flutter methodchannel调用原生方法,实现原生插件

在获取手机电量,屏幕信息等,都需要flutter 调用原生实现,这部分flutter 官方已经帮我们实现好了,对于部分功能,需要自己实现, 步骤如下


# 创建一个 flutter 应用,使用 as 打开 android 目录, MainActivity 代码如下

package com.example.flutter_app;

import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;

import java.util.Map;

import io.flutter.app.FlutterActivity;
import io.flutter.plugin.common.MethodCall;
import io.flutter.plugin.common.MethodChannel;
import io.flutter.plugins.GeneratedPluginRegistrant;

public class MainActivity extends FlutterActivity {

  private static final String CHANNEL = "demo.gawkat.com/info";

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    GeneratedPluginRegistrant.registerWith(this);

    new MethodChannel(getFlutterView(), CHANNEL).setMethodCallHandler(new MethodChannel.MethodCallHandler() {
      @Override
      public void onMethodCall(MethodCall methodCall, MethodChannel.Result result) {

        final Map<String, Object> arguments = methodCall.arguments();

        if (methodCall.method.equals("getMessage")) {
           result.success("Android say hi."+ ((String) arguments.get("from")));
        }
//        openWebPage("http://www.bitying.com");
      }
    });
  }

  public void openWebPage(String url) {
    Uri webpage = Uri.parse(url);
    Intent intent = new Intent(Intent.ACTION_VIEW, webpage);
    if (intent.resolveActivity(getPackageManager()) != null) {
      startActivity(intent);
    }

  }
}



# ios 端 appDelegate.m

#include "AppDelegate.h"
#include "GeneratedPluginRegistrant.h"

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application
    didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
  [GeneratedPluginRegistrant registerWithRegistry:self];
  // Override point for customization after application launch.
    
    FlutterViewController* controller = (FlutterViewController*)self.window.rootViewController;

    FlutterMethodChannel* channel = [FlutterMethodChannel
                                     methodChannelWithName:@"demo.gawkat.com/info"
                                     binaryMessenger:controller
                                    ];


    [channel setMethodCallHandler:^(FlutterMethodCall* call, FlutterResult result) {
        NSString *from = call.arguments[@"from"];

        if([@"getMessage" isEqualToString:call.method]) {
            NSString *messgae = @"IOS says greetings";
            NSString *returnMessage = [messgae stringByAppendingString:from];
            result(returnMessage);
        }
    }];
    

    
  return [super application:application didFinishLaunchingWithOptions:launchOptions];
}

@end


# flutter 端 main.dart 编写如下代码

  static const platform = const MethodChannel('demo.gawkat.com/info');

  String _message = 'No message yet...';

