Flutter Google Maps渲染器热重启重复初始化异常求助

我使用google_maps_flutter_android: ^2.6.0尝试启用Flutter Google Maps的最新地图渲染器，初始代码如下：

main() async {
  ...
  
  AndroidMapRenderer mapRenderer = AndroidMapRenderer.platformDefault;

  final GoogleMapsFlutterPlatform mapsImplementation =
    GoogleMapsFlutterPlatform.instance;
  if (mapsImplementation is GoogleMapsFlutterAndroid) {
    WidgetsFlutterBinding.ensureInitialized();
    mapRenderer = await mapsImplementation.initializeWithRenderer(AndroidMapRenderer.latest);

  ...
  runApp(MyApp);
}

首次运行正常，但官方文档明确说明：

The renderer must be requested before creating GoogleMap instances, as the renderer can be initialized only once per application context.
（译文：渲染器必须在创建GoogleMap实例前请求，每个应用上下文仅能初始化一次渲染器。）

因此每次热重启时，都会抛出异常：

PlatformException (PlatformException(Renderer already initialized, Renderer initialization called multiple times, null, null))

我尝试用try-catch捕获异常，但仍会抛出异常导致应用暂停，修改后的代码如下：

main() async {
  ...
  
  AndroidMapRenderer mapRenderer = AndroidMapRenderer.platformDefault;

  try {
    final GoogleMapsFlutterPlatform mapsImplementation =
      GoogleMapsFlutterPlatform.instance;
    if (mapsImplementation is GoogleMapsFlutterAndroid) {
      WidgetsFlutterBinding.ensureInitialized();
       mapRenderer = await mapsImplementation.initializeWithRenderer(AndroidMapRenderer.latest);
    }
  } catch (e) {
    log(e.toString());
  }

  ...
  runApp(MyApp);
}

请问有没有办法让这段初始化代码仅执行一次，即使热重启也不重复运行？

方法1：检查当前渲染器状态再初始化 #

利用GoogleMapsFlutterAndroid提供的getRenderer()方法，先获取当前已生效的渲染器，仅当它不是最新版时才执行初始化操作：

main() async {
  // 必须先初始化绑定，确保异步操作正常执行
  WidgetsFlutterBinding.ensureInitialized();
  AndroidMapRenderer mapRenderer = AndroidMapRenderer.platformDefault;

  final GoogleMapsFlutterPlatform mapsImplementation =
      GoogleMapsFlutterPlatform.instance;
  if (mapsImplementation is GoogleMapsFlutterAndroid) {
    // 获取当前已初始化的渲染器
    final currentRenderer = await mapsImplementation.getRenderer();
    if (currentRenderer != AndroidMapRenderer.latest) {
      try {
        mapRenderer = await mapsImplementation.initializeWithRenderer(AndroidMapRenderer.latest);
      } catch (e) {
        log("渲染器初始化失败: $e");
      }
    } else {
      // 已使用最新渲染器，直接复用
      mapRenderer = currentRenderer;
    }
  }

  runApp(const MyApp());
}

方法2：用持久化存储标记初始化状态 #

使用SharedPreferences存储初始化成功的标记，因为持久化存储在热重启后不会丢失：

import 'package:shared_preferences/shared_preferences.dart';
import 'package:flutter/foundation.dart';
import 'package:google_maps_flutter_android/google_maps_flutter_android.dart';
import 'package:google_maps_flutter_platform_interface/google_maps_flutter_platform_interface.dart';

main() async {
  WidgetsFlutterBinding.ensureInitialized();
  final prefs = await SharedPreferences.getInstance();
  // 定义持久化标记的key
  const String initializedKey = 'has_initialized_latest_renderer';
  AndroidMapRenderer mapRenderer = AndroidMapRenderer.platformDefault;

  final GoogleMapsFlutterPlatform mapsImplementation =
      GoogleMapsFlutterPlatform.instance;
  if (mapsImplementation is GoogleMapsFlutterAndroid) {
    // 检查是否已初始化过最新渲染器
    bool hasInitialized = prefs.getBool(initializedKey) ?? false;
    if (!hasInitialized) {
      try {
        mapRenderer = await mapsImplementation.initializeWithRenderer(AndroidMapRenderer.latest);
        // 标记初始化成功
        await prefs.setBool(initializedKey, true);
      } catch (e) {
        log("渲染器初始化失败: $e");
      }
    } else {
      // 已初始化，直接获取当前渲染器
      mapRenderer = await mapsImplementation.getRenderer();
    }
  }

  runApp(const MyApp());
}

方法3：修复try-catch的作用范围 #

你之前的try-catch未生效，可能是因为WidgetsFlutterBinding.ensureInitialized()放在了if块内，导致异步操作环境未准备好。将binding初始化移到main函数最开头，并确保try-catch覆盖整个初始化逻辑：

main() async {
  WidgetsFlutterBinding.ensureInitialized();
  AndroidMapRenderer mapRenderer = AndroidMapRenderer.platformDefault;

  try {
    final GoogleMapsFlutterPlatform mapsImplementation =
        GoogleMapsFlutterPlatform.instance;
    if (mapsImplementation is GoogleMapsFlutterAndroid) {
      mapRenderer = await mapsImplementation.initializeWithRenderer(AndroidMapRenderer.latest);
    }
  } on PlatformException catch (e) {
    // 明确捕获平台异常
    if (e.code == 'Renderer already initialized') {
      // 若已初始化，直接获取当前渲染器
      final mapsImplementation = GoogleMapsFlutterPlatform.instance as GoogleMapsFlutterAndroid;
      mapRenderer = await mapsImplementation.getRenderer();
    } else {
      log("未知异常: $e");
    }
  } catch (e) {
    log("其他异常: $e");
  }

  runApp(const MyApp());
}

内容的提问来源于stack exchange，提问作者rhnzal