我已为我的应用实施了facebook登录。成功登录后，将调用onSuccess（）回调。但是，当我从facebook注销时，虽然注销成功，但不会调用onCancel（）回调。在日志中，单击注销后会看到以下行：
01-24 17:22:07.801 952-952/? W/SurfaceFlinger: couldn't log to binary event log: overflow
我正在使用API 23.使用Android 6.0和Facebook SDK 4.6.0在模拟器上尝试过 以下是我的代码：
package com.example.ankur.pollutionandweathermonitor;
import android.Manifest;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Toast;
import com.facebook.AccessToken;
import com.facebook.CallbackManager;
import com.facebook.FacebookCallback;
import com.facebook.FacebookException;
import com.facebook.FacebookSdk;
import com.facebook.Profile;
import com.facebook.login.LoginResult;
import com.facebook.login.widget.LoginButton;
public class MainActivity extends AppCompatActivity {
//LoginButton and callbackManager are for facebook login
private LoginButton loginButton;
CallbackManager callbackManager;
/*firstName is to store the firstname of the logged in facebook user*/
private String firstName;
/*profile and accessToken are for to get the current session tokens of the logged in users*/
private Profile profile;
private AccessToken accessToken;
/*permissionStatus is to store the ACCESS_FINE_LOCATION permission of the user*/
private boolean permissionStatus;
/*EXTRA_MESSAGE_FIRSTNAME is to send the firstname of the logged in facebook user in the intent*/
public final static String EXTRA_MESSAGE_FIRSTNAME = "USERNAME";
/*EXTRA_MESSAGE_LOCATION_PERMISSION is to send the ACCESS_FINE_LOCATION permission value in the intent*/
public final static String EXTRA_MESSAGE_LOCATION_PERMISSION = "PERMISSION";
/*Logs generated in this class are accessed through the Tag LOGTAG*/
private String LOGTAG = MainActivity.class.getSimpleName();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//Initialize the facebook SDK for login
FacebookSdk.sdkInitialize(getApplicationContext());
callbackManager = CallbackManager.Factory.create();
setContentView(R.layout.activity_main);
//Call the CheckFacebookToken() function to see if there is a logged in user already.
//The function returns the firstname if there is a logged in user, else returns null
firstName = CheckFacebookToken();
if(firstName != null) {
//If there is an active current Session, then check if the user has granted the
// ACCESS_FINE_LOCATION permission. This check is only for Android >= 6.0
//For Android <6, the permission can be put in the AndroidMenifestFile
CheckLocationPermission();
}
//create the facebook login Button
loginButton = (LoginButton) findViewById(R.id.login_button);
try{
loginButton.setReadPermissions("user_friends");
loginButton.registerCallback(callbackManager, new FacebookCallback<LoginResult>() {
@Override
public void onSuccess(LoginResult loginResult) {
Log.v(LOGTAG, "successfully connected to facebook");
//After the login is successful, get the firstname of the logged in user
firstName = CheckFacebookToken();
//If there is an active current Session, then check if the user has granted the
// ACCESS_FINE_LOCATION permission. This check is only for Android >= 6.0
//For Android <6, the permission can be put in the AndroidMenifestFile
CheckLocationPermission();
}
@Override
public void onCancel() {
someCallback();
Log.v(LOGTAG, " connection to facebook cancelled");
}
@Override
public void onError(FacebookException exception) {
Toast.makeText(getApplicationContext(), "Fb Login Error", Toast.LENGTH_LONG);
Log.v(LOGTAG, "Error on connection to facebook");
}
});
}catch (Exception e){
Log.v(LOGTAG, "Error in the loginButton facebook");
e.printStackTrace();
}
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
}
//check if the user has granted the ACCESS_FINE_LOCATION permission.
// This check is only for Android >= 6.0. For Android <6, the permission can be put in the AndroidMenifestFile
protected void CheckLocationPermission(){
if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, 100);
}
else{
//Redirects the user to the Activity DisplayInformation
RedirectToDisplayInformation();
}
}
protected void someCallback(){
Log.v(LOGTAG, "logged out from facebook");
}
//The function CheckFacebookToken returns the firstname of the logged in facebook user, else returns null
protected String CheckFacebookToken(){
//Check if there is an active facebook session
String fName = null;
try{
accessToken = AccessToken.getCurrentAccessToken();
Log.v(LOGTAG, accessToken.getToken());
} catch (Exception e){
e.printStackTrace();
}
//If there is an Active facebook session, get the firstname and redirect user to the
//DisplayInformation Activity, send the username through the intent
if(accessToken != null) {
try {
profile = Profile.getCurrentProfile();
if(profile != null) {
fName = profile.getFirstName();
Log.v(LOGTAG, "There is an active session. The logged in user is " + fName);
}
}catch (Exception e){
e.printStackTrace();
}
}
else {
Log.v(LOGTAG, "No Active sessions found");
}
return fName;
}
//The function RedirectToDisplayInformation redirects the user to the Activity DisplayInformation
//The intent also sends the firstname of the logged in facebook user
protected void RedirectToDisplayInformation(){
Log.v(LOGTAG, "successfully called the function RedirectToDisplayInformation");
Intent intent = new Intent(this, DisplayInformation.class);
intent.putExtra(EXTRA_MESSAGE_LOCATION_PERMISSION, String.valueOf(permissionStatus));
intent.putExtra(EXTRA_MESSAGE_FIRSTNAME,firstName );
//startActivity(intent);
}
//This function is to call the callback functions of facebook after the login attempt
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
callbackManager.onActivityResult(requestCode, resultCode, data);
}
@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);
}
//The function onRequestPermissionResult is a callback to promt the user to either allow or deny the
//permissions. This function is significant only for Android >6
@Override
public void onRequestPermissionsResult(int requestCode,String permissions[], int[] grantResults) {
Log.v(LOGTAG, "onRequestPermissionResult");
switch (requestCode) {
case 100: {
// If request is cancelled, the result arrays are empty.
if (grantResults.length > 0
&& grantResults[0] == PackageManager.PERMISSION_GRANTED) {
permissionStatus = true;
Log.v(LOGTAG, "Permission Granted. Status is: " + String.valueOf(permissionStatus));
}
else {
permissionStatus = false;
Log.v(LOGTAG, "Permission Denied. Status is: " + String.valueOf(permissionStatus));
}
RedirectToDisplayInformation();
return;
}
}
}
}
答案 0 :(得分：1)
当您注销时，Profile和AccessToken将变为null，但不会调用onCancel。
希望这会有所帮助：）