5

我已经使用缓存的颤振引擎颤动到现有的本机应用程序（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)
4

2 回答 2

2

如何重现

  1. 打开开发人员设置，将“后台进程”设置为“无后台进程”并设置“不保留活动”。

  2. 打开应用程序新闻和主页

  3. 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'

解决方案

之前初始化颤振引擎super.oncreate()

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()
        }
于 2020-09-22T13:12:46.160 回答
0

我认为这里的问题是，当操作系统自动终止活动时，所有缓存引擎都会被终止，并且当您重新打开您的应用程序时，您必须控制您的颤动活动需要哪个 engineId。

例子：

  • 您的应用程序有 2 个活动：主页（缓存engineId0）=> 详细信息（缓存engineId1），并且您将引擎名称按升序排列（engineId1、engineId2、engineId3...）。当您在详细信息页面上时，您将应用程序置于后台并使用其他应用程序，然后有时操作系统会自动终止您的活动。
  • 当您返回您的应用程序时，它将打开详细信息页面（当然会再次进行 onCreate），但这里的问题是所有引擎都被杀死，然后您检查引擎不存在并重新创建engineId0（堆栈中的第一个引擎），然后您的代码使用此引擎，但 super.onCreate 处的 savedInstanceState 似乎仍然记得并engineId1在此详细信息页面上请求 => 导致问题。

解决方案：

  • 您必须找到一种方法来命名您的引擎，而不是按升序命名。
  • 像这样将 null 传递给 super.onCreatesuper.onCreate(null)然后它不会engineId1像我上面的示例那样请求。
于 2021-09-13T08:52:19.333 回答