Flutter国际化插件nls的使用

在Flutter开发中，国际化是一个非常重要的功能。本文将介绍如何使用nls插件来实现Flutter应用的国际化功能。

使用步骤

1. 添加依赖

首先，在pubspec.yaml文件中添加nls插件的依赖：

dependencies:
  nls: ^版本号

然后运行以下命令以获取依赖：

flutter pub get

2. 初始化插件

在main.dart文件中初始化nls插件并设置事件监听器。

import 'dart:async';

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:nls/nls.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatefulWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  State<MyApp> createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  String _platformVersion = 'Unknown';
  String qrCode = "";
  final _nlsPlugin = Nls();

  static const EventChannel _eventChannel = EventChannel('nlsresult');
  StreamSubscription? _streamSubscription;

  @override
  void initState() {
    super.initState();
    initPlatformState();
    // 监听来自原生端的消息
    _streamSubscription =
        _eventChannel.receiveBroadcastStream().listen((value) {
      try {
        print(value);
        setState(() {
          qrCode = value;
        });
      } catch (e, s) {
        print("e:" + e.toString());
        print(s);
      }
    });
  }

  // 获取平台版本信息
  Future<void> initPlatformState() async {
    String platformVersion;
    try {
      platformVersion =
          await _nlsPlugin.getPlatformVersion() ?? 'Unknown platform version';
    } on PlatformException {
      platformVersion = 'Failed to get platform version.';
    }

    if (!mounted) return;

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

  @override
  void dispose() {
    super.dispose();
    _streamSubscription?.cancel(); // 取消订阅以释放资源
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('NLS SCAN'),
        ),
        body: Column(
          mainAxisAlignment: MainAxisAlignment.start,
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: [
            Padding(
              padding: const EdgeInsets.all(10),
              child: Text(qrCode), // 显示扫描结果
            ),
            Padding(
              padding: const EdgeInsets.all(10),
              child: ElevatedButton(
                  onPressed: () {
                    _nlsPlugin.scan(); // 触发扫描操作
                  },
                  child: const Text("Scan")),
            )
          ],
        ),
      ),
    );
  }
}

3. 原生端集成

Android 端

在AndroidManifest.xml中添加必要的权限和配置：

<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera" />

<application>
  <activity android:name=".MainActivity">
    <intent-filter>
      <action android:name="android.intent.action.MAIN" />
      <category android:name="android.intent.category.LAUNCHER" />
    </intent-filter>
  </activity>
</application>

在MainActivity.java中注册广播通道：

import io.flutter.embedding.android.FlutterActivity;
import io.flutter.plugin.common.EventChannel;
import io.flutter.plugin.common.MethodChannel;

public class MainActivity extends FlutterActivity {
  private static final String CHANNEL = "nlsresult";

  @Override
  public void configureFlutterEngine(@NonNull FlutterEngine flutterEngine) {
    super.configureFlutterEngine(flutterEngine);

    new EventChannel(flutterEngine.getDartExecutor().getBinaryMessenger(), CHANNEL)
        .setStreamHandler(new EventChannel.StreamHandler() {
          @Override
          public void onListen(Object arguments, EventChannel.EventSink events) {
            // 收到消息时触发回调
            events.success("扫描成功");
          }

          @Override
          public void onCancel(Object arguments) {
            // 取消监听时触发
          }
        });
  }
}

iOS 端

在AppDelegate.swift中注册广播通道：

import UIKit
import Flutter

[@UIApplicationMain](/user/UIApplicationMain)
[@objc](/user/objc) class AppDelegate: FlutterAppDelegate {
  override func application(
    _ application: UIApplication,
    didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
  ) -> Bool {
    let controller : FlutterViewController = window?.rootViewController as! FlutterViewController
    let channel = FlutterEventChannel(name: "nlsresult", binaryMessenger: controller.binaryMessenger)
    
    channel.setStreamHandler({
      (arguments: Any?, eventSink: FlutterEventSink) -> FlutterError? in
      // 收到消息时触发回调
      eventSink("扫描成功")
      return nil
    })

    GeneratedPluginRegistrant.register(with: self)
    return super.application(application, didFinishLaunchingWithOptions: launchOptions)
  }
}