android - Android Studio：如何使用片段正确登录 Firebase
问题描述
我搜索了几个 StackOverflow 问题，例如：
显示 Firebase 数据库条目时 Android 应用程序崩溃
是否有必要在 Android Firebase 的每个活动中添加一个 AuthStateListener？
应用程序因 java.lang.NullPointerException 而崩溃
FirebaseAuth.getCurrentUser() 返回空值
android-java.lang.NullPointerException 使用 getCurrentUser firebase auth
使用 FirebaseAuthentication 时应用程序在首次启动期间崩溃
什么是 NullPointerException，我该如何解决？
最后是关于我面临的问题的最接近的问题：
在片段上的 getCurrentUser().getUid() 上获取空对象引用
我还没有找到答案。在最后一个链接中，StackOverflow 成员解释说发生NullPointerException是因为应用程序忽略了从 MainActivity 到 LoginActivity 的重定向，getCurrentUser().getUid() == null并执行了发生NullPointerException的 ChatFragment 。
我的应用程序一开始在模拟器上遇到了这种问题，但不知何故它在模拟器上运行良好。
但是现在，我尝试在我的物理设备中安装该应用程序并且该应用程序崩溃了。我收到NullPointerException因为用户尚未登录。
我的应用类似于 WhatsApp ChatApp。它具有带有两个片段的滑动 TabLayout。我的应用程序启动 MainActivity，它应该在首次使用应用程序的情况下将 AppUser 重定向到 LoginActivity。
这是我的 MainActivity
public class MainPageActivity extends AppCompatActivity implements GroupListAdapter.DataChangeListener {
public static final int PERMISSIONS_MULTIPLE_REQUEST = 123;
private Toolbar mToolBar;
private ViewPager mViewPager;
private TabLayout mTabLayout;
private TabsAccessAdapter mTabsAcessAdapter;
private FirebaseAuth mAuth;
private DatabaseReference RootRef;
private String currentUserID;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main_page);
FirebaseApp.initializeApp(this);
mAuth = FirebaseAuth.getInstance();
RootRef = FirebaseDatabase.getInstance().getReference();
mToolBar = (Toolbar) findViewById(R.id.main_page_toolbar);
setSupportActionBar(mToolBar);
getSupportActionBar().setTitle("MyApp");
mViewPager = (ViewPager) findViewById(R.id.tabs_pager);
mTabsAcessAdapter = new TabsAccessAdapter(getSupportFragmentManager());
mViewPager.setAdapter(mTabsAcessAdapter);
mTabLayout = (TabLayout) findViewById(R.id.tablayout);
mTabLayout.setupWithViewPager(mViewPager);
getPermissions();
}
private void getPermissions() {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
requestPermissions(new String[]{Manifest.permission.WRITE_CONTACTS,Manifest.permission.READ_CONTACTS,
Manifest.permission.WRITE_EXTERNAL_STORAGE,Manifest.permission.READ_EXTERNAL_STORAGE},PERMISSIONS_MULTIPLE_REQUEST);
}
}
@Override
protected void onStart() {
super.onStart();
Log.i("debinf mainpage", "onStart");
FirebaseAuth.getInstance().addAuthStateListener(new FirebaseAuth.AuthStateListener() {
@Override
public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
FirebaseUser currentUser = firebaseAuth.getCurrentUser();
if (currentUser == null) {
//Here is the place to redirect the AppUser to LoginActivity
sendUserToLoginActivity();
}else {
VerifyUserExistance();
}
}
});
}
private void VerifyUserExistance() {
String currentUserID = mAuth.getCurrentUser().getUid();
RootRef.child("user").child(currentUserID).addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
Toast.makeText(MainPageActivity.this, "Bem vindo(a)!", Toast.LENGTH_SHORT).show();
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
}
// Dealing with MENU > starts here
@Override
public boolean onCreateOptionsMenu(Menu menu) {
super.onCreateOptionsMenu(menu);
getMenuInflater().inflate(R.menu.options_menu,menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
super.onOptionsItemSelected(item);
if (item.getItemId() == R.id.main_logout_option) {
mAuth.signOut();
sendUserToLoginActivity();
}
if (item.getItemId() == R.id.main_settings_option) {
//sendUserToSettingsActivity();
Toast.makeText(this, "Settings from MainAct", Toast.LENGTH_SHORT).show();
}
return false;
}
private void sendUserToLoginActivity() {
Intent loginIntent = new Intent(MainPageActivity.this,LoginActivity.class);
loginIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
startActivity(loginIntent);
}
@Override
public void onDataSetChanged(String groupKeyFromSender, boolean addToCall) {
String tag = "android:switcher:" + R.id.tabs_pager + ":" + 1;
CallFragment rf = (CallFragment) getSupportFragmentManager().findFragmentByTag(tag);
rf.getDataFromGroupFragment(groupKeyFromSender, addToCall);
}
}
这是我的 LoginActivity，它应该在第一次使用时由 MainActivity 调用，但事实并非如此。
