如何在Flutter应用中同时启用硬件键盘与软件键盘

在配备硬件条码扫描器的Flutter应用中，系统默认会在硬件键盘连接时隐藏软件键盘，要实现软硬共存，需要分平台处理并结合Flutter代码调整：

Android 端配置与原生调用 #

1. 修改AndroidManifest.xml
   在<activity>标签中添加软键盘模式配置，确保基础显示逻辑：

   <activity
       ...
       android:windowSoftInputMode="stateVisible|adjustResize">
   

2. 通过MethodChannel强制唤起软键盘
   由于硬件键盘连接时系统会自动隐藏软键盘，需通过原生代码强制显示：

   • 在Android项目的MainActivity中添加MethodChannel实现：

     import android.content.Context
     import android.view.inputmethod.InputMethodManager
     import io.flutter.embedding.android.FlutterActivity
     import io.flutter.embedding.engine.FlutterEngine
     import io.flutter.plugin.common.MethodChannel
     
     class MainActivity : FlutterActivity() {
         private val CHANNEL = "keyboard_utils"
     
         override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
             super.configureFlutterEngine(flutterEngine)
             MethodChannel(flutterEngine.dartExecutor.binaryMessenger, CHANNEL).setMethodCallHandler { call, result ->
                 when (call.method) {
                     "showSoftKeyboard" -> {
                         val imm = getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager
                         val view = currentFocus ?: window.decorView.rootView
                         imm.showSoftInput(view, InputMethodManager.SHOW_FORCED)
                         result.success(null)
                     }
                     else -> result.notImplemented()
                 }
             }
         }
     }
     

iOS 端原生调用 #

iOS系统默认不会在硬件键盘连接时自动显示软键盘，同样通过MethodChannel实现强制唤起：

• 在iOS项目的AppDelegate中添加MethodChannel实现：

  import UIKit
  import Flutter
  
  @UIApplicationMain
  @objc class AppDelegate: FlutterAppDelegate {
      private let CHANNEL = "keyboard_utils"
  
      override func application(
          _ application: UIApplication,
          didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
      ) -> Bool {
          let controller : FlutterViewController = window?.rootViewController as! FlutterViewController
          let channel = FlutterMethodChannel(name: CHANNEL, binaryMessenger: controller.binaryMessenger)
          channel.setMethodCallHandler { [weak self] call, result in
              guard let self = self else { return }
              switch call.method {
              case "showSoftKeyboard":
                  guard let view = UIApplication.shared.keyWindow?.rootViewController?.view else {
                      result.error("VIEW_NOT_FOUND", "No view found to attach keyboard", nil)
                      return
                  }
                  view.becomeFirstResponder()
                  // 强制唤起软键盘
                  if let inputVC = self.getTextInputViewController() {
                      inputVC.showKeyboard(true)
                  }
                  result.success(nil)
              default:
                  result.notImplemented()
              }
          }
          GeneratedPluginRegistrant.register(with: self)
          return super.application(application, didFinishLaunchingWithOptions: launchOptions)
      }
  
      private func getTextInputViewController() -> UIInputViewController? {
          for window in UIApplication.shared.windows {
              if let inputVC = window.rootViewController as? UIInputViewController {
                  return inputVC
              }
          }
          return nil
      }
  }
  

Flutter 端调用逻辑 #

在Flutter代码中，通过MethodChannel调用原生方法，在需要显示软键盘的时机（如TextField获取焦点后）触发：

import 'package:flutter/services.dart';

class KeyboardHelper {
  static const MethodChannel _channel = MethodChannel('keyboard_utils');

  /// 强制显示软件键盘
  static Future<void> forceShowSoftKeyboard() async {
    try {
      await _channel.invokeMethod('showSoftKeyboard');
    } on PlatformException catch (e) {
      print('唤起软键盘失败: ${e.message}');
    }
  }
}

// 使用示例
class MyTextField extends StatefulWidget {
  @override
  State<MyTextField> createState() => _MyTextFieldState();
}

class _MyTextFieldState extends State<MyTextField> {
  final FocusNode _focusNode = FocusNode();

  @override
  void initState() {
    super.initState();
    _focusNode.addListener(() {
      if (_focusNode.hasFocus) {
        // 获取焦点后强制唤起软键盘
        KeyboardHelper.forceShowSoftKeyboard();
      }
    });
  }

  @override
  void dispose() {
    _focusNode.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return TextField(
      focusNode: _focusNode,
      decoration: const InputDecoration(hintText: '输入内容'),
    );
  }
}

额外注意事项 #

• 确保你的TextField或输入组件已正确设置focusNode，这样在获取焦点时才能触发软键盘唤起逻辑。
• Android端部分设备可能需要开启“允许同时使用软硬键盘”的系统设置，但通过上述代码可绕过手动设置强制唤起。

内容的提问来源于stack exchange，提问作者SonOfGillas