我正在尝试从名为“用户”的 Firestore 集合中检索所有文档,但收到一条错误消息。我也尝试检索单个文档,但遇到了同样的错误。
数据库连接 | 数据库.java
public Firestore db;
public Database() throws IOException {
// Use a service account
try {
InputStream serviceAccount = new FileInputStream("./serviceAccount.json");
GoogleCredentials credentials = GoogleCredentials.fromStream(serviceAccount);
FirebaseOptions options = FirebaseOptions.builder()
.setCredentials(credentials)
.setDatabaseUrl("https://riskgameverycool.firebaseio.com/")
.build();
FirebaseApp.initializeApp(options);
System.out.println("Connection GREAT Success!");
} catch(Exception e) {
// Block of code to handle errors
e.printStackTrace();
System.out.println("Connection Failed.");
}
}
Database.java:
public void getAllUsers() {
try {
// asynchronously retrieve all documents
ApiFuture<QuerySnapshot> future = db.collection("users").get();
// future.get() blocks on response
List<QueryDocumentSnapshot> documents = future.get().getDocuments();
for (QueryDocumentSnapshot document : documents) {
System.out.println(document.getId() + " => " + document.toObject(User.class));
}
} catch(Exception e) {
e.printStackTrace();
System.out.println("Query messed up.");
}
}
火库:
正如错误消息所说,您的db
字段永远不会被初始化。您可能想在Database()
方法中这样做:
db = FirestoreDatabase.getInstance();
另请参阅有关初始化 Firestore的 Firebase 文档。
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