[英]Not able to add data to firebase realtime database from java admin sdk
[英]Get information from Firebase Realtime Database with Firebase Admin SDK
我试图从Firebase实时数据库中获取一些信息但没有成功。 我不知道我做错了什么。 我也尝试了doc的例子但它们没有用。 这是我的代码和我的firebase db结构:
Topics.java:
public class Topics {
private String name;
public Topics() {
}
public Topics(String name) {
this.name = name;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
Main.java
public static void main(String[] args) {
// TODO Auto-generated method stub
FileInputStream serviceAccount;
FirebaseOptions options = null;
try {
serviceAccount = new FileInputStream(".//...");
options = new FirebaseOptions.Builder()
.setCredentials(GoogleCredentials.fromStream(serviceAccount))
.setDatabaseUrl("...")
.build();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch(IOException e) {
e.printStackTrace();
}
FirebaseApp.initializeApp(options);
String topics = getDatafromFirebase();
System.out.println("Everything right!");
}
private static String getDatafromFirebase() {
CountDownLatch done = new CountDownLatch(1);
StringBuilder b = new StringBuilder();
DatabaseReference dbRef = FirebaseDatabase.getInstance()
.getReference();
dbRef.child("topics").addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot snapshot) {
// TODO Auto-generated method stub
if(snapshot.exists()) {
for(DataSnapshot s:snapshot.getChildren()) {
Topics t = s.getValue(Topics.class);
b.append(t.getName());
b.append(" ");
done.countDown();
}
}
else {
b.append("No existe ");
done.countDown();
}
}
@Override
public void onCancelled(DatabaseError error) {
// TODO Auto-generated method stub
b.append("Error: "+error.getDetails());
done.countDown();
}
});
try {
done.await();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return b.toString();
}
我等待CountDownLatch
超过5+
分钟,我认为它足以触发它。 另外,重要提示:我已成功通过firebase云消息传递消息,因此我认为这不是凭据的问题。
我使用相同的数据库结构对我的数据库运行代码,我可以肯定地说我能够从数据库中获取信息。
如果我完全删除topics
子树,则仅触发onDataChange
断点。 即。 在你的情况下一个空的数据库。
我怀疑你的数据库网址或私钥JSON。
package fireb;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.concurrent.CountDownLatch;
import com.google.auth.oauth2.GoogleCredentials;
import com.google.firebase.FirebaseApp;
import com.google.firebase.FirebaseOptions;
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 Fireb {
public static void main(String[] args) {
// TODO Auto-generated method stub
FileInputStream serviceAccount;
FirebaseOptions options = null;
try {
serviceAccount = new FileInputStream("C:\\key\\testapp-f0fe2-firebase-adminsdk-4po4a-5ce6c60b81.json");
options = new FirebaseOptions.Builder()
.setCredentials(GoogleCredentials.fromStream(serviceAccount))
.setDatabaseUrl("https://testapp-f0fe2.firebaseio.com")
.build();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch(IOException e) {
e.printStackTrace();
}
FirebaseApp.initializeApp(options);
String topics = getDatafromFirebase();
System.out.println(topics);
System.out.println("Everything right!");
}
private static String getDatafromFirebase() {
CountDownLatch done = new CountDownLatch(1);
StringBuilder b = new StringBuilder();
DatabaseReference dbRef = FirebaseDatabase.getInstance()
.getReference();
dbRef.child("topics").addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot snapshot) {
// TODO Auto-generated method stub
if(snapshot.exists()) {
for(DataSnapshot s:snapshot.getChildren()) {
Topics t = s.getValue(Topics.class);
b.append(t.getName());
b.append(" ");
}
done.countDown();
}
else {
b.append("No existe ");
done.countDown();
}
}
@Override
public void onCancelled(DatabaseError error) {
// TODO Auto-generated method stub
b.append("Error: "+error.getDetails());
done.countDown();
}
});
try {
done.await();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return b.toString();
}
}
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