Question

我正在制作一个具有firebase登录的简单聊天应用程序。一切正常，但令我困扰的是如果用户登录，启动该应用程序后它会显示一段时间的登录活动，然后重定向到第二秒每次都不好看。以下是用于更好理解的屏幕截图

这是在应用打开1-2秒后每次都会显示的活动，即使用户已登录

这是登录页面

我想要的是，如果用户登录并打开应用程序，那么他应该直接看到第二个活动

MainActivity（登录活动）

package com.example.fireapp;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.os.Bundle;
import android.text.TextUtils;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ProgressBar;
import android.widget.Toast;

import com.google.android.gms.auth.api.signin.GoogleSignIn;
import com.google.android.gms.auth.api.signin.GoogleSignInAccount;
import com.google.android.gms.auth.api.signin.GoogleSignInClient;
import com.google.android.gms.auth.api.signin.GoogleSignInOptions;
import com.google.android.gms.common.SignInButton;
import com.google.android.gms.common.api.ApiException;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.auth.AuthCredential;
import com.google.firebase.auth.AuthResult;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;
import com.google.firebase.auth.GoogleAuthProvider;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.ValueEventListener;

public class MainActivity extends AppCompatActivity {

    private EditText emailEditText;
    private EditText passwordEditText;
    private Button loginButton;
    private FirebaseAuth mAuth;
    private FirebaseAuth.AuthStateListener mAuthListner;
    private Button signInButton;
    private SignInButton googleButton;
    private GoogleSignInClient mGoogleSignInClient;
    private int RC_SIGN_IN = 1;
    private String TAG = "Info";
    private ProgressBar progressBar;
    int flag = 0;
    DatabaseReference reference;

    //firebase
    FirebaseUser user;
    String userId;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        emailEditText = findViewById(R.id.emailEditText);
        passwordEditText = findViewById(R.id.passwordEditText);
        loginButton = findViewById(R.id.signUpButton);
        signInButton = findViewById(R.id.signInButton);
        googleButton = findViewById(R.id.googleButton);
        progressBar = findViewById(R.id.progressBar);
        mAuth = FirebaseAuth.getInstance();
        mAuthListner = new FirebaseAuth.AuthStateListener() {
            @Override
            public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
                if (firebaseAuth.getCurrentUser() != null && flag != 1) {
                    startActivity(new Intent(MainActivity.this, Main2Activity.class));
                    finish();
                }

            }
        };

        loginButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                progressBar.setVisibility(View.VISIBLE);
                login();
            }
        });
        signInButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                progressBar.setVisibility(View.GONE);
                startActivity(new Intent(MainActivity.this, accountActivity.class));
                // finish();
            }
        });
        GoogleSignInOptions gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
                .requestIdToken(getString(R.string.default_web_client_id))
                .requestEmail()
                .build();
        mGoogleSignInClient = GoogleSignIn.getClient(this, gso);
        googleButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                flag = 1;
                signIn();
            }
        });
    }

    @Override
    protected void onStart() {
        super.onStart();
        mAuth.addAuthStateListener(mAuthListner);
    }

    private void login() {
        String email = emailEditText.getText().toString();
        String password = passwordEditText.getText().toString();
        if (TextUtils.isEmpty(email) || TextUtils.isEmpty(password)) {
            progressBar.setVisibility(View.GONE);
            Toast.makeText(this, "Fields are Empty", Toast.LENGTH_SHORT).show();
        } else {
            mAuth.signInWithEmailAndPassword(email, password).addOnCompleteListener(new OnCompleteListener<AuthResult>() {
                @Override
                public void onComplete(@NonNull Task<AuthResult> task) {
                    if (!task.isSuccessful()) {
                        progressBar.setVisibility(View.GONE);
                        Toast.makeText(MainActivity.this, "Sign in unsuccessful!!", Toast.LENGTH_SHORT).show();
                    }
                }
            });
        }
    }

    private void signIn() {
        Intent signInIntent = mGoogleSignInClient.getSignInIntent();
        startActivityForResult(signInIntent, RC_SIGN_IN);
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        // Result returned from launching the Intent from GoogleSignInApi.getSignInIntent(...);
        if (requestCode == RC_SIGN_IN) {
            Task<GoogleSignInAccount> task = GoogleSignIn.getSignedInAccountFromIntent(data);
            try {
                // Google Sign In was successful, authenticate with Firebase
                GoogleSignInAccount account = task.getResult(ApiException.class);
                firebaseAuthWithGoogle(account);
            } catch (ApiException e) {
                // Google Sign In failed, update UI appropriately
                Log.w(TAG, "Google sign in failed", e);
                // ...
            }
        }
    }

    private void firebaseAuthWithGoogle(GoogleSignInAccount acct) {
        Log.d(TAG, "firebaseAuthWithGoogle:" + acct.getId());
        AuthCredential credential = GoogleAuthProvider.getCredential(acct.getIdToken(), null);
        mAuth.signInWithCredential(credential)
                .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
                    @Override
                    public void onComplete(@NonNull Task<AuthResult> task) {
                        if (task.isSuccessful()) {
                            // Sign in success, update UI with the signed-in user's information
                            Log.d(TAG, "signInWithCredential:success");
                            user = mAuth.getCurrentUser();
                            userId = user.getUid();
                            reference = FirebaseDatabase.getInstance().getReference("User").child(userId);
                            reference.addListenerForSingleValueEvent(new ValueEventListener() {
                                @Override
                                public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                                    if (dataSnapshot.exists()) {
                                        startActivity(new Intent(MainActivity.this, Main2Activity.class));
                                        Toast.makeText(MainActivity.this, "Google Sign in Successful", Toast.LENGTH_SHORT).show();
                                        finish();

                                    } else {
                                        startActivity(new Intent(MainActivity.this, DetailsActivity.class));
                                        Toast.makeText(MainActivity.this, "Google Sign in Successful", Toast.LENGTH_SHORT).show();
                                        finish();
                                    }
                                }

                                @Override
                                public void onCancelled(@NonNull DatabaseError databaseError) {

                                }
                            });

                        } else {
                            // If sign in fails, display a message to the user.
                            Log.w(TAG, "signInWithCredential:failure", task.getException());

                        }
                    }
                });
    }
}

Main2Activity

package com.example.fireapp;

import android.content.Intent;
import android.os.Bundle;

import com.bumptech.glide.Glide;
import com.example.fireapp.model.Users;
import com.firebase.ui.auth.AuthUI;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;
import com.google.android.material.navigation.NavigationView;
import androidx.annotation.NonNull;
import androidx.appcompat.app.ActionBarDrawerToggle;
import androidx.core.view.GravityCompat;
import androidx.drawerlayout.widget.DrawerLayout;
import androidx.appcompat.app.AppCompatActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.TextView;
import android.widget.Toast;
import androidx.appcompat.widget.Toolbar;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.ValueEventListener;

import de.hdodenhof.circleimageview.CircleImageView;

public class Main2Activity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener {

    private DrawerLayout drawerLayout;
    private NavigationView navigationView;
    private View headerView;
    private TextView usernameText;
    private TextView emailText;
    private CircleImageView userImage;
    private FirebaseUser firebaseUser;
    private DatabaseReference reference;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);

        //toolbar
        Toolbar toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        getSupportActionBar().setTitle("fireApp");

        //navigation drawer
        drawerLayout = findViewById(R.id.drawer_layout);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(this, drawerLayout, toolbar,
                R.string.navigation_drawer_open,
                R.string.navigation_drawer_close);
        drawerLayout.addDrawerListener(toggle);
        toggle.syncState();


        //user details inside navigation drawer
        navigationView = findViewById(R.id.nav_view);
        navigationView.setNavigationItemSelectedListener(this);
        headerView = navigationView.getHeaderView(0);
        usernameText = headerView.findViewById(R.id.usernameText);
        userImage = headerView.findViewById(R.id.userImage);
        emailText = headerView.findViewById(R.id.userEmail);
        setUserDetails();
        if(savedInstanceState==null) {
            getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,
                    new chatFragment()).commit();
            navigationView.setCheckedItem(R.id.nav_chat);
        }

    }

    private void setUserDetails() {
        firebaseUser = FirebaseAuth.getInstance().getCurrentUser();
        reference = FirebaseDatabase.getInstance().getReference("User").child(firebaseUser.getUid());
        reference.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
               Users user= dataSnapshot.getValue(Users.class);
                try {
                usernameText.setText(user.getUsername());
                emailText.setText(firebaseUser.getEmail());

                    if (user.getImageUrl().equals("default")) {
                        userImage.setImageResource(R.mipmap.ic_launcher);
                    } else {
                        Glide.with(getApplicationContext()).load(user.getImageUrl()).into(userImage);
                    }
                }
                catch (Exception e){

