如何从 Firebase 数据库中读取数据？

请告诉我如何正确地从 Firebase 读取数据。我根据文档工作，我做了所有这样的事情，但它显示“数据库权限被拒绝”。

package com.example.strike.myapplication;

import android.os.Bundle;
import android.support.annotation.NonNull;
import android.widget.Toast;

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 stanford.androidlib.SimpleActivity;

public class LoginActivity extends SimpleActivity {
    private FirebaseDatabase database;
    private DatabaseReference myRef;

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

        database = FirebaseDatabase.getInstance();
        myRef = database.getReference("/animal/PLaNGFwshzOhzys2VhOP");

        myRef.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                String value =  dataSnapshot.getValue(String.class);
                Toast.makeText(getApplicationContext(), value, Toast.LENGTH_SHORT).show();
            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {
                Toast.makeText(getApplicationContext(), "Value is: " + databaseError, Toast.LENGTH_SHORT).show();
            }
        });
    }

}

规则

service cloud.firestore {

    match /databases/{database}/documents {
    match /{document=**} {
       allow read, write;
      }
    }

}