[shared_preferences] replace AsyncTask by Executor and Guava Future

packages/shared_preferences/shared_preferences/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.5.13+3
+
+* Android: replace [AsyncTask](https://developer.android.com/reference/android/os/AsyncTask) (was deprecated in API level 30) by [Executor](https://developer.android.com/reference/java/util/concurrent/Executor)
+
 ## 0.5.13+2
 
 * Fix outdated links across a number of markdown files ([#3276](https://github.com/flutter/plugins/pull/3276))

packages/shared_preferences/shared_preferences/android/build.gradle

@@ -40,3 +40,7 @@ android {
         disable 'InvalidPackage'
     }
 }
+
+dependencies {
+    implementation 'com.google.guava:guava:28.1-android'
+}

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

@@ -6,8 +6,15 @@
 
 import android.content.Context;
 import android.content.SharedPreferences;
-import android.os.AsyncTask;
+import android.os.Handler;
+import android.os.Looper;
 import android.util.Base64;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import com.google.common.util.concurrent.FutureCallback;
+import com.google.common.util.concurrent.Futures;
+import com.google.common.util.concurrent.SettableFuture;
+import com.google.common.util.concurrent.ThreadFactoryBuilder;
 import io.flutter.plugin.common.MethodCall;
 import io.flutter.plugin.common.MethodChannel;
 import java.io.ByteArrayInputStream;
@@ -21,6 +28,9 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
+import java.util.concurrent.Executor;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
 
 /**
  * Implementation of the {@link MethodChannel.MethodCallHandler} for the plugin. It is also
@@ -30,24 +40,34 @@
 class MethodCallHandlerImpl implements MethodChannel.MethodCallHandler {
 
   private static final String SHARED_PREFERENCES_NAME = "FlutterSharedPreferences";
+  private static final String SHARED_PREFERENCES_ERROR_CODE = "shared-preferences-error";
 
   // Fun fact: The following is a base64 encoding of the string "This is the prefix for a list."
   private static final String LIST_IDENTIFIER = "VGhpcyBpcyB0aGUgcHJlZml4IGZvciBhIGxpc3Qu";
   private static final String BIG_INTEGER_PREFIX = "VGhpcyBpcyB0aGUgcHJlZml4IGZvciBCaWdJbnRlZ2Vy";
   private static final String DOUBLE_PREFIX = "VGhpcyBpcyB0aGUgcHJlZml4IGZvciBEb3VibGUu";
 
   private final android.content.SharedPreferences preferences;
+  private final ExecutorService executor;
+  private final Executor uiThreadExecutor;
 
   /**
    * Constructs a {@link MethodCallHandlerImpl} instance. Creates a {@link
    * android.content.SharedPreferences} based on the {@code context}.
    */
   MethodCallHandlerImpl(Context context) {
     preferences = context.getSharedPreferences(SHARED_PREFERENCES_NAME, Context.MODE_PRIVATE);
+    executor =
+        Executors.newSingleThreadExecutor(
+            new ThreadFactoryBuilder()
+                .setNameFormat("shared-preferences-background-%d")
+                .setPriority(Thread.NORM_PRIORITY)
+                .build());
+    uiThreadExecutor = new UiThreadExecutor();
   }
 
   @Override
-  public void onMethodCall(MethodCall call, MethodChannel.Result result) {
+  public void onMethodCall(MethodCall call, @NonNull MethodChannel.Result result) {
     String key = call.argument("key");
     try {
       switch (call.method) {
@@ -118,17 +138,42 @@ public void onMethodCall(MethodCall call, MethodChannel.Result result) {
 
   private void commitAsync(
       final SharedPreferences.Editor editor, final MethodChannel.Result result) {
-    new AsyncTask<Void, Void, Boolean>() {
-      @Override
-      protected Boolean doInBackground(Void... voids) {
-        return editor.commit();
-      }
+    if (executor.isShutdown()) {
+      return;
+    }
 
-      @Override
-      protected void onPostExecute(Boolean value) {
-        result.success(value);
-      }
-    }.execute();
+    final SettableFuture<Boolean> future = SettableFuture.create();
+
+    Futures.addCallback(
+        future,
+        new FutureCallback<Boolean>() {
+          @Override
+          public void onSuccess(@Nullable Boolean b) {
+            if (b != null) {
+              result.success(b);
+            } else {
+              result.error(SHARED_PREFERENCES_ERROR_CODE, "Null result", null);
+            }
+          }
+
+          @Override
+          public void onFailure(@NonNull Throwable t) {
+            result.error(SHARED_PREFERENCES_ERROR_CODE, t.getMessage(), null);
+          }
+        },
+        uiThreadExecutor);
+
+    executor.execute(
+        new Runnable() {
+          @Override
+          public void run() {
+            try {
+              future.set(editor.commit());
+            } catch (Throwable t) {
+              future.setException(t);
+            }
+          }
+        });
   }
 
   private List<String> decodeList(String encodedList) throws IOException {
@@ -200,4 +245,17 @@ private Map<String, Object> getAllPrefs() throws IOException {
     }
     return filteredPrefs;
   }
+
+  void teardown() {
+    executor.shutdown();
+  }
+
+  private static class UiThreadExecutor implements Executor {
+    private final Handler handler = new Handler(Looper.getMainLooper());
+
+    @Override
+    public void execute(Runnable command) {
+      handler.post(command);
+    }
+  }
 }

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 +33,12 @@ 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();
     channel.setMethodCallHandler(null);
     channel = null;
   }

packages/shared_preferences/shared_preferences/pubspec.yaml

@@ -5,7 +5,7 @@ homepage: https://github.com/flutter/plugins/tree/master/packages/shared_prefere
 # 0.5.y+z is compatible with 1.0.0, if you land a breaking change bump
 # the version to 2.0.0.
 # See more details: https://github.com/flutter/flutter/wiki/Package-migration-to-1.0.0
-version: 0.5.13+2
+version: 0.5.13+3
 
 flutter:
   plugin: