从活动的onCreate中已在运行的服务中获取数据

Intent serviceIntent = new Intent(this, MyService.class);
startService(serviceIntent);

public int onStartCommand(Intent intent, int flags, int startId) {
    // 执行后台任务获取数据
    // ...
    return START_STICKY;
}

// 在服务中发送广播
Intent dataIntent = new Intent("com.example.DATA_RECEIVED");
dataIntent.putExtra("data", yourData);
sendBroadcast(dataIntent);

private BroadcastReceiver dataReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        if (intent.getAction().equals("com.example.DATA_RECEIVED")) {
            String data = intent.getStringExtra("data");
            // 处理接收到的数据
            // ...
        }
    }
};

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

    // 注册广播接收器
    IntentFilter filter = new IntentFilter("com.example.DATA_RECEIVED");
    registerReceiver(dataReceiver, filter);
}