如何检查用户是否已在firebase身份验证和firebase实时数据库中的数据之间注册和匹配数据？

Question

这是我第一次在StackOverflow中提问。 所以，我想在这个论坛上分享一个问题。 我已经注册了一个帐户进行firebase身份验证并在Firebase Realtime-Database上记录。 你可以看到这些照片

https://i.ibb.co/TcqDhF7/image.png

https://i.ibb.co/Zc1YnLY/image.png

问题出在登录上。 当我登录时，我预计Firebase可以匹配身份验证和数据库之间的数据，但这是相反的。 问题是Can Firebase可以在身份验证和数据库上的数据记录之间匹配用户数据吗？

我试过像这样修改我的Login Activity类

LoginActivity.java

package id.co.dolansemarang.loginfirebaseds;

import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

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;
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;

public class LoginActivity extends AppCompatActivity {
    Button btnLogin;
    EditText edtEmailLogin, edtPasswordLogin;
    FirebaseAuth firebaseAuthLogin;
    DatabaseReference userRefLogin;
    FirebaseUser curUser;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);
        btnLogin = findViewById(R.id.btn_login);
        edtEmailLogin = findViewById(R.id.edt_email_login);
        edtPasswordLogin = findViewById(R.id.edt_password_login);
        firebaseAuthLogin = FirebaseAuth.getInstance();
        curUser = FirebaseAuth.getInstance().getCurrentUser();

        btnLogin.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                final String email = edtEmailLogin.getText().toString();
                final String password = edtPasswordLogin.getText().toString();

                if (email.isEmpty()) {
                    Toast.makeText(LoginActivity.this, "Masukkan email", Toast.LENGTH_SHORT).show();
                } else {
                    if (password.isEmpty()) {
                        Toast.makeText(LoginActivity.this, "Masukkan password", Toast.LENGTH_SHORT).show();
                    } else {
                        firebaseAuthLogin.signInWithEmailAndPassword(email, password).addOnCompleteListener(LoginActivity.this, new OnCompleteListener<AuthResult>() {
                            @Override
                            public void onComplete(@NonNull Task<AuthResult> task) {
                                if (task.isSuccessful()) {

                                    userRefLogin = FirebaseDatabase.getInstance().getReference().child("Users").child(curUser.getUid());
                                    userRefLogin.addListenerForSingleValueEvent(new ValueEventListener() {
                                        @Override
                                        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                                            if (dataSnapshot.exists()) {
                                                //ambil data password
                                                String passwordFromFirebase = dataSnapshot.child("password").getValue().toString();
                                                //validasi password dengan password di edit text
                                                if (password.equals(passwordFromFirebase)) {
//                                                    menyimpan data ke local storage (handphone)
//                                                    SharedPreferences sharedPreferences = getSharedPreferences(USERNAME_KEY, MODE_PRIVATE);
//                                                    SharedPreferences.Editor editor = sharedPreferences.edit();
//                                                    editor.putString(username_key, etUsername.getText().toString());
//                                                    editor.apply();
                                                    startActivity(new Intent(LoginActivity.this, MainActivity.class));

                                                } else {
                                                    Toast.makeText(LoginActivity.this, "Pasword tidak cocok", Toast.LENGTH_SHORT).show();
                                                }

                                            } else {
                                                Toast.makeText(LoginActivity.this, "Username tidak terdaftar", Toast.LENGTH_SHORT).show();
                                            }
                                        }

                                        @Override
                                        public void onCancelled(@NonNull DatabaseError databaseError) {
                                            Toast.makeText(LoginActivity.this, "Pasword tidak cocok", Toast.LENGTH_SHORT).show();
                                        }
                                    });

                                } else {
                                    Toast.makeText(LoginActivity.this, "Pasword tidak cocok", Toast.LENGTH_SHORT).show();
                                    Log.w("Pesan", "Gagal Masul");
                                }

                            }
                        });
                    }
                }

            }
        });
    }
}

我希望firebase可以检查两者的匹配密码和电子邮件数据，这样当我登录应用程序时，Firebase会检查Firebase身份验证和数据库上的电子邮件和密码。 我需要帮助 ：（

Answer 1

在这里您可以找到已注册的电子邮件ID： -

    private void loginUserWithFirebase(String email, String password) {
           firebaseAuthLogin.signInWithEmailAndPassword(email, password)
                   .addOnCompleteListener(getActivity(), new OnCompleteListener<AuthResult>() {
                       @Override
                       public void onComplete(@NonNull Task<AuthResult> task) {
                           progressDialog.dismiss();
                           if (task.isSuccessful()) {
                               // here is user registered
                               startActivity(new Intent(LoginActivity.this, MainActivity.class));
                           }
                           else{
                               // here if your is not registered or any elese error will show
                               Toast.makeText(getContext(), "" + task.getException().toString(), Toast.LENGTH_SHORT).show();
                           }
                       }
                   });
       }

Answer 2

登录后，获取用户Uid然后使用该id调用realTime数据库，如果datasnapshot为null，那么用户还没有注册，否则你可以检索他已经注册的用户。 我是这样做的：

 DatabaseReference ref = FirebaseDatabase.getInstance().getReference().child("users/"+uid);
    ref.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {

            //Log.d("dataSnapShotValue",""+dataSnapshot.getValue());
            if (dataSnapshot.getValue()!=null){
              // User exist
            }else{
              //  user dosn't exist
            }
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {
            System.out.println("The read failed: " + databaseError.getCode());
        }
    });

Answer 3

> firebase will  check it Self User is Authenticated or not so you  can not
  to check Manually.




 private void loginUserWithFirebase(String email, String password) {
           firebaseAuthLogin.signInWithEmailAndPassword(email, password)
                   .addOnCompleteListener(getActivity(), new OnCompleteListener<AuthResult>() {
                       @Override
                       public void onComplete(@NonNull Task<AuthResult> task) {

                           if (task.isSuccessful()) {

                               startActivity(new Intent(LoginActivity.this, MainActivity.class));



 }
                           else{

                               Toast.makeText(getContext(), "" + task.getException().toString(), Toast.LENGTH_SHORT).show();
                           }
                       }
                   });
       }