实战解析：Flutter 在 OpenHarmony 上的插件开发与系统能力调用

Dart (Flutter UI) 
   ↓ (MethodChannel)
C++ (Plugin Entrypoint)
   ↓ (NAPI)
ArkTS/JS (OpenHarmony System API via @ohos.batteryInfo)
   ↓
Kernel / HAL

flutter create --org com.example --template=plugin --platforms=ohos ohos_battery

ohos_battery/
├── lib/
│   └── ohos_battery.dart          # Dart 接口
├── ohos/
│   ├── src/main/cpp/              # C++ 桥接代码
│   │   ├── ohos_battery.cpp
│   │   └── CMakeLists.txt
│   └── src/main/js/               # JS 调用系统 API（临时方案）
│       └── battery_bridge.js
└── pubspec.yaml

import 'package:flutter/services.dart';

class OhosBattery {
  static const MethodChannel _channel =
      MethodChannel('com.example/ohos_battery');

  /// 获取电池电量（0~100）
  static Future<int> getBatteryLevel() async {
    final int? level = await _channel.invokeMethod('getBatteryLevel');
    return level ?? -1;
  }
}

#include "napi/native_api.h"
#include "napi/native_node_api.h"
#include <string>

// 模拟调用 JS Bridge（实际项目中可通过 JS Engine 执行 battery_bridge.js）
// 此处为简化，直接返回模拟值；真实场景需集成 JS 引擎或等待官方 C API

static napi_value GetBatteryLevel(napi_env env, napi_callback_info info) {
    napi_value result;
    // 假设通过某种方式从 OpenHarmony 获取到电量为 78%
    int32_t batteryLevel = 78;

    napi_create_int32(env, batteryLevel, &result);
    return result;
}

static napi_value Init(napi_env env, napi_value exports) {
    napi_property_descriptor desc = {
        "getBatteryLevel", nullptr, GetBatteryLevel, nullptr, nullptr, nullptr, napi_default, nullptr
    };
    napi_define_properties(env, exports, 1, &desc);
    return exports;
}

// 注册插件入口
EXTERN_C_START
void InitOhosBattery(napi_env env, napi_value exports) {
    Init(env, exports);
}
EXTERN_C_END

// battery_bridge.js
import batteryInfo from '@ohos.batteryInfo';

export function getBatteryLevelSync() {
  try {
    const info = batteryInfo.getBatteryInfoSync();
    return info.level; // 返回 0~100 的整数
  } catch (err) {
    console.error('Failed to get battery info:', err);
    return -1;
  }
}

// 使用 QuickJS 示例
JSContext* ctx = JS_NewContext();
JSValue val = JS_Eval(ctx, "getBatteryLevelSync()", ...);
int level = JS_ToInt32(ctx, val);

cmake_minimum_required(VERSION 3.18)
project(ohos_battery)

add_library(ohos_battery SHARED
    ohos_battery.cpp
)

target_include_directories(ohos_battery PRIVATE
    ${OHOS_SDK}/native/sysroot/usr/include
)

target_link_libraries(ohos_battery
    libace_napi.z.so
)

{
  "app": {
    "bundleName": "com.example.ohos_battery",
    "nativeLibs": ["libs/ohos_battery.so"]
  }
}

// main.dart
import 'package:flutter/material.dart';
import 'package:ohos_battery/ohos_battery.dart';

void main() => runApp(const MyApp());

class MyApp extends StatefulWidget {
  const MyApp({super.key});

  @override
  State<MyApp> createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  String _batteryLevel = 'Unknown';

  @override
  void initState() {
    super.initState();
    _getBatteryLevel();
  }

  Future<void> _getBatteryLevel() async {
    int level = await OhosBattery.getBatteryLevel();
    setState(() {
      _batteryLevel = 'Battery: $level%';
    });
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(title: const Text('OpenHarmony Battery Demo')),
        body: Center(child: Text(_batteryLevel)),
      ),
    );
  }
}