问题
I'm trying to set up an Android app that can manipulate files stored on my personal Google Drive account using the guidelines at Google Drive REST API Overview.
I've followed the sample code to allow a user to connect to the account, but the "Choose an account" dialog reappears continually regardless of whether an account name is chosen or the cancel button is pressed.
I believe the problem is that the refreshResults() method keeps returning null when testing for mCredential.getSelectedAccountName() even after an account name has been selected from the account chooser dialog. However don't know why this is happening or how to fix it. I'd greatly appreciate it if someone more experienced could advise me. Thanks.
My code is as follows:
import android.accounts.AccountManager;
import android.app.Dialog;
import android.app.ProgressDialog;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.AsyncTask;
import android.preference.PreferenceManager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.GoogleApiAvailability;
import com.google.api.client.extensions.android.http.AndroidHttp;
import com.google.api.client.googleapis.extensions.android.gms.auth.GoogleAccountCredential;
import com.google.api.client.googleapis.extensions.android.gms.auth.GooglePlayServicesAvailabilityIOException;
import com.google.api.client.googleapis.extensions.android.gms.auth.UserRecoverableAuthIOException;
import com.google.api.client.http.HttpTransport;
import com.google.api.client.json.JsonFactory;
import com.google.api.client.json.jackson2.JacksonFactory;
import com.google.api.client.util.ExponentialBackOff;
import com.google.api.services.drive.DriveScopes;
import com.google.api.services.drive.model.File;
import com.google.api.services.drive.model.FileList;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class HomeActivity extends AppCompatActivity{
GoogleAccountCredential mCredential;
ProgressDialog mProgress;
static final int REQUEST_ACCOUNT_PICKER = 1000;
static final int REQUEST_AUTHORIZATION = 1001;
static final int REQUEST_GOOGLE_PLAY_SERVICES = 1002;
private static final String PREF_ACCOUNT_NAME = "accountName";
private static final String[] SCOPES = { DriveScopes.DRIVE_METADATA_READONLY };
public TextView mOutputText;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Initialize credentials and service object.
SharedPreferences settings = getPreferences(Context.MODE_PRIVATE);
mCredential = GoogleAccountCredential.usingOAuth2(
getApplicationContext(), Arrays.asList(SCOPES))
.setBackOff(new ExponentialBackOff())
.setSelectedAccountName(settings.getString(PREF_ACCOUNT_NAME, null));
mProgress = new ProgressDialog(this);
mProgress.setMessage("Calling Drive API ...");
setContentView(R.layout.activity_home);
mOutputText = (TextView) findViewById(R.id.textStatus);
@Override
protected void onResume() {
super.onResume();
if (isGooglePlayServicesAvailable()) {
refreshResults();
} else {
mOutputText.setText("Google Play Services required: " +
"after installing, close and relaunch this app.");
}
}
/**
* Called when an activity launched here (specifically, AccountPicker
* and authorization) exits, giving you the requestCode you started it with,
* the resultCode it returned, and any additional data from it.
* @param requestCode code indicating which activity result is incoming.
* @param resultCode code indicating the result of the incoming
* activity result.
* @param data Intent (containing result data) returned by incoming
* activity result.
*/
@Override
protected void onActivityResult(
int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
switch(requestCode) {
case REQUEST_GOOGLE_PLAY_SERVICES:
if (resultCode != RESULT_OK) {
isGooglePlayServicesAvailable();
}
break;
case REQUEST_ACCOUNT_PICKER:
if (resultCode == RESULT_OK && data != null &&
data.getExtras() != null) {
String accountName =
data.getStringExtra(AccountManager.KEY_ACCOUNT_NAME);
if (accountName != null) {
mCredential.setSelectedAccountName(accountName);
SharedPreferences settings =
getPreferences(Context.MODE_PRIVATE);
SharedPreferences.Editor editor = settings.edit();
editor.putString(PREF_ACCOUNT_NAME, accountName);
editor.apply();
}
} else if (resultCode == RESULT_CANCELED) {
mOutputText.setText("Account unspecified.");
}
break;
case REQUEST_AUTHORIZATION:
if (resultCode != RESULT_OK) {
chooseAccount();
}
break;
}
super.onActivityResult(requestCode, resultCode, data);
}
/**
* Attempt to get a set of data from the Drive API to display. If the
* email address isn't known yet, then call chooseAccount() method so the
* user can pick an account.
*/
private void refreshResults() {
if (mCredential.getSelectedAccountName() == null) {
chooseAccount();
} else {
if (isDeviceOnline()) {
new MakeRequestTask(mCredential).execute();
} else {
mOutputText.setText("No network connection available.");
}
}
}
/**
* Starts an activity in Google Play Services so the user can pick an
* account.
*/
private void chooseAccount() {
startActivityForResult(
mCredential.newChooseAccountIntent(), REQUEST_ACCOUNT_PICKER);
}
/**
* Checks whether the device currently has a network connection.
* @return true if the device has a network connection, false otherwise.
