android添加flutter

进几年来flutter越来越火了，不学点感觉都要被时代给抛弃了。此文章只是记录一下学习。

在AS中新建flutter module

在settings.gradle中添加一下

setBinding(new Binding([gradle: this]))
evaluate(new File( settingsDir.parentFile, 'my_module/.android/include_flutter.groovy' ))

my_module是所键module的名字，直接替换就可以了

在activity中创建FrameLayout

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">
    <FrameLayout
        android:id="@+id/fragment_container"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

</LinearLayout>

在activity中创建flutter的Fragment,并在生命周期中回调flutter的生命周期方法

 override fun onPostResume() {
        super.onPostResume()
        flutterFragment!!.onPostResume()
    }

    override fun onNewIntent(intent: Intent?) {
        super.onNewIntent(intent)
        intent?.let {
            flutterFragment!!.onNewIntent(intent)
        }
    }

    override fun onBackPressed() {
        super.onBackPressed()
        flutterFragment!!.onBackPressed()
    }

    override fun onRequestPermissionsResult(
        requestCode: Int,
        permissions: Array<out String>,
        grantResults: IntArray
    ) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults)
        flutterFragment!!.onRequestPermissionsResult(requestCode, permissions, grantResults)
    }

    override fun onUserLeaveHint() {
        super.onUserLeaveHint()
        flutterFragment!!.onUserLeaveHint()
    }

    override fun onTrimMemory(level: Int) {
        super.onTrimMemory(level)
        flutterFragment!!.onTrimMemory(level)
    }

替换fragment

 override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_add_flutter_view)

        val fragmentLayout = findViewById<FrameLayout>(R.id.fragment_container)
        val fragmentManager: FragmentManager = supportFragmentManager
        flutterFragment =
            fragmentManager.findFragmentByTag(TAG_FLUTTER_FRAGMENT) as FlutterFragment?

        if (flutterFragment == null) {
            //添加指定的view
            var newFlutterFragment = FlutterFragment.withNewEngine()
                .dartEntrypoint("mySpecialEntrypoint")//需要在main方法外再添加新的入口
                .renderMode(RenderMode.texture)
                .build<FlutterFragment>()

            flutterFragment = newFlutterFragment
            fragmentManager.beginTransaction()
                .add(R.id.fragment_container, newFlutterFragment, TAG_FLUTTER_FRAGMENT)
                .commitAllowingStateLoss()
        }
    }

更改flutter入口方法，默认情况下main方法，一下是自定义的方法，需要你在main.dart中添加该方法。
FlutterFragment.withNewEngine().dartEntrypoint("mySpecialEntrypoint")
main.dart中默认是执行main方法，使用dartEntrypoint配置就会执行mySpecialEntrypoint这个方法，这样就可以自定义我们要加载的那个view.

void main() => runApp(MyApp());

void mySpecialEntrypoint() {
  runApp(
    MaterialApp(
      home: AddOriginalFragment(),
    ),
  );
}

flutter调用原生方法

fragmentLayout.viewTreeObserver.addOnGlobalLayoutListener(object :
                ViewTreeObserver.OnGlobalLayoutListener {
                override fun onGlobalLayout() {
                    Log.e("onResume", "======")
                    fragmentLayout.viewTreeObserver.removeOnGlobalLayoutListener(this)
                    flutterFragment!!.flutterEngine?.let { registerFlutter(it) }
                    if (flutterFragment!!.flutterEngine == null) {
                        Log.e("onResume", "flutterFragment is null")
                    }
                }

            })

 private fun registerFlutter(flutterEngine: FlutterEngine) {

        GeneratedPluginRegistrant.registerWith(flutterEngine)
        val methodChannel: MethodChannel =
            MethodChannel(flutterEngine.dartExecutor.binaryMessenger, FLUTTER_USED_NAME)
        methodChannel.setMethodCallHandler(object : MethodChannel.MethodCallHandler {
            override fun onMethodCall(call: MethodCall, result: MethodChannel.Result) {
                //TODO("Not yet implemented")
                Toast.makeText(this@AddFlutterViewActivity, "flutter 调用的", Toast.LENGTH_SHORT)
                    .show()
                result.success("调用成功")
            }

        })
    }

在页面加载完成后注册flutter通信通道，FLUTTER_USED_NAME是与flutter通道的句柄。在flutter中要用到
static const platormChannl = const MethodChannel("com.AddFlutterViewActivity.flutter_used_name");

void originalFunction() async{
    try{
     String result = (await platormChannl.invokeListMethod("flutterJumpFunction")) as String;
    } on Exception catch(e){
      print(e.toString());
    }

  }

调用原生方法要使用异步方法，flutterJumpFunction可以在原生这边call: MethodCall获取到。
这样就能走通的flutter调原生这一流程