我正在编写一个需要用户登录的应用程序。
我想通过Google+实施，并按照以下文章设置我的登录活动LoginActivity：
流程：
MainActivity LoginActivity。否则，它仍保留在MainActivity。如何在MainActivity中检查用户是否已登录？
以下是LoginActivity.java的代码：
包com.noideabox.googlelogin;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.SignInButton;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.common.api.GoogleApiClient.ConnectionCallbacks;
import com.google.android.gms.common.api.GoogleApiClient.OnConnectionFailedListener;
import com.google.android.gms.plus.Plus;
import com.google.android.gms.plus.model.people.Person;
import android.app.PendingIntent;
import android.content.Intent;
import android.content.IntentSender.SendIntentException;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
public class LoginActivity extends FragmentActivity implements
ConnectionCallbacks, OnConnectionFailedListener, View.OnClickListener {
private static final String TAG = "android-plus-quickstart";
private static final int STATE_DEFAULT = 0;
private static final int STATE_SIGN_IN = 1;
private static final int STATE_IN_PROGRESS = 2;
private static final int RC_SIGN_IN = 0;
private static final String SAVED_PROGRESS = "sign_in_progress";
private GoogleApiClient mGoogleApiClient;
// We use mSignInProgress to track whether user has clicked sign in.
// mSignInProgress can be one of three values:
//
// STATE_DEFAULT: The default state of the application before the user
// has clicked 'sign in', or after they have clicked
// 'sign out'. In this state we will not attempt to
// resolve sign in errors and so will display our
// Activity in a signed out state.
// STATE_SIGN_IN: This state indicates that the user has clicked 'sign
// in', so resolve successive errors preventing sign in
// until the user has successfully authorized an account
// for our app.
// STATE_IN_PROGRESS: This state indicates that we have started an intent to
// resolve an error, and so we should not start further
// intents until the current intent completes.
private int mSignInProgress;
// Used to store the PendingIntent most recently returned by Google Play
// services until the user clicks 'sign in'.
private PendingIntent mSignInIntent;
private SignInButton mSignInButton;
private Button mSignOutButton;
private Button mRevokeButton;
private TextView mStatus;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
mSignInButton = (SignInButton) findViewById(R.id.sign_in_button);
mSignOutButton = (Button) findViewById(R.id.sign_out_button);
mRevokeButton = (Button) findViewById(R.id.revoke_access_button);
mStatus = (TextView) findViewById(R.id.sign_in_status);
mSignInButton.setOnClickListener(this);
mSignOutButton.setOnClickListener(this);
mRevokeButton.setOnClickListener(this);
if (savedInstanceState != null) {
mSignInProgress = savedInstanceState.getInt(SAVED_PROGRESS, STATE_DEFAULT);
}
mGoogleApiClient = build_GoogleApiClient();
}
@Override
protected void onStart() {
super.onStart();
mGoogleApiClient.connect();
}
@Override
protected void onStop() {
super.onStop();
if (mGoogleApiClient.isConnected()) {
mGoogleApiClient.disconnect();
}
}
@Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putInt(SAVED_PROGRESS, mSignInProgress);
}
@Override
public void onClick(View v) {
if (!mGoogleApiClient.isConnecting()) {
// We only process button clicks when GoogleApiClient is not
// transitioning
// between connected and not connected.
switch (v.getId()) {
case R.id.sign_in_button:
mStatus.setText(R.string.status_signing_in);
resolveSignInError();
break;
case R.id.sign_out_button:
// We clear the default account on sign out so that Google Play
// services will not return an onConnected callback without user
// interaction.
Plus.AccountApi.clearDefaultAccount(mGoogleApiClient);
mGoogleApiClient.disconnect();
mGoogleApiClient.connect();
break;
case R.id.revoke_access_button:
// After we revoke permissions for the user with a
// GoogleApiClient
// instance, we must discard it and create a new one.
Plus.AccountApi.clearDefaultAccount(mGoogleApiClient);
// Our sample has caches no user data from Google+, however we
// would normally register a callback on
// revokeAccessAndDisconnect
// to delete user data so that we comply with Google developer
// policies.
Plus.AccountApi.revokeAccessAndDisconnect(mGoogleApiClient);
mGoogleApiClient = build_GoogleApiClient();
mGoogleApiClient.connect();
break;
}
}
}
/*
* onConnected is called when our Activity successfully connects to Google
* Play services. onConnected indicates that an account was selected on the
* device, that the selected account has granted any requested permissions
* to our app and that we were able to establish a service connection to
* Google Play services.
*/
@Override
public void onConnected(Bundle connectionHint) {
// Reaching onConnected means we consider the user signed in.
Log.i(TAG, "onConnected");
// Update the user interface to reflect that the user is signed in.
mSignInButton.setEnabled(false);
mSignOutButton.setEnabled(true);
mRevokeButton.setEnabled(true);
// Retrieve some profile information to personalize our app for the
// user.
Person currentUser = Plus.PeopleApi.getCurrentPerson(mGoogleApiClient);
mStatus.setText(String.format(
getResources().getString(R.string.signed_in_as),
currentUser.getDisplayName()
));
// Indicate that the sign in process is complete.
mSignInProgress = STATE_DEFAULT;
Toast.makeText(this, mStatus.getText(), Toast.LENGTH_LONG).show();
}
/*
* onConnectionFailed is called when our Activity could not connect to
* Google Play services. onConnectionFailed indicates that the user needs to
* select an account, grant permissions or resolve an error in order to sign
* in.
*/
@Override
public void onConnectionFailed(ConnectionResult result) {
// Refer to the javadoc for ConnectionResult to see what error codes
// might
// be returned in onConnectionFailed.
Log.i(TAG, "onConnectionFailed: ConnectionResult.getErrorCode() = " + result.getErrorCode());
if (mSignInProgress != STATE_IN_PROGRESS) {
// We do not have an intent in progress so we should store the
// latest
// error resolution intent for use when the sign in button is
// clicked.
mSignInIntent = result.getResolution();
if (mSignInProgress == STATE_SIGN_IN) {
// STATE_SIGN_IN indicates the user already clicked the sign in
// button
// so we should continue processing errors until the user is
// signed in
// or they click cancel.
resolveSignInError();
}
}
// In this sample we consider the user signed out whenever they do not
// have
// a connection to Google Play services.
onSignedOut();
}
/*
* Starts an appropriate intent or dialog for user interaction to resolve
* the current error preventing the user from being signed in. This could be
* a dialog allowing the user to select an account, an activity allowing the
* user to consent to the permissions being requested by your app, a setting
* to enable device networking, etc.
*/
private void resolveSignInError() {
if (mSignInIntent != null) {
// We have an intent which will allow our user to sign in or
// resolve an error. For example if the user needs to
// select an account to sign in with, or if they need to consent
// to the permissions your app is requesting.
try {
// Send the pending intent that we stored on the most recent
// OnConnectionFailed callback. This will allow the user to
// resolve the error currently preventing our connection to
// Google Play services.
mSignInProgress = STATE_IN_PROGRESS;
startIntentSenderForResult(
mSignInIntent.getIntentSender(),
RC_SIGN_IN, null, 0, 0, 0
);
} catch (SendIntentException e) {
Log.i(TAG, "Sign in intent could not be sent: " + e.getLocalizedMessage());
// The intent was canceled before it was sent. Attempt to
// connect to
// get an updated ConnectionResult.
mSignInProgress = STATE_SIGN_IN;
mGoogleApiClient.connect();
}
}
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
switch (requestCode) {
case RC_SIGN_IN:
if (resultCode == RESULT_OK) {
// If the error resolution was successful we should continue
// processing errors.
mSignInProgress = STATE_SIGN_IN;
} else {
// If the error resolution was not successful or the user
// canceled,
// we should stop processing errors.
mSignInProgress = STATE_DEFAULT;
}
if (!mGoogleApiClient.isConnecting()) {
// If Google Play services resolved the issue with a dialog then
// onStart is not called so we need to re-attempt connection
// here.
mGoogleApiClient.connect();
}
break;
}
}
@Override
public void onConnectionSuspended(int cause) {
// The connection to Google Play services was lost for some reason.
// We call connect() to attempt to re-establish the connection or get a
// ConnectionResult that we can attempt to resolve.
mGoogleApiClient.connect();
}
private GoogleApiClient build_GoogleApiClient() {
// When we build the GoogleApiClient we specify where connected and
// connection failed callbacks should be returned, which Google APIs our
// app uses and which OAuth 2.0 scopes our app requests.
return new GoogleApiClient.Builder(this)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.addApi(Plus.API, null)
.addScope(Plus.SCOPE_PLUS_LOGIN)
.build();
}
private void onSignedOut() {
// Update the UI to reflect that the user is signed out.
mSignInButton.setEnabled(true);
mSignOutButton.setEnabled(false);
mRevokeButton.setEnabled(false);
mStatus.setText(R.string.status_signed_out);
}
}
答案 0 :(得分：13)
GoogleSignInApi的silentSignIn方法可用于检查 用户的缓存凭证的有效性。
我们可以使用GoogleSignInApi.silentSignIn（）方法检查登录凭据是否有效。
它返回一个OptionalPendingResult对象，用于检查凭证是否有效。如果凭证有效，OptionalPendingResult的isDone（）方法将返回true
然后可以使用get方法立即获得结果（如果可用）。
GoogleSignInApi的Android文档：
https://developers.google.com/android/reference/com/google/android/gms/auth/api/signin/GoogleSignInApi
OptionalPendingResult的Android文档：
https://developers.google.com/android/reference/com/google/android/gms/common/api/OptionalPendingResult
这里是用于检查凭据是否有效的代码。
OptionalPendingResult<GoogleSignInResult> opr = Auth.GoogleSignInApi.silentSignIn(google_api_client);
if (opr.isDone())
{
// If the user's cached credentials are valid, the OptionalPendingResult will be "done" and the GoogleSignInResult will be available instantly.
Log.d("TAG", "Got cached sign-in");
GoogleSignInResult result = opr.get();
handleSignInResult(result);
}
注意 - 该方法需要一个GoogleApiClient对象，因此请确保在验证之前连接了googleapiclient对象。
答案 1 :(得分：7)
正常连接MainActivity中的GoogleApiClient，但是在onConnectionFailed中而不是存储结果或解决错误启用登录按钮。当用户点击它时，启动您的LoginActivity，它也应该实现GoogleApiClient和相关接口，并从那里完成所有的ConnectionResult处理。
如果您创建一个基本活动来执行您的活动实施的GoogleApiClient设置，您可能会觉得更容易。在每个活动上启动GoogleApiClient连接是完全没问题的 - 它设计为以这种方式使用。
答案 2 :(得分：3)
我所做的是在SharedPreferences中存储一个布尔值（所以在应用程序完成时它会保留），并使用它来决定是否应该提供G +登录。
所以基本上你做了你正在做的事情，但是在你的MainActivity的onCreate方法中，你检查用户是否已经登录。如果它像往常一样继续活动。否则与教程
相同编辑：此外，如果用户尚未授权，我可能会隐藏撤销和注销按钮，因为它们将毫无用处。只有在有意义的情况下才显示它们，即如果用户已登录，