firebaseクラスっぽいやつ

firebaseCommunicator.java

package sample.hoge;

import java.io.FileInputStream;

import com.google.firebase.FirebaseApp;
import com.google.firebase.FirebaseOptions;

public class FirebaseCommunicator {
	FirebaseApp app;
	public void initialize(String jsonFileName, String url, String identifier) throws Exception {
		FileInputStream serviceAccount = new FileInputStream(jsonFileName);
		FirebaseOptions options = new FirebaseOptions.Builder().setServiceAccount(serviceAccount).setDatabaseUrl(url)
				.build();
		FirebaseApp.initializeApp(options, identifier);
		app = FirebaseApp.getInstance(identifier);
//		System.out.println(app);
	}
	public FirebaseApp getApp() {
		return app;
	}
}

gistfile1.txt

package sample.hoge;

import java.io.FileInputStream;

import com.google.firebase.FirebaseApp;
import com.google.firebase.FirebaseOptions;
import com.google.firebase.database.ChildEventListener;
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 App {
	static String JSON_FILE_NAME = "???.json";
	static String URL = "h???";

	public static void main(String[] args) throws Exception {
		FirebaseCommunicator sampleFc = new FirebaseCommunicator();
		sampleFc.initialize(JSON_FILE_NAME, URL, "sample");

		DatabaseReference reference = FirebaseDatabase.getInstance(sampleFc.getApp()).getReference("folder");
		System.out.println(reference.getKey());
		
		reference.limitToLast(1).addChildEventListener(new ChildEventListener() {
			public void onChildAdded(DataSnapshot dataSnapshot, String prevChildKey) {
				Object key = dataSnapshot.getKey();
				Object value = dataSnapshot.getValue();
				System.out.println("child event : " + key + " , " + value + " and " + prevChildKey);
			}

			public void onCancelled(DatabaseError arg0) {
			}

			public void onChildChanged(DataSnapshot arg0, String arg1) {
			}

			public void onChildMoved(DataSnapshot arg0, String arg1) {
			}

			public void onChildRemoved(DataSnapshot arg0) {
			}
		});

		reference.limitToLast(1).addValueEventListener(new ValueEventListener() {
			public void onDataChange(DataSnapshot dataSnapshot) {
				Object obj = dataSnapshot.getValue();
				System.out.println("value event : " + obj);
			}

			public void onCancelled(DatabaseError databaseError) {
				System.out.println("The read failed: " + databaseError.getCode());
			}
		});
		
		int counter = 0;
		while (true) {
			counter++;
			System.out.println("実行中です。");
			Thread.sleep(5000);
			if(counter % 3 == 2) {
				reference.push().setValue("クロウカード" + counter);
			}
		}

	}

}