这个代码结构是如何生成的呢？
开发环境：AndroidStudio3.5
在旧版中试过，只会把module导进来，就是这个：
flutter create -t module flutter_module3
2、修改Android工程settings.gradle文件
include ':app'
rootProject.name='My Application'
//加入下面配置
setBinding(new Binding([gradle: this]))
evaluate(new File(
settingsDir.parentFile,
'flutter_module3/.android/include_flutter.groovy'
))
3、修改app下的build.gradle文件
dependencies {
implementation fileTree(dir: 'libs', include: ['*.jar'])
implementation"org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
implementation 'androidx.appcompat:appcompat:1.0.2'
implementation 'androidx.core:core-ktx:1.0.2'
implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
testImplementation 'junit:junit:4.12'
androidTestImplementation 'androidx.test.ext:junit:1.1.0'
androidTestImplementation 'androidx.test.espresso:espresso-core:3.1.1'
// 加入下面配置
implementation project(':flutter')
}
channel总共有三种类型：MethodChannel、EventChannel、BasicMessageChannel
BasicMessageChannel用法
Android可以给flutter发送消息并且接收flutter的返回值，flutter可以给Android发送消息，但是无法接收返回值（没有找到如何接受）
核心代码： Android端
final BasicMessageChannel messageChannel = new BasicMessageChannel<>(flutterView, CHANNEL, StringCodec.INSTANCE);
messageChannel.
setMessageHandler(new BasicMessageChannel.MessageHandler<String>() {
public void onMessage(String s, BasicMessageChannel.Reply<String> reply) {
//接收到flutter主动发送的消息了
tv2.setText(s);
//这是回传给flutter的，但是flutter无法接收
reply.reply("Android已经收到消息了");
}
});
tv.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View v) {
messageChannel.send("这是Android给你发送的消息");
messageChannel.send("这是Android给你发送的消息",new BasicMessageChannel.Reply(){
@Override
public void reply(Object o) {
tv3.setText(o.toString());
}
});
}
});
flutter端：
class HomePageBasicMessageChannel extends StatefulWidget
{
@override
State<StatefulWidget> createState() {
return HomePageBasicMessageChannelState();
}
}
class HomePageBasicMessageChannelState extends State<HomePageBasicMessageChannel>
{
static const BasicMessageChannel<String> platform = BasicMessageChannel<String>('samples.flutter.io/basic', StringCodec());
String result;
String result2;
Future<String> _handlePlatformIncrement(String message) async {
//这儿接收Android端发送的消息
setState(() {
result=message;
});
//这是回传给Android端的，Android可以接收
return "flutter收到消息了，这是返给你的信息";
}
@override
Widget build(BuildContext context) {
platform.setMessageHandler(_handlePlatformIncrement);
return Scaffold(
body: Center(
child: Column(
children: <Widget>[
Text("接收到Android端发过来的信息：${result}"),
InkWell(
child: Text("发送消息"),
onTap: (){
//这儿是主动给Android发送消息的代码
platform.send("flutter主动发送的消息");
},
),
Text("flutter主动发送消息后，Android给的返回值：${result2}")
],
),
),
);
}
}
EventChannel使用
感觉更像是一个观察者模式的运用，当flutter想要监听的事件发生变化后（比如网络变化、电量变化），Android会主动发送事件给flutter，比如说flutter想要实时获取电量的变化，如果使用EventChannel的话就不需要去轮询了
核心代码：
Android端：
new EventChannel(flutterView, "samples.flutter.io/charging").setStreamHandler(
new EventChannel.StreamHandler() {
// 接收电池广播的BroadcastReceiver。
private BroadcastReceiver chargingStateChangeReceiver;
@Override
// 这个onListen是Flutter端开始监听这个channel时的回调，第二个参数 EventSink是用来传数据的载体。
public void onListen(Object arguments, EventChannel.EventSink events) {
globaleEvents=events;
chargingStateChangeReceiver = createChargingStateChangeReceiver(events);
registerReceiver(
chargingStateChangeReceiver, new IntentFilter(Intent.ACTION_BATTERY_CHANGED));
}
@Override
public void onCancel(Object arguments) {
// 对面不再接收
unregisterReceiver(chargingStateChangeReceiver);
chargingStateChangeReceiver = null;
}
}
);
tv2.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View v) {
//手动模拟电量发生了变化
if(globaleEvents!=null)
{
globaleEvents.success("电量变化了啊："+ new Random().nextInt(20));
}
}
});
/**
* 这是监听系统电量发生变化的广播
* @param events
* @return
*/
private BroadcastReceiver createChargingStateChangeReceiver(final EventChannel.EventSink events) {
return new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
int status = intent.getIntExtra(BatteryManager.EXTRA_STATUS, -1);
if (status == BatteryManager.BATTERY_STATUS_UNKNOWN) {
events.error("UNAVAILABLE", "Charging status unavailable", null);
} else {
boolean isCharging = status == BatteryManager.BATTERY_STATUS_CHARGING ||
status == BatteryManager.BATTERY_STATUS_FULL;
// 把电池状态发给Flutter
events.success(isCharging ? "charging" : "discharging");
}
}
};
}
flutter 端：
class HomePageEventState extends State<HomePageEvent>
{
static const EventChannel eventChannel = const EventChannel('samples.flutter.io/charging');
String _chargingStatus;
@override
void initState() {
super.initState();
eventChannel.receiveBroadcastStream().listen(_onEvent, onError: _onError);
}
//这儿是接收Android端发送来的消息
void _onEvent(Object event) {
setState(() {
// _chargingStatus =
// "Battery status: ${event == 'charging' ? '' : 'dis'}charging.";
_chargingStatus=event.toString();
});
}
void _onError(Object error) {
setState(() {
_chargingStatus = 'Battery status: unknown.';
});
}
@override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: Text("${_chargingStatus}"),
),
);
}
}
MethodChannel
MethodChannel更像是用来互相调用对方的方法，Android调用flutter的方法时，可以传入参数，flutter调用Android的方法时，没有找到传参的地方，Android端和flutter端使用的方法都是相近的
核心代码： Android端
final MethodChannel channel=new MethodChannel(flutterView, CHANNEL);
channel.setMethodCallHandler(
new MethodChannel.MethodCallHandler() {
@Override
public void onMethodCall(MethodCall call, MethodChannel.Result result) {
// 在这个回调里处理从Flutter来的调用
if (call.method.equals("getBatteryLevel")) {
int batteryLevel = getBatteryLevel();
if (batteryLevel != -1) {
result.success(batteryLevel);
} else {
result.error("UNAVAILABLE", "Battery level not available.", null);
}
} else {
result.notImplemented();
}
}
});
tv.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View v) {
//这三个参数不要写错，无语，arguments应该可以携带参数
channel.invokeMethod("getName","abc",new MethodChannel.Result(){
@Override
public void success(Object o) {
Toast.makeText(MainActivity.this,o.toString(),Toast.LENGTH_LONG).show();
}
@Override
public void error(String s, String s1, Object o) {
}
@Override
public void notImplemented() {
}
});
}
});
private int getBatteryLevel() {
int batteryLevel = -1;
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
BatteryManager batteryManager = (BatteryManager) getSystemService(BATTERY_SERVICE);
batteryLevel = batteryManager.getIntProperty(BatteryManager.BATTERY_PROPERTY_CAPACITY);
} else {
Intent intent = new ContextWrapper(getApplicationContext()).
registerReceiver(null, new IntentFilter(Intent.ACTION_BATTERY_CHANGED));
batteryLevel = (intent.getIntExtra(BatteryManager.EXTRA_LEVEL, -1) * 100) /
intent.getIntExtra(BatteryManager.EXTRA_SCALE, -1);
}
return batteryLevel;
}
flutter端：
class _MyHomePageState extends State<HomePage>
{
MethodChannel platform = const MethodChannel('samples.flutter.io/battery');
String _batteryLevel = 'Unknown battery level.';
Future<Null> _getBatteryLevel() async {
String batteryLevel;
try {
final int result = await platform.invokeMethod('getBatteryLevel');
batteryLevel = 'Battery level at $result % .';
} on PlatformException catch (e) {
batteryLevel = "Failed to get battery level: '${e.message}'.";
}
setState(() {
_batteryLevel = batteryLevel;
});
}
Future<dynamic> platformCallHandler(MethodCall call) async {
//call.method是获取方法名，call.arguments是获取方法参数
switch (call.method) {
case "getName":
return "Hello from Flutter:${call.arguments}";
break;
}
}
@override
Widget build(BuildContext context) {
//为了使原生也可以调用到flutter中的方法
platform.setMethodCallHandler(platformCallHandler);
// TODO: implement build
return Scaffold(
body: Center(
child:Column(
children: <Widget>[
Text("电量:${_batteryLevel}"),
IconButton(
icon: Icon(Icons.ac_unit), onPressed: (){
_getBatteryLevel();
},
tooltip: "获取电量",
)
],
)
),
);
}
}
