解决attempted to register plugin but it was already registered with this flutterengine

r囧r小猫 2023-01-13 09:12 157阅读 0赞

# 场景 #

Flutter版本更新后，运行出现以下问题，App闪退。

W/FlutterEngineCxnRegstry(10678): Attempted to register plugin (io.flutter.embedding.engine.plugins.shim.ShimPluginRegistry$ShimRegistrarAggregate@3777b26) but it was already registered with this FlutterEngine (io.flutter.embedding.engine.FlutterEngine@6c93367).
    E/AndroidRuntime(10678): FATAL EXCEPTION: main
    E/AndroidRuntime(10678): Process: com.example.firstflutterapp, PID: 10678
    E/AndroidRuntime(10678): java.lang.RuntimeException: Unable to start activity ComponentInfo{ com.example.firstflutterapp/com.example.firstflutterapp.MainActivity}: java.lang.NullPointerException: Attempt to invoke interface method 'void io.flutter.plugin.common.BinaryMessenger.setMessageHandler(java.lang.String, io.flutter.plugin.common.BinaryMessenger$BinaryMessageHandler)' on a null object reference
    E/AndroidRuntime(10678):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3898)
    E/AndroidRuntime(10678):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:4081)
    E/AndroidRuntime(10678):  at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:91)
    E/AndroidRuntime(10678):  at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:149)
    E/AndroidRuntime(10678):  at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:103)
    E/AndroidRuntime(10678):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2462)
    E/AndroidRuntime(10678):  at android.os.Handler.dispatchMessage(Handler.java:110)
    E/AndroidRuntime(10678):  at android.os.Looper.loop(Looper.java:219)
    E/AndroidRuntime(10678):  at android.app.ActivityThread.main(ActivityThread.java:8393)
    E/AndroidRuntime(10678):  at java.lang.reflect.Method.invoke(Native Method)
    E/AndroidRuntime(10678):  at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:513)
    E/AndroidRuntime(10678):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1055)
    E/AndroidRuntime(10678): Caused by: java.lang.NullPointerException: Attempt to invoke interface method 'void io.flutter.plugin.common.BinaryMessenger.setMessageHandler(java.lang.String, io.flutter.plugin.common.BinaryMessenger$BinaryMessageHandler)' on a null object reference
    E/AndroidRuntime(10678):  at io.flutter.plugin.common.MethodChannel.setMethodCallHandler(MethodChannel.java:119)
    E/AndroidRuntime(10678):  at com.jzoom.amaplocation.AmapLocationPlugin.registerWith(AmapLocationPlugin.java:54)
    E/AndroidRuntime(10678):  at io.flutter.plugins.GeneratedPluginRegistrant.registerWith(GeneratedPluginRegistrant.java:18)
    E/AndroidRuntime(10678):  at com.example.firstflutterapp.MainActivity.configureFlutterEngine(MainActivity.kt:31)
    E/AndroidRuntime(10678):  at io.flutter.embedding.android.FlutterActivityAndFragmentDelegate.onAttach(FlutterActivityAndFragmentDelegate.java:180)
    E/AndroidRuntime(10678):  at io.flutter.embedding.android.FlutterActivity.onCreate(FlutterActivity.java:409)
    E/AndroidRuntime(10678):  at android.app.Activity.performCreate(Activity.java:8121)
    E/AndroidRuntime(10678):  at android.app.Activity.performCreate(Activity.java:8109)
    E/AndroidRuntime(10678):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1320)
    E/AndroidRuntime(10678):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3871)
    E/AndroidRuntime(10678):  ... 11 more

# 解决方案 #

根据错误描述，是因为注册plugin时提示已经被注册过了了。  
涉及到插件，需要看官方文档。https://github.com/flutter/flutter/wiki/Upgrading-pre-1.12-Android-projects。  
以下是我的MainActivity.kt

class MainActivity: FlutterActivity() { 
      override fun configureFlutterEngine(@NonNull flutterEngine: FlutterEngine) { 
    	super.configureFlutterEngine(flutterEngine)
    	GeneratedPluginRegistrant.registerWith(flutterEngine)
      }
    }

这是官方代码

+    @Override
    +    public void configureFlutterEngine(@NonNull FlutterEngine flutterEngine) { 
    +        GeneratedPluginRegistrant.registerWith(flutterEngine);
    +        new MethodChannel(flutterEngine.getDartExecutor().getBinaryMessenger(), CHANNEL)
    +                .setMethodCallHandler(
    +                    (call, result) -> { 
    +                        // Your existing code
    +                }
    +        );
    +    }

发现多了个super方法，查看FlutterActivity源码发现，configureFlutterEngine方法已经调用过了GeneratedPluginRegistrant.registerWith(flutterEngine)，所以我们只需要删除super.configureFlutterEngine(flutterEngine)即可。

class MainActivity: FlutterActivity() { 
      override fun configureFlutterEngine(@NonNull flutterEngine: FlutterEngine) { 
    	//super.configureFlutterEngine(flutterEngine)
    	GeneratedPluginRegistrant.registerWith(flutterEngine)
      }
    }