詳解Flutter 調用 Android Native 的方法

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Flutter 調用 Android Native 的方法，是通過MethodChannel的方式來實現的:

在Android端：

  • 創建一個Class，實現FlutterPlugin和MethodCallHandler接口
  • 重寫onAttachedToEngine()，onDetachedFromEngine()，onMethodCall()
  • onAttachedToEngine()中，根據自定義的CHANNEL_NAME創建MethodChannel， onDetachedFromEngine中，釋放MethodChannel
  • onMethodCall中，通過自定義的METHOD_NAME，來響應Flutter中，invokeMethod對Native的通信，代碼如下
class MethodChannelPlugin : FlutterPlugin, MethodChannel.MethodCallHandler {

  private var methodChannel: MethodChannel? = null
  private var mNoteForFlutterListener: NoteForFlutterListener? = null

  companion object {
    private const val CHANNEL_NAME = "method_channel"
    private const val METHOD_NAME = "saveNote"
    val instance: MethodChannelPlugin by lazy(mode = LazyThreadSafetyMode.SYNCHRONIZED) {
      MethodChannelPlugin()
    }
  }

  override fun onAttachedToEngine(binding: FlutterPlugin.FlutterPluginBinding) {
    methodChannel = MethodChannel(binding.binaryMessenger, CHANNEL_NAME)
    methodChannel?.setMethodCallHandler(this)
  }

  override fun onDetachedFromEngine(binding: FlutterPlugin.FlutterPluginBinding) {
    methodChannel?.setMethodCallHandler(null)
    methodChannel = null
  }

  override fun onMethodCall(call: MethodCall, result: MethodChannel.Result) {
    if (call.method == METHOD_NAME) {
      val content = call.argument<String>("content")
      mNoteForFlutterListener?.sendData(content!!)
      result.success("success")
    } else {
      result.notImplemented()
    }
  }

  fun setListener(noteForFlutterListener: NoteForFlutterListener) {
    mNoteForFlutterListener = noteForFlutterListener
  }

在Flutter端：

  • 根據Native中定義的METHOD_NAME來創建MethodChannel
  • 通過MethodChannel.invokeMethod(METHOD_NAME,params)，參數METHOD_NAME為Native中定義的METHOD_NAME，params為傳遞的參數，就可以和Native進行通信瞭，在Native的onMethodCall方法中，通過call.method == METHOD_NAME來確定，Flutter是否調用的是Native中定義的METHOD_NAME的方法，代碼如下
class NoteMainFulState extends State<NoteMainFul> {
 //flutter 和 native 通信
 static const _methodMessageChannel = MethodChannel("method_channel");
 TextField textField;
 TextEditingController textEditingController;

 @override
 Widget build(BuildContext context) {
  return Scaffold(
   body: Container(
    margin: EdgeInsets.fromLTRB(20.0, 60.0, 20.0, 20.0),
    child: Column(
     children: [
      Container(
       child: Column(
        children: [
         textField = TextField(
          //去掉下劃線
          decoration: InputDecoration(border: InputBorder.none),
          enabled: true,
          controller: textEditingController = NoteTextEditingController(),
          keyboardType: TextInputType.multiline,
          textInputAction: TextInputAction.newline,
          maxLines: null,
         ),
         RichText(
          text: TextSpan(),
         ),
        ],
       ),
      ),
      Container(
       color: Colors.deepPurple,
       height: 50,
       child: Row(
        mainAxisAlignment: MainAxisAlignment.spaceEvenly,
        children: [
         GestureDetector(
          child: Icon(
           Icons.forward,
          ),
          onTap: clickOut,
         )
        ],
       ),
      )
     ],
    ),
   ),
  );
 }

 void clickOut() async {
  //調用native方法，返回首頁
  var content = textEditingController.text;
  Map<String, dynamic> map = {"content": content};
  var result = await _methodMessageChannel.invokeMethod("saveNote", map);
  print("result $result");
 }

以上就是Flutter 調用 Android Native 的方法的過程，有時間再分析下他們的實現原理
待續….
附，我當前的Flutter版本是 ：
Flutter 1.22.3 • channel stable • https://github.com/flutter/flutter
Framework • revision 8874f21e79 (3 months ago) • 2020-10-29 14:14:35 -0700
Engine • revision a1440ca392
Tools • Dart 2.10.3

 到此這篇關於詳解Flutter 調用 Android Native 的方法的文章就介紹到這瞭,更多相關Flutter 調用Android Native內容請搜索WalkonNet以前的文章或繼續瀏覽下面的相關文章希望大傢以後多多支持WalkonNet！

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