原生提供功能，Dart module 通过 method channel 异步调用
1，安卓部分
手动注册
Flutter 官方的做法，就是自动注册插件，
很方便
手动注册，体现本文的不同
插件是 AudioRecorderPlugin
class MainActivity: FlutterActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
flutterEngine!!.plugins.add(AudioRecorderPlugin())
}
}
安卓和 Dart 的通讯
主要是消息回调
下文依次是，
- 开始录音
- 结束录音
- 正在录音
- 是否有录音权限
注意，这里的录音权限包含两个，麦克风的权限，和存储权限
@Override
public void onMethodCall(@NonNull MethodCall call, @NonNull Result result) {
switch (call.method) {
case "start":
Log.d(LOG_TAG, "Start");
Log.d(LOG_TAG, "11111____");
String path = call.argument("path");
mExtension = call.argument("extension");
startTime = Calendar.getInstance().getTime();
if (path != null) {
mFilePath = Environment.getExternalStorageDirectory().getAbsolutePath() + "/" + path;
} else {
Log.d(LOG_TAG, "11111____222");
String fileName = String.valueOf(startTime.getTime());
mFilePath = Environment.getExternalStorageDirectory().getAbsolutePath() + "/" + fileName + mExtension;
}
Log.d(LOG_TAG, mFilePath);
startRecording();
isRecording = true;
result.success(null);
break;
case "stop":
Log.d(LOG_TAG, "Stop");
stopRecording();
long duration = Calendar.getInstance().getTime().getTime() - startTime.getTime();
Log.d(LOG_TAG, "Duration : " + String.valueOf(duration));
isRecording = false;
HashMap<String, Object> recordingResult = new HashMap<>();
recordingResult.put("duration", duration);
recordingResult.put("path", mFilePath);
recordingResult.put("audioOutputFormat", mExtension);
result.success(recordingResult);
break;
case "isRecording":
Log.d(LOG_TAG, "Get isRecording");
result.success(isRecording);
break;
case "hasPermissions":
Log.d(LOG_TAG, "Get hasPermissions");
Context context = _flutterBinding.getApplicationContext();
PackageManager pm = context.getPackageManager();
int hasStoragePerm = pm.checkPermission(Manifest.permission.WRITE_EXTERNAL_STORAGE, context.getPackageName());
int hasRecordPerm = pm.checkPermission(Manifest.permission.RECORD_AUDIO, context.getPackageName());
boolean hasPermissions = hasStoragePerm == PackageManager.PERMISSION_GRANTED && hasRecordPerm == PackageManager.PERMISSION_GRANTED;
result.success(hasPermissions);
break;
default:
result.notImplemented();
break;
}
}
安卓录音
使用 wav 的封装格式，用 AudioRecord;
其他封装格式，用 MediaRecorder
上面两个播放器，有开始录音和结束录音功能；
暂停录音和恢复录音，则多次开始和结束，再把文件拼接在一起
Mac 上的安卓模拟器，不可录音
安卓真机，可以录音
2，Dart module 部分
建立 MethodChannel, 异步调用上面的原生功能
class AudioRecorder {
static const MethodChannel _channel = const MethodChannel('audio_recorder');
static LocalFileSystem fs = LocalFileSystem();
static Future start(String path, AudioOutputFormat audioOutputFormat) async {
String extension;
if (path != null) {
if (audioOutputFormat != null) {
if (_convertStringInAudioOutputFormat(p.extension(path)) !=
audioOutputFormat) {
extension = _convertAudioOutputFormatInString(audioOutputFormat);
path += extension;
} else {
extension = p.extension(path);
}
} else {
if (_isAudioOutputFormat(p.extension(path))) {
extension = p.extension(path);
} else {
extension = ".m4a"; // default value
path += extension;
}
}
File file = fs.file(path);
if (await file.exists()) {
throw new Exception("A file already exists at the path :" + path);
} else if (!await file.parent.exists()) {
throw new Exception("The specified parent directory does not exist");
}
} else {
extension = ".m4a"; // default value
}
return _channel
.invokeMethod('start', {"path": path, "extension": extension});
}
static Future<Recording?> stop() async {
// 把原生带出来的信息，放入字典中
Map<String, dynamic> response =
Map.from(await _channel.invokeMethod('stop'));
if (response != null) {
int duration = response['duration'];
String fmt = response['audioOutputFormat'];
AudioOutputFormat? outputFmt = _convertStringInAudioOutputFormat(fmt);
if (fmt != null && outputFmt != null) {
Recording recording = new Recording(
new Duration(milliseconds: duration),
response['path'],
outputFmt,
response['audioOutputFormat']);
return recording;
}
} else {
return null;
}
}
iOS 部分
手动注册插件
这里的插件名， 为 SwiftAudioRecorderPlugin
@UIApplicationMain
@objc class AppDelegate: FlutterAppDelegate {
override func application(
_ application: UIApplication,
didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
) -> Bool {
if let register = registrar(forPlugin: "SwiftAudioRecorderPlugin"){
SwiftAudioRecorderPlugin.register(with: register)
}
GeneratedPluginRegistrant.register(with: self)
return super.application(application, didFinishLaunchingWithOptions: launchOptions)
}
}
iOS 插件
逻辑与安卓插件类似，
因为 iOS 的 AVAudioRecorder 对 pause 和 resume 操作，支持友好，
所以增添了暂停和恢复录音功能
iOS 端的权限比安卓权限，少一个
仅需要录音麦克风权限
public class SwiftAudioRecorderPlugin: NSObject, FlutterPlugin {
var isRecording = false
var hasPermissions = false
var mExtension = ""
var mPath = ""
var startTime: Date!
var audioRecorder: AVAudioRecorder?
public static func register(with registrar: FlutterPluginRegistrar) {
let channel = FlutterMethodChannel(name: "audio_recorder", binaryMessenger: registrar.messenger())
let instance = SwiftAudioRecorderPlugin()
registrar.addMethodCallDelegate(instance, channel: channel)
}
public func handle(_ call: FlutterMethodCall, result: @escaping FlutterResult) {
switch call.method {
case "start":
print("start")
let dic = call.arguments as! [String : Any]
mExtension = dic["extension"] as? String ?? ""
mPath = dic["path"] as? String ?? ""
startTime = Date()
let documentsPath = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0]
if mPath == "" {
mPath = documentsPath + "/" + String(Int(startTime.timeIntervalSince1970)) + ".m4a"
}
else{
mPath = documentsPath + "/" + mPath
}
print("path: " + mPath)
let settings = [
AVFormatIDKey: getOutputFormatFromString(mExtension),
AVSampleRateKey: 12000,
AVNumberOfChannelsKey: 1,
AVEncoderAudioQualityKey: AVAudioQuality.high.rawValue
]
do {
try AVAudioSession.sharedInstance().setCategory(AVAudioSession.Category.playAndRecord, options: AVAudioSession.CategoryOptions.defaultToSpeaker)
try AVAudioSession.sharedInstance().setActive(true)
let recorder = try AVAudioRecorder(url: URL(string: mPath)!, settings: settings)
recorder.delegate = self
recorder.record()
audioRecorder = recorder
} catch {
print("fail")
result(FlutterError(code: "", message: "Failed to record", details: nil))
}
isRecording = true
result(nil)
case "pause":
audioRecorder?.pause()
result(nil)
case "resume":
audioRecorder?.record()
result(nil)
case "stop":
print("stop")
audioRecorder?.stop()
audioRecorder = nil
let duration = Int(Date().timeIntervalSince(startTime as Date) * 1000)
isRecording = false
var recordingResult = [String : Any]()
recordingResult["duration"] = duration
recordingResult["path"] = mPath
recordingResult["audioOutputFormat"] = mExtension
result(recordingResult)
case "isRecording":
print("isRecording")
result(isRecording)
case "hasPermissions":
print("hasPermissions")
switch AVAudioSession.sharedInstance().recordPermission{
case AVAudioSession.RecordPermission.granted:
print("granted")
hasPermissions = true
case AVAudioSession.RecordPermission.denied:
print("denied")
hasPermissions = false
case AVAudioSession.RecordPermission.undetermined:
print("undetermined")
AVAudioSession.sharedInstance().requestRecordPermission() { [unowned self] allowed in
DispatchQueue.main.async {
if allowed {
self.hasPermissions = true
} else {
self.hasPermissions = false
}
}
}
default:()
}
result(hasPermissions)
default:
result(FlutterMethodNotImplemented)
}
}
}
Dart 调用部分
通过判断平台，Platform.isIOS,
给 iOS 设备，增加完善的功能
@override
Widget build(BuildContext context) {
final VoidCallback tapFirst;
if (Platform.isAndroid && name == kEnd) {
tapFirst = _audioEnd;
} else {
tapFirst = _audioGoOn;
}
List<Widget> views = [ ElevatedButton( child: Text( name, style: Theme.of(context).textTheme.headline4, ), onPressed: tapFirst, ) ];
if (Platform.isIOS && name != kStarted) {
views.add(SizedBox(height: 80));
views.add(ElevatedButton(
child: Text(
kEnd,
style: Theme.of(context).textTheme.headline4,
),
onPressed: _audioEnd,
));
}
return Scaffold(
appBar: AppBar(
// Here we take the value from the MyHomePage object that was created by
// the App.build method, and use it to set our appbar title.
title: Text(widget.title),
),
body: Center(
// Center is a layout widget. It takes a single child and positions it
// in the middle of the parent.
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: views,
),
), // This trailing comma makes auto-formatting nicer for build methods.
);
}
