如何在android（Firebase）中维护用户会话

Question

在Android开发中我是初学者我最近跟着一个Android用户注册和登录的教程，每件事情都是正确的，但我找不到的一件事是android会话管理，所以请帮我这样做。

这是我的LoginActivity Source：

import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;



import android.app.ProgressDialog;
import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.design.widget.TextInputLayout;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;

import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.auth.AuthResult;
import com.google.firebase.auth.FirebaseAuth;

@SuppressWarnings("ConstantConditions")
public class LoginActivity extends AppCompatActivity {

    private TextInputLayout emailField;
    private TextInputLayout passwordField;
    private View btnLogin;
    private View btnRegister;
    private Button btnResetPassword;
    private ProgressDialog progressDialog;
    private FirebaseAuth auth;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_login);
        emailField = (TextInputLayout) findViewById(R.id.email_field);
        passwordField = (TextInputLayout) findViewById(R.id.password_field);
        btnLogin = findViewById(R.id.login);
        btnRegister = findViewById(R.id.register);
        btnResetPassword = (Button) findViewById(R.id.btn_reset_password);
        //Get Firebase auth instance
        auth = FirebaseAuth.getInstance();


        btnResetPassword.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                startActivity(new Intent(LoginActivity.this, ResetPasswordActivity.class));
                }
            });

        //go to Login Activity
        btnRegister.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent(LoginActivity.this, RegisterActivity.class);
                startActivity(intent);
                finish();
            }
        });



        btnLogin.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if (!Utils.hasText(emailField)) {
                    Utils.showToast(LoginActivity.this, "Please input your email");
                } else if (!Utils.hasText(passwordField)) {
                    Utils.showToast(LoginActivity.this, "Please input your password");
                } else {
                    //requesting Firebase server
                    showProcessDialog();
                    authenticateUser(Utils.getText(emailField), Utils.getText(passwordField));
                }
            }
        });
    }

    private void authenticateUser(String email, String password) {
        auth.signInWithEmailAndPassword(email, password)
                .addOnCompleteListener(LoginActivity.this, new OnCompleteListener<AuthResult>() {
                    @Override
                    public void onComplete(@NonNull Task<AuthResult> task) {
                        // When login failed
                        if (!task.isSuccessful()) {
                            Utils.showToast(LoginActivity.this, "Login error!");
                        } else {
                            //When login successful, redirect user to main activity
                            Intent intent = new Intent(LoginActivity.this, MainActivity.class);
                            startActivity(intent);
                            progressDialog.dismiss();
                            finish();
                        }
                    }
                });
    }

    private void showProcessDialog() {
        progressDialog = new ProgressDialog(this);
        progressDialog.setTitle("Login");
        progressDialog.setMessage("Logging in Firebase server...");
        progressDialog.show();
    }

    public void onBackPressed() {
        Intent a = new Intent(Intent.ACTION_MAIN);
        a.addCategory(Intent.CATEGORY_HOME);
        a.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        startActivity(a);
    }
}

这是Profile.java来源：

    public class Profile extends AppCompatActivity {

    private FirebaseAuth.AuthStateListener authListener;
    private FirebaseAuth auth;
    private ImageView imageView;
    private TextView email;
    private TextView name;
    private View btnLogOut;
    private TextView userId;


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

        name = (TextView) findViewById(R.id.displayed_name);
        email = (TextView) findViewById(R.id.email_field);
        btnLogOut = findViewById(R.id.logout);
        userId = (TextView) findViewById(R.id.user_id);
        imageView = (ImageView) findViewById(R.id.user_photo);

        //get firebase auth instance
        auth = FirebaseAuth.getInstance();

        //get current user
        FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser();
        setDataToView(user);

        //add a auth listener
        authListener = new FirebaseAuth.AuthStateListener() {
            @SuppressLint("SetTextI18n")
            @Override
            public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
                Log.d("Profile", "onAuthStateChanged");
                FirebaseUser user = firebaseAuth.getCurrentUser();
                if (user != null) {
                    setDataToView(user);

                    //loading image by Picasso
                    if (user.getPhotoUrl() != null) {
                        Log.d("Profile", "photoURL: " + user.getPhotoUrl());
                        Picasso.with(Profile.this).load(user.getPhotoUrl()).into(imageView);
                    }
                } else {
                    //user auth state is not existed or closed, return to Login activity
                    startActivity(new Intent(Profile.this, LoginActivity.class));
                    finish();
                }
            }
        };

        //Signing out
        btnLogOut.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                auth.signOut();

            }
        });
    }

    @SuppressLint("SetTextI18n")
    private void setDataToView(FirebaseUser user) {
        email.setText("User Email: " + user.getEmail());
        name.setText("User name: " + user.getDisplayName());
        userId.setText("User id: " + user.getUid());
    }

    @Override
    public void onStart() {
        super.onStart();
        auth.addAuthStateListener(authListener);
    }

    @Override
    public void onStop() {
        super.onStop();
        if (authListener != null) {
            auth.removeAuthStateListener(authListener);
        }
    }
}