Flutter 与原生交互总结，Android开发揭秘

在Flutter中与Android原生代码进行交互时，通常需要使用平台通道（Platform Channel）。以下是一个简化的例子，展示了如何从Flutter发送消息到Android原生并获取返回值：

首先，在Flutter端创建一个方法来发送消息：

// Flutter端
const platform = MethodChannel('samples.flutter.dev/battery');
 
Future<String> getBatteryInfo() async {
  String batteryLevel;
  try {
    final int result = await platform.invokeMethod('getBatteryLevel');
    batteryLevel = 'Battery level at $result% .';
  } on PlatformException catch (e) {
    batteryLevel = "Failed to get battery level: '${e.message}'.";
  }
  return batteryLevel;
}

然后，在Android原生端实现对应的接口：

// Android原生端
public class MainActivity extends FlutterActivity {
    private static final String CHANNEL = "samples.flutter.dev/battery";
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        GeneratedPluginRegistrant.registerWith(this);
 
        new MethodChannel(getFlutterView(), CHANNEL).setMethodCallHandler(
            (call, result) -> {
                // 假设我们只处理一个方法: getBatteryLevel
                if (call.method.equals("getBatteryLevel")) {
                    int batteryLevel = getBatteryLevel();
                    result.success(batteryLevel);
                } else {
                    result.notImplemented();
                }
            }
        );
    }
 
    private int getBatteryLevel() {
        // 获取电池电量的逻辑
        IntentFilter ifilter = new IntentFilter(Intent.ACTION_BATTERY_CHANGED);
        Intent batteryStatus = getApplicationContext().registerReceiver(null, ifilter);
 
        int status = batteryStatus != null ? batteryStatus.getIntExtra(BatteryManager.EXTRA_STATUS, -1) : -1;
        boolean isCharging = status == BatteryManager.BATTERY_STATUS_CHARGING ||
                             status == BatteryManager.BATTERY_STATUS_FULL;
 
        int level = batteryStatus != null ? batteryStatus.getIntExtra(BatteryManager.EXTRA_LEVEL, -1) : -1;
        int scale = battery