public class LoginActivity extends AppCompatActivity {
private EditText mPhoneNumber, mCode;
private Button mSend;
private PhoneAuthProvider.OnVerificationStateChangedCallbacks mCallbacks;
String mVerificationId;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
FirebaseApp.initializeApp(this);
userIsLoggedIn();
mPhoneNumber = findViewById(R.id.phoneNumber);
mCode = findViewById(R.id.code);
mSend = findViewById(R.id.send);
mSend.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (mVerificationId != null) {
verifyPhoneNumberWithCode();
} else {
startPhoneNumberVerification();
}
}
});
mCallbacks = new PhoneAuthProvider.OnVerificationStateChangedCallbacks() {
@Override
public void onVerificationCompleted(PhoneAuthCredential phoneAuthCredential) {
sighInWithPhoneAuthCredential(phoneAuthCredential);
}
@Override
public void onVerificationFailed(FirebaseException e) {
}
@Override
public void onCodeSent(String verificationId, PhoneAuthProvider.ForceResendingToken forceResendingToken) {
super.onCodeSent(verificationId, forceResendingToken);
mVerificationId = verificationId;
mSend.setText("Enviar codigo");
}
};
}
private void verifyPhoneNumberWithCode(){
PhoneAuthCredential credential = PhoneAuthProvider.getCredential(mVerificationId, mCode.getText().toString());
sighInWithPhoneAuthCredential(credential);
}
private void sighInWithPhoneAuthCredential(PhoneAuthCredential phoneAuthCredential) {
FirebaseAuth.getInstance().signInWithCredential(phoneAuthCredential).addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
@Override
public void onComplete(@NonNull Task<AuthResult> task) {
if (task.isSuccessful()) {
//userIsLoggedIn();
final FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser();
// I think add child named user and inside other child named userId = user.getUid()
if (user != null) {
// Do not forget to add database implementation in the gradle (module app)
final DatabaseReference mUserDB = FirebaseDatabase.getInstance().getReference().child("user").child(user.getUid());
mUserDB.addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
if (!dataSnapshot.exists()) {
// if user has never loged in, add a new user
Map<String, Object> userMap = new HashMap<>();
userMap.put("phone", user.getPhoneNumber());
//userMap.put("name", user.getPhoneNumber());
userMap.put("name", "babaloo");
mUserDB.updateChildren(userMap);
}
userIsLoggedIn();
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
}
}
}
});
}
private void userIsLoggedIn() {
FirebaseAuth.getInstance().addAuthStateListener(new FirebaseAuth.AuthStateListener() {
@Override
public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
FirebaseUser user = firebaseAuth.getCurrentUser();
if (user != null) {
startActivity(new Intent(getApplicationContext(), MainPageActivity.class));
finish();
return;
}
}
});
}
private void startPhoneNumberVerification() {
PhoneAuthProvider.getInstance().verifyPhoneNumber(
mPhoneNumber.getText().toString(),60,
TimeUnit.SECONDS, this, mCallbacks);
}
}
这里是发生NullPointerException的 GroupFragment 的 onCreateView 。
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
view = inflater.inflate(R.layout.group_fragment, container, false);
groupTablePath = getContext().getFilesDir().getPath()+"/GroupDataBase/";
rootPath = Environment.getExternalStorageDirectory() + "/";
mAuth = FirebaseAuth.getInstance();
currentUser = mAuth.getCurrentUser().getUid();
GroupRef = FirebaseDatabase.getInstance().getReference().child("Group");
UserRef = FirebaseDatabase.getInstance().getReference().child("user");
StoreRef = FirebaseStorage.getInstance().getReference();
FloatingActionButton findUser = (FloatingActionButton) view.findViewById(R.id.addContact);
findUser.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
startActivity(new Intent(view.getContext(), FindUserActivity.class));
}
});
//getPermissions();
CreateRootFolder();
initializeRecyclerView();
loadGroupListDatabase();
populateTeamTableInternet();
OwnerGroupUploadClientListTable();
updateClientListInternet();
// Inflate the layout for this fragment