  Future<String> _getMessage() async {
    var sendMap = <String, dynamic> {
     'from' : 'boy',
    };
    String value;
    try {
      value = await platform.invokeMethod('getMessage', sendMap);
    } catch(e) {
      print(e);
    }
    return value;
  }
要在Flutter调用Android原生方法,可以使用Flutter插件Flutter插件是一个将Flutter应用程序与原生平台通信的桥梁。下面是一些步骤来创建一个Flutter插件并在其中调用Android原生方法: 1. 使用Flutter插件模板创建一个Flutter插件: ``` flutter create --template=plugin <plugin-name> ``` 2. 在Flutter插件项目的`android`目录下,打开`build.gradle`文件,并添加以下代码: ``` dependencies { implementation 'io.flutter:flutter_embedding_v2.7.0' // 其他依赖项 } ``` 3. 在Flutter插件项目的`android/src/main`目录下,创建一个`java`包,并在其中创建一个类,该类将包含您要调用的Android原生方法。例如,您可以创建一个名为`MyPlugin`的类,并在其中添加以下代码: ``` package com.example.my_plugin; import android.content.Context; import android.widget.Toast; import io.flutter.embedding.engine.plugins.FlutterPlugin; public class MyPlugin implements FlutterPlugin { private Context context; @Override public void onAttachedToEngine(FlutterPluginBinding flutterPluginBinding) { context = flutterPluginBinding.getApplicationContext(); } @Override public void onDetachedFromEngine(FlutterPluginBinding flutterPluginBinding) { context = null; } public void showToast(String message) { Toast.makeText(context, message, Toast.LENGTH_SHORT).show(); } } ``` 4. 在Flutter插件项目的`lib`目录下,创建一个文件夹,并在其中创建一个`dart`文件,该文件将包含您要在Flutter调用方法。例如,您可以创建一个名为`my_plugin.dart`的文件,并在其中添加以下代码: ``` import 'package:flutter/services.dart'; class MyPlugin { static const MethodChannel _channel = const MethodChannel('my_plugin'); static Future<void> showToast(String message) async { try { await _channel.invokeMethod('showToast', {'message': message}); } on PlatformException catch (e) { print(e.message); } } } ``` 5. 在Flutter插件项目的`android/src/main`目录下,创建一个`res`目录,并在其中创建一个`values`目录。在`values`目录中,创建一个`strings.xml`文件,并添加以下代码: ``` <?xml version="1.0" encoding="utf-8"?> <resources> <string name="app_name">My Plugin</string> </resources> ``` 6. 在Flutter插件项目的`android/src/main`目录下,打开`AndroidManifest.xml`文件,并添加以下代码: ``` <application android:name="io.flutter.app.FlutterApplication" android:label="@string/app_name" android:icon="@mipmap/ic_launcher"> <activity android:name="io.flutter.embedding.android.FlutterActivity" android:exported="true" android:theme="@style/Theme.AppCompat.Light.NoActionBar"> <intent-filter> <action android:name="android.intent.action.MAIN"/> <category android:name="android.intent.category.LAUNCHER"/> </intent-filter> </activity> </application> ``` 7. 在Flutter插件项目的`android/src/main`目录下,打开`MyPlugin.java`文件,并添加以下代码: ``` package com.example.my_plugin; import android.content.Context; import android.widget.Toast; import io.flutter.embedding.engine.plugins.FlutterPlugin; import io.flutter.plugin.common.MethodCall; import io.flutter.plugin.common.MethodChannel; import io.flutter.plugin.common.PluginRegistry.Registrar; public class MyPlugin implements FlutterPlugin { private Context context; private MethodChannel channel; public static void registerWith(Registrar registrar) { final MethodChannel channel = new MethodChannel(registrar.messenger(), "my_plugin"); channel.setMethodCallHandler(new MyPlugin(registrar.context(), channel)); } private MyPlugin(Context context, MethodChannel channel) { this.context = context; this.channel = channel; } @Override public void onAttachedToEngine(FlutterPluginBinding flutterPluginBinding) { context = flutterPluginBinding.getApplicationContext(); channel = new MethodChannel(flutterPluginBinding.getBinaryMessenger(), "my_plugin"); channel.setMethodCallHandler(new MyPlugin(context, channel)); } @Override public void onDetachedFromEngine(FlutterPluginBinding flutterPluginBinding) { context = null; channel.setMethodCallHandler(null); channel = null; } public void showToast(String message) { Toast.makeText(context, message, Toast.LENGTH_SHORT).show(); } private void onMethodCall(MethodCall call, MethodChannel.Result result) { if (call.method.equals("showToast")) { String message = call.argument("message"); showToast(message); result.success(null); } else { result.notImplemented(); } } } ``` 8. 在Flutter应用程序中,导入您的Flutter插件,并使用以下代码调用Android原生方法: ``` import 'package:flutter/material.dart'; import 'package:my_plugin/my_plugin.dart'; void main() { runApp(MyApp()); } class MyApp extends StatelessWidget { @override Widget build(BuildContext context) { return MaterialApp( home: Scaffold( body: Center( child: ElevatedButton( onPressed: () { MyPlugin.showToast('Hello World!'); }, child: Text('Show Toast'), ), ), ), ); } } ``` 这样,您就可以在Flutter应用程序中调用Android原生方法了!
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