我正在尝试设置一个 Android 应用程序，该应用程序可以使用 Google Drive REST API Overview 中的指南操作存储在我的个人 Google Drive 帐户中的文件。 .

我已按照示例代码允许用户连接到帐户，但无论是选择帐户名还是按下取消按钮，“选择帐户”对话框都会不断出现。

我认为问题是 refreshResults() 方法在测试 mCredential.getSelectedAccountName() 时一直返回 null，即使已从帐户中选择了帐户名选择器对话框。但是不知道为什么会这样或如何解决它。如果更有经验的人能给我建议，我将不胜感激。谢谢。

我的代码如下:

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.");
            }
        }
    }


}

最佳答案

我遇到了完全相同的问题，在我的例子中，循环是由于我没有为我的应用创建凭据...

此处描述了详细信息:https://developers.google.com/drive/android/get-started

您必须为调试和生产环境检索 SHA-1 key ，并按照指南中的说明将它们添加到 Google Developers Console 的凭据中。

添加这些凭据后，循环立即停止。

关于android - 使用 Google Drive API 时出现无限 "Choose an account"循环，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/35503195/