*/
private boolean isDeviceOnline() {
ConnectivityManager connMgr =
(ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();
return (networkInfo != null && networkInfo.isConnected());
}
/**
* Check that Google Play services APK is installed and up to date. Will
* launch an error dialog for the user to update Google Play Services if
* possible.
* @return true if Google Play Services is available and up to
* date on this device; false otherwise.
*/
private boolean isGooglePlayServicesAvailable() {
final int connectionStatusCode =
//GooglePlayServicesUtil.isGooglePlayServicesAvailable(this);
GoogleApiAvailability.getInstance().isGooglePlayServicesAvailable(this);
if (GoogleApiAvailability.getInstance().isUserResolvableError(connectionStatusCode)) {
showGooglePlayServicesAvailabilityErrorDialog(connectionStatusCode);
return false;
} else if (connectionStatusCode != ConnectionResult.SUCCESS ) {
return false;
}
return true;
}
/**
* Display an error dialog showing that Google Play Services is missing
* or out of date.
* @param connectionStatusCode code describing the presence (or lack of)
* Google Play Services on this device.
*/
void showGooglePlayServicesAvailabilityErrorDialog(
final int connectionStatusCode) {
//Dialog dialog = GooglePlayServicesUtil.getErrorDialog(
Dialog dialog = GoogleApiAvailability.getInstance().getErrorDialog(
HomeActivity.this,
connectionStatusCode,
REQUEST_GOOGLE_PLAY_SERVICES);
dialog.show();
}
/**
* An asynchronous task that handles the Drive API call.
* Placing the API calls in their own task ensures the UI stays responsive.
*/
private class MakeRequestTask extends AsyncTask<Void, Void, List<String>> {
private com.google.api.services.drive.Drive mService = null;
private Exception mLastError = null;
public MakeRequestTask(GoogleAccountCredential credential) {
HttpTransport transport = AndroidHttp.newCompatibleTransport();
JsonFactory jsonFactory = JacksonFactory.getDefaultInstance();
mService = new com.google.api.services.drive.Drive.Builder(
transport, jsonFactory, credential)
.setApplicationName("Media Vault")
.build();
}
/**
* Background task to call Drive API.
* @param params no parameters needed for this task.
*/
@Override
protected List<String> doInBackground(Void... params) {
try {
return getDataFromApi();
} catch (Exception e) {
mLastError = e;
cancel(true);
return null;
}
}
/**
* Fetch a list of up to 10 file names and IDs.
* @return List of Strings describing files, or an empty list if no files
* found.
* @throws IOException
*/
private List<String> getDataFromApi() throws IOException {
// Get a list of up to 10 files.
List<String> fileInfo = new ArrayList<String>();
FileList result = mService.files().list()
.setPageSize(10)
.setFields("nextPageToken, items(id, name)")
.execute();
List<File> files = result.getFiles();
if (files != null) {
for (File file : files) {
fileInfo.add(String.format("%s (%s)\n",
file.getName(), file.getId()));
}
}
return fileInfo;
}
@Override
protected void onPreExecute() {
mOutputText.setText("");
mProgress.show();
}
@Override
protected void onPostExecute(List<String> output) {
mProgress.hide();
if (output == null || output.size() == 0) {
mOutputText.setText("No results returned.");
} else {
output.add(0, "Data retrieved using the Drive API:");
mOutputText.setText(TextUtils.join("\n", output));
}
}
@Override
protected void onCancelled() {
mProgress.hide();
if (mLastError != null) {
if (mLastError instanceof GooglePlayServicesAvailabilityIOException) {
showGooglePlayServicesAvailabilityErrorDialog(
((GooglePlayServicesAvailabilityIOException) mLastError)
.getConnectionStatusCode());
} else if (mLastError instanceof UserRecoverableAuthIOException) {
startActivityForResult(
((UserRecoverableAuthIOException) mLastError).getIntent(),
HomeActivity.REQUEST_AUTHORIZATION);
} else {
mOutputText.setText("The following error occurred:\n"
+ mLastError.getMessage());
}
} else {
mOutputText.setText("Request cancelled.");
}
}
}
}
回答1:
I got the exact same problem, in my case the loop was due to the fact that I did not create my credentials for my app...
The details are described here: https://developers.google.com/drive/android/get-started
You must retrieve your SHA-1 keys for both the debug and production environments and add them in your credentials in the Google Developers Console as described in the guide.
Once I added these credentials, the loop stopped right away.
回答2:
One thing I can think of is that the value of setSelectedAccountName will default in to null if no PREF_ACCOUNT_NAME was retrieved, so this may contribute to the issue.
The only difference I can see that you did was how you instantiated the mCredential. Try to check out the Authorizing requests for Android (using GoogleApiClient instead of GoogleAccountCredential.
回答3:
You must be using the official Google Drive Api Quickstart by Google. Link. I can confirm that it doesn't work unfortunately as of now. It leads to an infinite login loop even if I have only one gmail account on my device. Maybe consider using the code at their Drive Api page as a starting point. That should work
来源：https://stackoverflow.com/questions/35503195/infinite-choose-an-account-loop-when-using-google-drive-api