return view;
}
这部分错误
at com.example.aliton.myapp.Fragments.GroupFragment.onCreateView(GroupFragment.java:107)
对应GroupFragment的onCreateView中的这行代码：
currentUser = mAuth.getCurrentUser().getUid();
这是致命错误：
02-09 20:24:10.950 24837-24837/com.example.aliton.myapp E/AndroidRuntime: FATAL EXCEPTION: main
java.lang.NullPointerException
at com.example.aliton.myapp.Fragments.GroupFragment.onCreateView(GroupFragment.java:107)
at android.support.v4.app.Fragment.performCreateView(Fragment.java:2439)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1460)
at android.support.v4.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManager.java:1784)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1852)
at android.support.v4.app.BackStackRecord.executeOps(BackStackRecord.java:802)
at android.support.v4.app.FragmentManagerImpl.executeOps(FragmentManager.java:2625)
at android.support.v4.app.FragmentManagerImpl.executeOpsTogether(FragmentManager.java:2411)
at android.support.v4.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManager.java:2366)
at android.support.v4.app.FragmentManagerImpl.execSingleAction(FragmentManager.java:2243)
at android.support.v4.app.BackStackRecord.commitNowAllowingStateLoss(BackStackRecord.java:654)
at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:146)
at android.support.v4.view.ViewPager.populate(ViewPager.java:1244)
at android.support.v4.view.ViewPager.populate(ViewPager.java:1092)
at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1622)
at android.view.View.measure(View.java:15294)
at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:665)
at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:447)
at android.view.View.measure(View.java:15294)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4818)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:143)
at android.view.View.measure(View.java:15294)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4818)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1421)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:712)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:605)
at android.view.View.measure(View.java:15294)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4818)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at android.view.View.measure(View.java:15294)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4818)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1421)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:712)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:605)
at android.view.View.measure(View.java:15294)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4818)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2432)
at android.view.View.measure(View.java:15294)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1872)
at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1115)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1296)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1013)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4245)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:725)
at android.view.Choreographer.doCallbacks(Choreographer.java:555)
at android.view.Choreographer.doFrame(Choreographer.java:525)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:711)
at android.os.Handler.handleCallback(Handler.java:615)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:153)
at android.app.ActivityThread.main(ActivityThread.java:5076)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:790)
at com.
我很感激任何帮助。
解决方案
这里有3个问题
- 身份验证侦听器是异步的，因此可以使用片段适配器创建竞争条件
- 您在 onCreate 之后在 onStart 上附加了 auth 侦听器，此时片段已经附加
- 如果用户未登录，则您将主逻辑屏幕作为入口点，然后它将返回登录。它应该是向后的，你应该使登录允许用户前进到下一个活动。
要修复 1 和 2，您将不得不重构代码。
要修复数字 3，您应该在清单中将登录设置为默认活动。
要修复您现在拥有的内容，请将其添加到 main 的 onCreate 方法中
FirebaseApp.initializeApp(this);
mAuth = FirebaseAuth.getInstance();
RootRef = FirebaseDatabase.getInstance().getReference();
if (mAuth.getCurrentUser() == null) return;
返回该点将使代码跳转到 onStary ，在那里您有 auth 侦听器使您的逻辑正常工作
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