[shared_preferences] Don't create additional Handler when method channel is called. (flutter#3639)

Author: hoc081098

packages/shared_preferences/shared_preferences/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 2.0.3
+
+* Android: don't create additional Handler when method channel is called.
+
 ## 2.0.2
 
 * Don't create additional thread pools when method channel is called.

packages/shared_preferences/shared_preferences/android/src/main/java/io/flutter/plugins/sharedpreferences/MethodCallHandlerImpl.java

@@ -44,6 +44,7 @@ class MethodCallHandlerImpl implements MethodChannel.MethodCallHandler {
   private final android.content.SharedPreferences preferences;
 
   private final ExecutorService executor;
+  private final Handler handler;
 
   /**
    * Constructs a {@link MethodCallHandlerImpl} instance. Creates a {@link
@@ -53,6 +54,7 @@ class MethodCallHandlerImpl implements MethodChannel.MethodCallHandler {
     preferences = context.getSharedPreferences(SHARED_PREFERENCES_NAME, Context.MODE_PRIVATE);
     executor =
         new ThreadPoolExecutor(0, 1, 30L, TimeUnit.SECONDS, new SynchronousQueue<Runnable>());
+    handler = new Handler(Looper.getMainLooper());
   }
 
   @Override
@@ -125,10 +127,13 @@ public void onMethodCall(MethodCall call, MethodChannel.Result result) {
     }
   }
 
+  public void teardown() {
+    handler.removeCallbacksAndMessages(null);
+    executor.shutdown();
+  }
+
   private void commitAsync(
       final SharedPreferences.Editor editor, final MethodChannel.Result result) {
-    final Handler handler = new Handler(Looper.getMainLooper());
-
     executor.execute(
         new Runnable() {
           @Override

packages/shared_preferences/shared_preferences/android/src/main/java/io/flutter/plugins/sharedpreferences/SharedPreferencesPlugin.java

@@ -13,6 +13,7 @@
 public class SharedPreferencesPlugin implements FlutterPlugin {
   private static final String CHANNEL_NAME = "plugins.flutter.io/shared_preferences";
   private MethodChannel channel;
+  private MethodCallHandlerImpl handler;
 
   @SuppressWarnings("deprecation")
   public static void registerWith(io.flutter.plugin.common.PluginRegistry.Registrar registrar) {
@@ -32,11 +33,13 @@ public void onDetachedFromEngine(FlutterPlugin.FlutterPluginBinding binding) {
 
   private void setupChannel(BinaryMessenger messenger, Context context) {
     channel = new MethodChannel(messenger, CHANNEL_NAME);
-    MethodCallHandlerImpl handler = new MethodCallHandlerImpl(context);
+    handler = new MethodCallHandlerImpl(context);
     channel.setMethodCallHandler(handler);
   }
 
   private void teardownChannel() {
+    handler.teardown();
+    handler = null;
     channel.setMethodCallHandler(null);
     channel = null;
   }

packages/shared_preferences/shared_preferences/pubspec.yaml

@@ -2,7 +2,7 @@ name: shared_preferences
 description: Flutter plugin for reading and writing simple key-value pairs.
   Wraps NSUserDefaults on iOS and SharedPreferences on Android.
 homepage: https://github.com/flutter/plugins/tree/master/packages/shared_preferences/shared_preferences
-version: 2.0.2
+version: 2.0.3
 
 flutter:
   plugin: