[shared_preferences] Handling multiple files on Android

packages/shared_preferences/shared_preferences/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.6.0
+
+* Possibility to specify the file under which the preferences are stored on Android.
+
 ## 0.5.4+7
 
 * Restructure the project for Web support.

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

@@ -29,40 +29,62 @@
 @SuppressWarnings("unchecked")
 class MethodCallHandlerImpl implements MethodChannel.MethodCallHandler {
 
-  private static final String SHARED_PREFERENCES_NAME = "FlutterSharedPreferences";
+  private static final String SHARED_PREFERENCES_DEFAULT_NAME = "FlutterSharedPreferences";
+  private static final String CHANNEL_NAME = "plugins.flutter.io/shared_preferences";
+  private static final String PREFIX = "flutter.";
 
-  // Fun fact: The following is a base64 encoding of the string "This is the prefix for a list."
+  // 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 Context context;
+  private final HashMap<String, SharedPreferences> instances;
 
   /**
-   * Constructs a {@link MethodCallHandlerImpl} instance. Creates a {@link
-   * android.content.SharedPreferences} based on the {@code context}.
+   * Constructs a {@link MethodCallHandlerImpl} instance, and sets the {@link Context}. This should
+   * be used as a singleton. Use {@link #getPreferences} to get an instance of {@link
+   * SharedPreferences} associated to a specific file.
    */
   MethodCallHandlerImpl(Context context) {
-    preferences = context.getSharedPreferences(SHARED_PREFERENCES_NAME, Context.MODE_PRIVATE);
+    this.context = context;
+    this.instances = new HashMap<>();
+  }
+
+  /**
+   * @param filename The file to store the preferences.
+   * @return An instance of {@link SharedPreferences}.
+   */
+  private SharedPreferences getPreferences(String filename) {
+    if (filename == null) filename = SHARED_PREFERENCES_DEFAULT_NAME;
+    SharedPreferences instance = instances.get(filename);
+    if (instance == null) {
+      instance = context.getSharedPreferences(filename, Context.MODE_PRIVATE);
+      instances.put(filename, instance);
+    }
+    return instance;
   }
 
   @Override
   public void onMethodCall(MethodCall call, MethodChannel.Result result) {
-    String key = call.argument("key");
+    final String key = call.argument("key");
+    final String filename = call.argument("filename");
+    final SharedPreferences preferences = getPreferences(filename);
     try {
       switch (call.method) {
         case "setBool":
           commitAsync(preferences.edit().putBoolean(key, (boolean) call.argument("value")), result);
           break;
         case "setDouble":
-          double doubleValue = ((Number) call.argument("value")).doubleValue();
-          String doubleValueStr = Double.toString(doubleValue);
+          final double doubleValue = ((Number) call.argument("value")).doubleValue();
+          final String doubleValueStr = Double.toString(doubleValue);
           commitAsync(preferences.edit().putString(key, DOUBLE_PREFIX + doubleValueStr), result);
           break;
         case "setInt":
-          Number number = call.argument("value");
+          final Number number = call.argument("value");
           if (number instanceof BigInteger) {
-            BigInteger integerValue = (BigInteger) number;
+            final BigInteger integerValue = (BigInteger) number;
             commitAsync(
                 preferences
                     .edit()
@@ -74,7 +96,7 @@ public void onMethodCall(MethodCall call, MethodChannel.Result result) {
           }
           break;
         case "setString":
-          String value = (String) call.argument("value");
+          final String value = (String) call.argument("value");
           if (value.startsWith(LIST_IDENTIFIER) || value.startsWith(BIG_INTEGER_PREFIX)) {
             result.error(
                 "StorageError",
@@ -85,7 +107,7 @@ public void onMethodCall(MethodCall call, MethodChannel.Result result) {
           commitAsync(preferences.edit().putString(key, value), result);
           break;
         case "setStringList":
-          List<String> list = call.argument("value");
+          final List<String> list = call.argument("value");
           commitAsync(
               preferences.edit().putString(key, LIST_IDENTIFIER + encodeList(list)), result);
           break;
@@ -94,14 +116,14 @@ public void onMethodCall(MethodCall call, MethodChannel.Result result) {
           result.success(true);
           break;
         case "getAll":
-          result.success(getAllPrefs());
+          result.success(getAllPrefs(filename));
           return;
         case "remove":
           commitAsync(preferences.edit().remove(key), result);
           break;
         case "clear":
-          Set<String> keySet = getAllPrefs().keySet();
-          SharedPreferences.Editor clearEditor = preferences.edit();
+          final Set<String> keySet = getAllPrefs(filename).keySet();
+          final SharedPreferences.Editor clearEditor = preferences.edit();
           for (String keyToDelete : keySet) {
             clearEditor.remove(keyToDelete);
           }
@@ -161,36 +183,39 @@ private String encodeList(List<String> list) throws IOException {
   }
 
   // Filter preferences to only those set by the flutter app.
-  private Map<String, Object> getAllPrefs() throws IOException {
-    Map<String, ?> allPrefs = preferences.getAll();
-    Map<String, Object> filteredPrefs = new HashMap<>();
+  private Map<String, Object> getAllPrefs(String filename) throws IOException {
+    final SharedPreferences preferences = getPreferences(filename);
+    final Map<String, ?> allPrefs = preferences.getAll();
+    final Map<String, Object> filteredPrefs = new HashMap<>();
     for (String key : allPrefs.keySet()) {
-      if (key.startsWith("flutter.")) {
+      if (key.startsWith(PREFIX)) {
         Object value = allPrefs.get(key);
         if (value instanceof String) {
-          String stringValue = (String) value;
+          final String stringValue = (String) value;
           if (stringValue.startsWith(LIST_IDENTIFIER)) {
             value = decodeList(stringValue.substring(LIST_IDENTIFIER.length()));
           } else if (stringValue.startsWith(BIG_INTEGER_PREFIX)) {
-            String encoded = stringValue.substring(BIG_INTEGER_PREFIX.length());
+            final String encoded = stringValue.substring(BIG_INTEGER_PREFIX.length());
             value = new BigInteger(encoded, Character.MAX_RADIX);
           } else if (stringValue.startsWith(DOUBLE_PREFIX)) {
-            String doubleStr = stringValue.substring(DOUBLE_PREFIX.length());
+            final String doubleStr = stringValue.substring(DOUBLE_PREFIX.length());
             value = Double.valueOf(doubleStr);
           }
         } else if (value instanceof Set) {
           // This only happens for previous usage of setStringSet. The app expects a list.
-          List<String> listValue = new ArrayList<>((Set) value);
+          final List<String> listValue = new ArrayList<>((Set) value);
           // Let's migrate the value too while we are at it.
-          boolean success =
+          final boolean success =
               preferences
                   .edit()
                   .remove(key)
                   .putString(key, LIST_IDENTIFIER + encodeList(listValue))
                   .commit();
           if (!success) {
-            // If we are unable to migrate the existing preferences, it means we potentially lost them.
-            // In this case, an error from getAllPrefs() is appropriate since it will alert the app during plugin initialization.
+            // If we are unable to migrate the existing preferences, it means we potentially
+            // lost them.
+            // In this case, an error from getAllPrefs() is appropriate since it will alert
+            // the app during plugin initialization.
             throw new IOException("Could not migrate set to list");
           }
           value = listValue;

packages/shared_preferences/shared_preferences/example/test_driver/shared_preferences_e2e.dart

@@ -23,69 +23,118 @@ void main() {
       'flutter.List': <String>['baz', 'quox'],
     };
 
-    SharedPreferences preferences;
+    const String filename1 = "SharedPreferencesTests1";
+    const String filename2 = "SharedPreferencesTests2";
+
+    SharedPreferences preferences1;
+    SharedPreferences preferences2;
 
     setUp(() async {
-      preferences = await SharedPreferences.getInstance();
+      preferences1 = await SharedPreferences.getInstance(filename: filename1);
+      preferences2 = await SharedPreferences.getInstance(filename: filename2);
     });
 
     tearDown(() {
-      preferences.clear();
+      preferences1.clear();
     });
 
     test('reading', () async {
-      expect(preferences.get('String'), isNull);
-      expect(preferences.get('bool'), isNull);
-      expect(preferences.get('int'), isNull);
-      expect(preferences.get('double'), isNull);
-      expect(preferences.get('List'), isNull);
-      expect(preferences.getString('String'), isNull);
-      expect(preferences.getBool('bool'), isNull);
-      expect(preferences.getInt('int'), isNull);
-      expect(preferences.getDouble('double'), isNull);
-      expect(preferences.getStringList('List'), isNull);
+      expect(preferences1.get('String'), isNull);
+      expect(preferences1.get('bool'), isNull);
+      expect(preferences1.get('int'), isNull);
+      expect(preferences1.get('double'), isNull);
+      expect(preferences1.get('List'), isNull);
+      expect(preferences1.getString('String'), isNull);
+      expect(preferences1.getBool('bool'), isNull);
+      expect(preferences1.getInt('int'), isNull);
+      expect(preferences1.getDouble('double'), isNull);
+      expect(preferences1.getStringList('List'), isNull);
+
+      expect(preferences2.get('String'), isNull);
+      expect(preferences2.get('bool'), isNull);
+      expect(preferences2.get('int'), isNull);
+      expect(preferences2.get('double'), isNull);
+      expect(preferences2.get('List'), isNull);
+      expect(preferences2.getString('String'), isNull);
+      expect(preferences2.getBool('bool'), isNull);
+      expect(preferences2.getInt('int'), isNull);
+      expect(preferences2.getDouble('double'), isNull);
+      expect(preferences2.getStringList('List'), isNull);
     });
 
