在android中从firebase中检索数据(微调)

dependencies {
    // Firebase Realtime Database
    implementation 'com.google.firebase:firebase-database:20.0.0'
    // Firebase Authentication (如果需要身份验证)
    implementation 'com.google.firebase:firebase-auth:21.0.1'
    // 其他Firebase服务的依赖项
    // ...
}

<manifest>
    <!-- 添加网络访问权限 -->
    <uses-permission android:name="android.permission.INTERNET" />

    <application>
        <!-- 添加Firebase应用配置 -->
        <meta-data
            android:name="com.google.firebase.messaging.default_notification_channel_id"
            android:value="@string/default_notification_channel_id" />
        <meta-data
            android:name="com.google.firebase.messaging.default_notification_icon"
            android:resource="@drawable/ic_notification_icon" />

        <!-- 添加Firebase服务 -->
        <service
            android:name="com.google.firebase.messaging.FirebaseMessagingService"
            android:exported="false">
            <intent-filter>
                <action android:name="com.google.firebase.MESSAGING_EVENT" />
            </intent-filter>
        </service>
    </application>
</manifest>

import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;

public class MainActivity extends AppCompatActivity {
    private DatabaseReference mDatabase;

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

        // 初始化Firebase数据库引用
        mDatabase = FirebaseDatabase.getInstance().getReference();
    }
}

// 读取数据
mDatabase.child("users").child(userId).addListenerForSingleValueEvent(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        // 处理数据快照
        User user = dataSnapshot.getValue(User.class);
        // 对数据进行操作
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {
        // 处理错误
    }
});