} catch (IOException e) {
e.printStackTrace();
}
try {
fileWriter.flush();
} catch (IOException e) {
e.printStackTrace();
}
try {
fileWriter.close();
} catch (IOException e) {
e.printStackTrace();
}
}
public String gettime(){
String timeStamp = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new java.util.Date());
return timeStamp;
}
}
我請求許可與askpermissions（）;函數...有什麼想法可以是我的代碼錯誤？
因爲askpermissions不堵......所以很明顯，即使你沒有權限整個的onCreate代碼被稱爲......包括initLoader – Selvin
因爲我只是一個初學者機器人，你能告訴我如何做到這一點？ thx –
是的當然...在官方Android開發者網站上找到指南，並按照它... – Selvin