                }
            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {

            }
        });
    }

    @Override
    public boolean onNavigationItemSelected(@NonNull MenuItem menuItem) {
        switch(menuItem.getItemId()){
            case R.id.nav_chat:
                getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,
                        new chatFragment()).commit();
                break;
            case R.id.nav_profile:
                getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,
                        new profileFragment()).commit();
                break;
            case R.id.nav_feed:
                getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,
                        new feedFragment()).commit();
                break;
            case R.id.nav_share:
                Toast.makeText(this, "Share!", Toast.LENGTH_SHORT).show();
                break;
            case R.id.nav_feedback:
                Toast.makeText(this, "Feedback!", Toast.LENGTH_SHORT).show();
                break;
        }


        drawerLayout.closeDrawer(GravityCompat.START);
        return true;
    }

    @Override
    public void onBackPressed() {

        if (drawerLayout.isDrawerOpen(GravityCompat.START)) {
            drawerLayout.closeDrawer(GravityCompat.START);
        } else {
            super.onBackPressed();
        }

    }

    //3 dots menu
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        super.onCreateOptionsMenu(menu);
        getMenuInflater().inflate(R.menu.main_menu, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(@NonNull MenuItem item) {
        super.onOptionsItemSelected(item);
        if (item.getItemId() == R.id.logout) {
            AuthUI.getInstance()
                    .signOut(Main2Activity.this)
                    .addOnCompleteListener(new OnCompleteListener<Void>() {

                        @Override
                        public void onComplete(@NonNull Task<Void> task) {

                            startActivity(new Intent(Main2Activity.this, MainActivity.class));
                            finish();

                        }
                    });
            return true;
        } else
            return false;
    }

}

请帮助

Answer 1

一个简单的解决方案是创建一个SharedPreferences

假设您为isLoggedIn创建了一个首选项，然后在打开的第一个活动中，在onCreate中要做的第一件事就是检查用户是否为isLoggedIn。然后从那里可以执行if..else intent MainActivity或LoginActivity。

Answer 2

尝试在用户登录后完成活动

finish();

然后在用户注销后将其带回LoginActivity

Answer 3

尝试

从外部服务进行登录的过程不是立即进行的，我建议您使用异步任务，这样在完成登录过程时，您不会发生上述情况

public class MainActivity extends AppCompatActivity {
    ProgressDialog dialog;
    ....
    ....
@Override
    protected void onCreate(Bundle savedInstanceState) {
        loginButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                new loginTask().execute(true);
            }
        });
    }

}

class loginTask extends AsyncTask<Boolean, Void, String> {

        @Override
        protected void onPreExecute() {
            dialog = ProgressDialog.show(MainActivity.this, "", "Loading", true);
            super.onPreExecute();
        }

        @Override
        protected void onPostExecute(String s) {
            dialog.dismiss();

            /** Redirect to main2 class **/
            Intent intent = new Intent(MainActivity.this, Main2Activity.class);
            intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_SINGLE_TOP);
            startActivity(intent);
            finish();
            super.onPostExecute(s);
        }

        @Override
        protected String doInBackground(Boolean... booleans) {
        /** Your code **/
              String email = emailEditText.getText().toString();
              String password = passwordEditText.getText().toString();
              if (TextUtils.isEmpty(email) || TextUtils.isEmpty(password)) {
                  progressBar.setVisibility(View.GONE);
                  Toast.makeText(this, "Fields are Empty",Toast.LENGTH_SHORT).show();
              } else {
                mAuth.signInWithEmailAndPassword(email,password).addOnCompleteListener(new OnCompleteListener<AuthResult>() {
                @Override
                public void onComplete(@NonNull Task<AuthResult> task) {
                    if (!task.isSuccessful()) {
                        progressBar.setVisibility(View.GONE);
                        Toast.makeText(MainActivity.this, "Sign in unsuccessful!!", Toast.LENGTH_SHORT).show();
                    }
                }
            });
          }

        }
}

Answer 4

您可以像这样分配侦听器

if(mFirebaseAuth.getCurrentUser() == null) 
      startActivity(new Intent(LaunchScreen.this, LoginScreen.class));
else
      startActivity(new Intent(LaunchScreen.this, MainActivity.class));
finish();

Answer 5

在意图之后尝试使用finish（），此活动将被关闭，因此也将变得无法访问。

每次启动应用程序时都会打开主要活动

5 个答案: