android - 如何将方法 channel 添加到 Flutter Fragment

Question

自从我将 Flutter SDK 升级到 1.12.13+hotfix.8 后， fragment 中较旧的 FlutterView 实现不再有效，因为 Facade (Flutter) 库现在已弃用。

Flutter.createView(activity!!, lifecycle, mRoute)

根据官方文档，我们可以添加如下所示的 FlutterFragment -

FlutterFragment flutterFragment = FlutterFragment.withNewEngine()
    .initialRoute("myInitialRoute/")
    .build();

但找不到如何在扩展 Flutter fragment 的自定义 Flutter fragment 中添加方法 channel 。

Answer 1

这就是我将 flutter 引擎与 flutter fragment 连接的方式，它运行得非常好。如果你使用缓存的引擎和 fragment ，即使你重新打开它，屏幕也会保持状态。如果您不想保存 fragment 状态，请避免缓存。

package com.test.app

import io.flutter.embedding.android.FlutterFragment
import io.flutter.embedding.engine.FlutterEngine
import io.flutter.embedding.engine.FlutterEngineCache
import io.flutter.embedding.engine.dart.DartExecutor
import io.flutter.plugin.common.MethodChannel

class SampleActivity: AppCompatActivity() {

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

        initFlutterEngine()
        attachFlutterFragment()
    }

    private fun initFlutterEngine(): FlutterEngine {
        var flutterEngine = FlutterEngineCache.getInstance().get(ENGINE_ID)

        if (null == flutterEngine) {
            flutterEngine = FlutterEngine(this)
            flutterEngine.navigationChannel.setInitialRoute("/")
            flutterEngine.dartExecutor.executeDartEntrypoint(
                DartExecutor.DartEntrypoint.createDefault()
            )
            FlutterEngineCache
                .getInstance()
                .put(ENGINE_ID, flutterEngine)
            setMethodChannels(flutterEngine)
        }
        return flutterEngine
    }

    private attachFlutterFragment() {
        var flutterFragment = supportFragmentManager.findFragmentByTag(FRAGMENT_TAG) as FlutterFragment?
        if (null == flutterFragment) {
            flutterFragment =
                FlutterFragment.withCachedEngine(ENGINE_ID)
                    .shouldAttachEngineToActivity(true)
                    .build() as FlutterFragment
        }

        supportFragmentManager
            .beginTransaction()
            .add(R.id.flutter_fragment_container,
                 flutterFragment,
                 FRAGMENT_TAG
            )
            .commit()
    }

    private fun setMethodChannels(flutterEngine: FlutterEngine) {
        MethodChannel(flutterEngine.dartExecutor, FLUTTER_CHANNEL).setMethodCallHandler { call, result ->
            when (call.method) {
                DUMMY_METHOD -> {
                    val params = HashMap<String, String>()

                    result.success(params)
                }
                else -> result.notImplemented()
            }
        }
    }
}