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詳解Flutter 調(diào)用 Android Native 的方法

更新時(shí)間：2021年01月22日 11:43:16 作者：zzzyplove

這篇文章主要介紹了詳解Flutter 調(diào)用 Android Native 的方法，文中通過示例代碼介紹的非常詳細(xì)，對(duì)大家的學(xué)習(xí)或者工作具有一定的參考學(xué)習(xí)價(jià)值，需要的朋友們下面隨著小編來一起學(xué)習(xí)學(xué)習(xí)吧

Flutter 調(diào)用 Android Native 的方法，是通過MethodChannel的方式來實(shí)現(xiàn)的:

在Android端：

創(chuàng)建一個(gè)Class，實(shí)現(xiàn)FlutterPlugin和MethodCallHandler接口
重寫onAttachedToEngine()，onDetachedFromEngine()，onMethodCall()
onAttachedToEngine()中，根據(jù)自定義的CHANNEL_NAME創(chuàng)建MethodChannel， onDetachedFromEngine中，釋放MethodChannel
onMethodCall中，通過自定義的METHOD_NAME，來響應(yīng)Flutter中，invokeMethod對(duì)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(jù)Native中定義的METHOD_NAME來創(chuàng)建MethodChannel
通過MethodChannel.invokeMethod(METHOD_NAME,params)，參數(shù)METHOD_NAME為Native中定義的METHOD_NAME，params為傳遞的參數(shù)，就可以和Native進(jìn)行通信了，在Native的onMethodCall方法中，通過call.method == METHOD_NAME來確定，F(xiàn)lutter是否調(diào)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(diào)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(diào)用 Android Native 的方法的過程，有時(shí)間再分析下他們的實(shí)現(xiàn)原理
待續(xù)....
附，我當(dāng)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

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