1. Flutter发布了其Android嵌入的新版本。这是负责将Flutter集成到Android应用程序中的Android代码。它包括类，如FlutterActivity，FlutterFragment，FlutterView，和FlutterEngine。Android v2嵌入包括对标准Android生命周期事件的支持，以及Flutter执行与Android UI的分离，这在Android v1嵌入中是缺少的。在开发v2 Android嵌入的过程中，很明显，现有的Flutter插件API不足以处理v2 Android嵌入的新功能。需要一个新的Android插件API。

2. 在旧的Android v1嵌入版本中，所有插件都在Android应用程序的一开始就进行了初始化和配置，并且只有一种Flutter体验。在v2嵌入中，我们不假设插件何时初始化，并且每个FlutterEngine插件必须初始化一次。因此，所有适用于Android的Flutter插件现在都必须支持实例化而不是静态初始化，并且它们必须支持与FlutterEngine进行连接和分离。以下代码示例演示了旧的v1插件初始化实现和新的v2插件初始化过程之间的区别。

旧插件初始化

class MyOldPlugin {
  public static void registerWith(PluginRegistrar registrar) {
    // Obtain any references that the plugin requires from the 
    // registrar.
    //
    // This plugin is now considered "initialized" and "attached" 
    // to a Flutter experience.
  }
}

新插件初始化

class MyNewPlugin implements FlutterPlugin {
  public MyNewPlugin() {
    // All Android plugin classes must support a no-args 
    // constructor. A no-arg constructor is provided by 
    // default without declaring one, but we include it here for 
    // clarity.
    //
    // At this point your plugin is instantiated, but it 
    // isn't attached to any Flutter experience. You should not 
    // attempt to do any work here that is related to obtaining 
    // resources or manipulating Flutter.
  }
  @override
  public void onAttachedToFlutterEngine(FlutterPluginBinding binding) {
    // Your plugin is now attached to a Flutter experience 
    // represented by the given FlutterEngine. 
    //
    // You can obtain the associated FlutterEngine with
    // binding.getFlutterEngine()
    //
    // You can obtain a BinaryMessenger with 
    // binding.getBinaryMessenger()
    // 
    // You can obtain the Application context with
    // binding.getApplicationContext()
    //
    // You cannot access an Activity here because this 
    // FlutterEngine is not necessarily displayed within an 
    // Activity. See the ActivityAware interface for more info.
  }
  @override
  public void onDetachedFromFlutterEngine(FlutterPluginBinding binding) {
    // Your plugin is no longer attached to a Flutter experience. 
    // You need to clean up any resources and references that you 
    // established in onAttachedToFlutterEngine().
  }
}

此外，你的插件不得依赖onAttachedToFlutterEngine（）中的Activity引用。仅仅因为你的插件已附加到Flutter体验上，并不意味着Flutter体验正在活动中显示。这是新旧插件API之间最重要的区别之一。在旧的v1插件API中，插件作者可能依赖于活动可立即且永久可用。这不再是事实。

有关更多信息，请参见https://medium.com/flutter/modern-flutter-plugin-development-4c3ee015cf5a