android - 添加到应用程序中不存在请求的 flutter 引擎

Question

我已经使用缓存的 flutter 引擎 flutter 到现有的 native 应用程序(添加到应用程序)中。

override fun onCreate(savedInstanceState: Bundle?) {
        Log.d(TAG, "onCreate")
        
        
        super.onCreate(savedInstanceState)

        setContentView(R.layout.activity_main)
        context = this.application.applicationContext
        if (!FlutterEngineCache.getInstance().contains(
                FLUTTER_ENGINE
            )
        ) {
            mFlutterEngine = FlutterEngine(context)
            mFlutterEngine.dartExecutor
                .executeDartEntrypoint(DartExecutor.DartEntrypoint.createDefault())
            FlutterEngineCache.getInstance()
                .put(FLUTTER_ENGINE, mFlutterEngine)
        }
        //Create Flutter Fragment
        mFragmentManager = supportFragmentManager
        mFlutterFragment = mFragmentManager.findFragmentByTag(FLUTTER_FRAGMENT) as FlutterFragment?
        if (mFlutterFragment == null) {
            mFlutterFragment =
                FlutterFragment.withCachedEngine(FLUTTER_ENGINE).transparencyMode(FlutterView.TransparencyMode.opaque).build()
            mFragmentManager
                .beginTransaction()
                .add(R.id.fragment_container, mFlutterFragment as Fragment, FLUTTER_FRAGMENT)
                .commit()
        } else {
            mFragmentManager
                .beginTransaction()
                .show(mFragmentManager.findFragmentByTag(FLUTTER_FRAGMENT)!!)
                .commit()
        }
}

我在生产应用程序中遇到以下崩溃

  Caused by: java.lang.IllegalStateException: The requested cached FlutterEngine did not exist in the FlutterEngineCache: 'FLUTTER_ENGINE'
        at io.flutter.embedding.android.FlutterActivityAndFragmentDelegate.setupFlutterEngine(FlutterActivityAndFragmentDelegate.java:211)
        at io.flutter.embedding.android.FlutterActivityAndFragmentDelegate.onAttach(FlutterActivityAndFragmentDelegate.java:157)
        at io.flutter.embedding.android.FlutterFragment.onAttach(FlutterFragment.java:597)
        at androidx.fragment.app.Fragment.performAttach(Fragment.java:2574)
        at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:828)
        at androidx.fragment.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManagerImpl.java:1238)
        at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:1303)
        at androidx.fragment.app.FragmentManagerImpl.dispatchStateChange(FragmentManagerImpl.java:2659)
        at androidx.fragment.app.FragmentManagerImpl.dispatchCreate(FragmentManagerImpl.java:2607)
        at androidx.fragment.app.FragmentController.dispatchCreate(FragmentController.java:235)
        at androidx.fragment.app.FragmentActivity.onCreate(FragmentActivity.java:316)
        at androidx.appcompat.app.AppCompatActivity.onCreate(AppCompatActivity.java:106)
        at com.flutter.android.MainActivity.onCreate(MainActivity.kt:33)
 

Answer 1

How to reproduce

打开开发者设置，将“后台进程”设置为“否”
后台进程”并设置为不保留 Activity 。

打开应用程序新闻和主页

再次打开应用程序..它会崩溃并出现异常。
原因:java.lang.IllegalStateException:请求的缓存 FlutterEngine 在 FlutterEngineCache 中不存在:'FLUTTER_ENGINE'

Solution

在 super.oncreate() 之前初始化 flutter 引擎

override fun onCreate(savedInstanceState: Bundle?) {
        Log.d(TAG, "onCreate")
         context = this.application.applicationContext
        if (!FlutterEngineCache.getInstance().contains(
                FLUTTER_ENGINE
            )
        ) {
            mFlutterEngine = FlutterEngine(context)
            mFlutterEngine.dartExecutor
                .executeDartEntrypoint(DartExecutor.DartEntrypoint.createDefault())
            FlutterEngineCache.getInstance()
                .put(FLUTTER_ENGINE, mFlutterEngine)
        }
       
        
        super.onCreate(savedInstanceState)

        setContentView(R.layout.activity_main)
        //Create Flutter Fragment
        mFragmentManager = supportFragmentManager
        mFlutterFragment = mFragmentManager.findFragmentByTag(FLUTTER_FRAGMENT) as FlutterFragment?
        if (mFlutterFragment == null) {
            mFlutterFragment =
                FlutterFragment.withCachedEngine(FLUTTER_ENGINE).transparencyMode(FlutterView.TransparencyMode.opaque).build()
            mFragmentManager
                .beginTransaction()
                .add(R.id.fragment_container, mFlutterFragment as Fragment, FLUTTER_FRAGMENT)
                .commit()
        } else {
            mFragmentManager
                .beginTransaction()
                .show(mFragmentManager.findFragmentByTag(FLUTTER_FRAGMENT)!!)
                .commit()
        }