Flutter入门进阶之旅（二十）Flutter插件开发

class FlutterCalcPlugin : MethodCallHandler {
    companion object {
        @JvmStatic
        fun registerWith(registrar: Registrar) {
            val channel = MethodChannel(registrar.messenger(), "flutter_calc_plugin")
            channel.setMethodCallHandler(FlutterCalcPlugin())
        }
    }

    override fun onMethodCall(call: MethodCall, result: Result) {
        if (call.method == "getPlatformVersion") {
            result.success("Android ${android.os.Build.VERSION.RELEASE}")
        } else if (call.method == "getResult") {
            var a = call.argument<Int>("a")
            var b = call.argument<Int>("b")
            result.success((a!! + b!!).toString())
        } else {
            result.notImplemented()
        }
    }
}
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class FlutterCalcPlugin {
  static const MethodChannel _channel =
      const MethodChannel('flutter_calc_plugin');

  static Future<String> getplatformVersion async {
    final String version = await _channel.invokeMethod('getPlatformVersion');
    return version;
  }

  /**
   *计算两个数的和
   */
  static Future<String>  getResult(int a, int b) async {
    Map<String, dynamic> map = {"a": a, "b": b};
    String result = await _channel.invokeMethod("getResult", map);
    print(result+"----------aa--");
    return result;
  }
}
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#本地插件引入
  flutter_calc_plugin:
    path: plugin/flutter_calc_plugin
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  #从github上引入插件依赖
  flutter_calc_plugin:
    git:
     url:
      https://github.com/xiedong11/flutter_calc_plugin.git
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import 'package:flutter/material.dart';
import 'dart:async';

import 'package:flutter/services.dart';
import 'package:flutter_calc_plugin/flutter_calc_plugin.dart';

void main() => runApp(MyApp());

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  String _platformVersion = 'Unknown';
  String addResult = '';
  TextEditingController _addNumber1Controller,_addNumber2Controller;

  @override
  void initState() {
    super.initState();
    _addNumber1Controller = TextEditingController();
    _addNumber2Controller = TextEditingController();
  }

  Future<void> getAddResult() async {
    int addNumber1= int.parse(_addNumber1Controller.value.text);
    int addNumber2=int.parse(_addNumber2Controller.value.text);

    String result = '';
    try {
      result = await FlutterCalcPlugin.getResult(addNumber2, addNumber1);
    } on PlatformException {
      result = '未知错误';
    }
    setState(() {
      addResult = result;
    });
  }

  Future<void> initPlatformState() async {
    String platformVersion;

    try {
      platformVersion = await FlutterCalcPlugin.platformVersion;
    } on PlatformException {
      platformVersion = 'Failed to get platform version.';
    }

    if (!mounted) return;

    setState(() {
      _platformVersion = platformVersion;
    });
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('插件示例'),
        ),
        body: Center(
            child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            MaterialButton(
              color: Colors.amber,
              child: Text("获取系统版本"),
              onPressed: () {
                initPlatformState();
              },
            ),
            Text('当前系统版本 : $_platformVersion\n'),
            SizedBox(height: 30),
            Text("加法计算器"),
            Row(
              mainAxisAlignment: MainAxisAlignment.center,

              children: <Widget>[
                SizedBox(
                  width: 80,
                  child: TextField(
                    controller: _addNumber1Controller,
                    keyboardType: TextInputType.number,
                  ),
                ),
                Text("  +  ",style: TextStyle(fontSize: 26),),
                SizedBox(
                  width: 80,
                  child: TextField(
                    controller: _addNumber2Controller,
                    keyboardType: TextInputType.number,
                  ),
                ),
                Text("  = ",style: TextStyle(fontSize: 26),),
              ],
            ),
            SizedBox(height: 30),
            MaterialButton(
              color: Colors.amber,
              child: Text("结果等于"),
              onPressed: () {
                getAddResult();
              },
            ),
            Text(addResult),
          ],
        )),
      ),
    );
  }
}
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