获取颤振插件中的活动参考

Question

当我创建flutter插件时，默认情况下插件类中有两个方法：

override fun onAttachedToEngine(flutterPluginBinding: FlutterPlugin.FlutterPluginBinding)

和

fun registerWith(registrar: Registrar)

文件上的评论说：鼓励在onAttachedToEngine和registerWith之间共享逻辑，以保持它们的功能等效。根据用户的项目，只调用onAttachedToEngine或registerWith中的一个。onAttachedToEngine或registerWith必须在同一个类中定义

现在，我需要从这里开始另一个活动，使用activity.startActivityForResult（）。可以使用registrar.activity（）在注册表中获取对活动的引用。如何在方法onAttachedToEngine（flutterPluginBind： FlutterPlugin. FlutterPluginBind）中执行此操作？




Answer 1

通过实现ActivityAware接口

https://www.codenong.com/jseb7df49fdfb1/

package com.example.fluttertoast

import android.app.Activity
import android.content.Context
import android.widget.Toast
import androidx.annotation.NonNull;

import io.flutter.embedding.engine.plugins.FlutterPlugin
import io.flutter.embedding.engine.plugins.activity.ActivityAware
import io.flutter.embedding.engine.plugins.activity.ActivityPluginBinding
import io.flutter.plugin.common.MethodCall
import io.flutter.plugin.common.MethodChannel
import io.flutter.plugin.common.MethodChannel.MethodCallHandler
import io.flutter.plugin.common.MethodChannel.Result
import io.flutter.plugin.common.PluginRegistry.Registrar

/** FluttertoastPlugin */
class FluttertoastPlugin: FlutterPlugin, MethodCallHandler, ActivityAware {
  private lateinit var channel : MethodChannel
  private lateinit var activity:Activity
  private lateinit var context: Context

  override fun onAttachedToEngine(@NonNull flutterPluginBinding: FlutterPlugin.FlutterPluginBinding) {
    channel = MethodChannel(flutterPluginBinding.flutterEngine.dartExecutor, "fluttertoast")
    channel.setMethodCallHandler(this)
    this.context = flutterPluginBinding.applicationContext
  }

  companion object {
    @JvmStatic
    fun registerWith(registrar: Registrar) {
      val channel = MethodChannel(registrar.messenger(), "fluttertoast")
      channel.setMethodCallHandler(FluttertoastPlugin())
    }
  }

  override fun onMethodCall(@NonNull call: MethodCall, @NonNull result: Result) {
    if (call.method == "getPlatformVersion") {
      Toast.makeText(activity,"Hello!",Toast.LENGTH_SHORT).show()
      result.success("Android ${android.os.Build.VERSION.RELEASE}")
    } else {
      result.notImplemented()
    }
  }

  override fun onDetachedFromEngine(@NonNull binding: FlutterPlugin.FlutterPluginBinding) {
    channel.setMethodCallHandler(null)
  }
  override fun onDetachedFromActivity() {}
  override fun onReattachedToActivityForConfigChanges(binding: ActivityPluginBinding) {
    onAttachedToActivity(binding)
  }
  override fun onAttachedToActivity(binding: ActivityPluginBinding) {
    this.activity = binding.activity
  }
  override fun onDetachedFromActivityForConfigChanges() {}
}

Answer 2

匿名用户

注：

您可以通过实现ActivityAware接口获得对activity的引用，但如果您使用setMethodCallHandler（…） onAttachToEngine（）方法onAttachToActivity（）中的code>，并且您永远无法访问活动

看看下面的例子

不起作用的部分：在下面的示例中，从不调用onAttachToActivity（）

class AndroidLongTaskPlugin : FlutterPlugin, ActivityAware {
  private var activity: FlutterActivity? = null

  

  override fun onAttachedToEngine(@NonNull flutterPluginBinding: FlutterPlugin.FlutterPluginBinding) {
    //activity is null here 
    //also onAttachToActivity will never be called because we are calling setMethodHandler here
    channel = MethodChannel(binaryMessenger, CHANNEL_NAME)
    channel.setMethodCallHandler { call, result ->
        //our code
    }

  }

  override fun onDetachedFromEngine(@NonNull binding: FlutterPlugin.FlutterPluginBinding) {
    channel?.setMethodCallHandler(null)
  }

  override fun onAttachedToActivity(binding: ActivityPluginBinding) {
    activity = binding.activity as FlutterActivity
  }

  //rest of the methods
}

下面是一个工作示例：

class MyPlugin : FlutterPlugin, ActivityAware {
  private var activity: FlutterActivity? = null
  private var binaryMessenger: BinaryMessenger? = null

  override fun onAttachedToEngine(@NonNull flutterPluginBinding: FlutterPlugin.FlutterPluginBinding) {
    binaryMessenger = flutterPluginBinding.binaryMessenger
  }

  override fun onDetachedFromEngine(@NonNull binding: FlutterPlugin.FlutterPluginBinding) {
    Log.d("DART/NATIVE", "onDetachedFromEngine")
    channel?.setMethodCallHandler(null)
  }

  override fun onAttachedToActivity(binding: ActivityPluginBinding) {
    Log.d("DART/NATIVE", "onAttachedToActivity")
    activity = binding.activity as FlutterActivity
    //here we have access to activity
    //also make sure to setMethodCallHandler here
    channel.setMethodCallHandler { call, result ->
        //our code
    }
  }

  //rest of the methods
}

Answer 3

在这里找到了解决方案
实现ActivityAware，其方法之一是

 override fun onAttachedToActivity(binding: ActivityPluginBinding) {
    this.activity = binding.activity;
  }