Flutter调原生View

之前写过通过MethodChannel来调取原生方法。https://www.jianshu.com/p/6b677ff3350e
但是这次是直接在Flutter里面调用一个android view。

一、Flutter项目中嵌入单个的Android View，步骤如下：

• 首先找到flutter项目下的android目录，点击包名下面的MainActivity，在编辑器的右上角有一个Open forEditing in Android studio 按钮，点击它可以进入纯android的项目中。

  
  android studio
• 在包名下创建一个原生view，代码如下

package com.example.flutter_demo

import android.content.Context
import android.view.View
import android.widget.TextView
import io.flutter.plugin.common.BinaryMessenger
import io.flutter.plugin.platform.PlatformView
class MyFlutterView(context: Context,messager : BinaryMessenger,
viewId: Int,argus: Map<String,Any>) : PlatformView{
    var  text : TextView =  TextView(context)
    init {
        text.text = "原生的textvieww"
    }
    override fun getView(): View {
        return text
    }

    override fun dispose() {
    }

}

• 在创建一个PlatformViewFactory，把原生view提供出去。代码如下

package com.example.flutter_demo

import android.content.Context
import io.flutter.plugin.common.BinaryMessenger
import io.flutter.plugin.common.StandardMessageCodec
import io.flutter.plugin.platform.PlatformView
import io.flutter.plugin.platform.PlatformViewFactory

class MyFlutterViewFactory(private val messager : BinaryMessenger) : PlatformViewFactory(StandardMessageCodec.INSTANCE) {
    override fun create(context: Context?, viewId: Int, args: Any?): PlatformView {
        return MyFlutterView(context!!, messager,viewId,args as Map<String,Any>)
    }

}

• 在创建一个FlutterPlugin,用来注册PlatformViewFactory，代码如下

package com.example.flutter_demo

import io.flutter.embedding.engine.plugins.FlutterPlugin

class MyPlugin : FlutterPlugin{
    override fun onAttachedToEngine(binding: FlutterPlugin.FlutterPluginBinding) {
        var binaryMessenger = binding.binaryMessenger
        binding.platformViewRegistry.registerViewFactory( "plugins.flutter.io/custom_platform_view",
        MyFlutterViewFactory(binaryMessenger))
    }
    companion object{
        @JvmStatic
        fun registerWith(registry: io.flutter.plugin.common.PluginRegistry.Registrar){
            registry.platformViewRegistry().registerViewFactory("plugins.flutter.io/custom_platform_view",
                    MyFlutterViewFactory(registry.messenger()))
        }
    }

    override fun onDetachedFromEngine(binding: FlutterPlugin.FlutterPluginBinding) {
    }

}

• 最后在MainActivity里面添加插件，代码如下

package com.example.flutter_demo

import io.flutter.embedding.android.FlutterActivity
import io.flutter.embedding.engine.FlutterEngine

class MainActivity: FlutterActivity() {
    
    
    override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
        super.configureFlutterEngine(flutterEngine)
        flutterEngine.plugins.add(MyPlugin())
    }
}

到此为止，android端的代码完成。再看下flutter端怎么调用android view

• 判断一下平台，然后跟flutter一样调用android view，代码如下

getwidget7(){
  if(defaultTargetPlatform == TargetPlatform.android){
    return AndroidView(viewType: "plugins.flutter.io/custom_platform_view",creationParams: {"ss":333},
    creationParamsCodec: StandardMessageCodec(),);
  }
}

其中viewType和原生里面保持一致，creationParams是给原生传递参数的。
直接运行就可以实现在flutter里面使用android view。tip：注意使用真机，我在使用模拟器的时候跑不起来。

调用原生view可以和调用原生方法一起用。