     test('writing', () async {
       await Future.wait(<Future<bool>>[
-        preferences.setString('String', kTestValues2['flutter.String']),
-        preferences.setBool('bool', kTestValues2['flutter.bool']),
-        preferences.setInt('int', kTestValues2['flutter.int']),
-        preferences.setDouble('double', kTestValues2['flutter.double']),
-        preferences.setStringList('List', kTestValues2['flutter.List'])
+        preferences1.setString('String', kTestValues2['flutter.String']),
+        preferences1.setBool('bool', kTestValues2['flutter.bool']),
+        preferences1.setInt('int', kTestValues2['flutter.int']),
+        preferences1.setDouble('double', kTestValues2['flutter.double']),
+        preferences1.setStringList('List', kTestValues2['flutter.List']),
+        preferences2.setString('String', kTestValues2['flutter.String']),
+        preferences2.setBool('bool', kTestValues2['flutter.bool']),
+        preferences2.setInt('int', kTestValues2['flutter.int']),
+        preferences2.setDouble('double', kTestValues2['flutter.double']),
+        preferences2.setStringList('List', kTestValues2['flutter.List'])
       ]);
-      expect(preferences.getString('String'), kTestValues2['flutter.String']);
-      expect(preferences.getBool('bool'), kTestValues2['flutter.bool']);
-      expect(preferences.getInt('int'), kTestValues2['flutter.int']);
-      expect(preferences.getDouble('double'), kTestValues2['flutter.double']);
-      expect(preferences.getStringList('List'), kTestValues2['flutter.List']);
+      expect(preferences1.getString('String'), kTestValues2['flutter.String']);
+      expect(preferences1.getBool('bool'), kTestValues2['flutter.bool']);
+      expect(preferences1.getInt('int'), kTestValues2['flutter.int']);
+      expect(preferences1.getDouble('double'), kTestValues2['flutter.double']);
+      expect(preferences1.getStringList('List'), kTestValues2['flutter.List']);
+
+      expect(preferences2.getString('String'), kTestValues2['flutter.String']);
+      expect(preferences2.getBool('bool'), kTestValues2['flutter.bool']);
+      expect(preferences2.getInt('int'), kTestValues2['flutter.int']);
+      expect(preferences2.getDouble('double'), kTestValues2['flutter.double']);
+      expect(preferences2.getStringList('List'), kTestValues2['flutter.List']);
     });
 
     test('removing', () async {
       const String key = 'testKey';
-      preferences
+      preferences1
         ..setString(key, kTestValues['flutter.String'])
         ..setBool(key, kTestValues['flutter.bool'])
         ..setInt(key, kTestValues['flutter.int'])
         ..setDouble(key, kTestValues['flutter.double'])
         ..setStringList(key, kTestValues['flutter.List']);
-      await preferences.remove(key);
-      expect(preferences.get('testKey'), isNull);
+      await preferences1.remove(key);
+      expect(preferences1.get('testKey'), isNull);
+
+      preferences2
+        ..setString(key, kTestValues['flutter.String'])
+        ..setBool(key, kTestValues['flutter.bool'])
+        ..setInt(key, kTestValues['flutter.int'])
+        ..setDouble(key, kTestValues['flutter.double'])
+        ..setStringList(key, kTestValues['flutter.List']);
+      await preferences2.remove(key);
+      expect(preferences2.get('testKey'), isNull);
     });
 
     test('clearing', () async {
-      preferences
+      preferences1
+        ..setString('String', kTestValues['flutter.String'])
+        ..setBool('bool', kTestValues['flutter.bool'])
+        ..setInt('int', kTestValues['flutter.int'])
+        ..setDouble('double', kTestValues['flutter.double'])
+        ..setStringList('List', kTestValues['flutter.List']);
+      await preferences1.clear();
+      expect(preferences1.getString('String'), null);
+      expect(preferences1.getBool('bool'), null);
+      expect(preferences1.getInt('int'), null);
+      expect(preferences1.getDouble('double'), null);
+      expect(preferences1.getStringList('List'), null);
+
+      preferences2
         ..setString('String', kTestValues['flutter.String'])
         ..setBool('bool', kTestValues['flutter.bool'])
         ..setInt('int', kTestValues['flutter.int'])
         ..setDouble('double', kTestValues['flutter.double'])
         ..setStringList('List', kTestValues['flutter.List']);
-      await preferences.clear();
-      expect(preferences.getString('String'), null);
-      expect(preferences.getBool('bool'), null);
-      expect(preferences.getInt('int'), null);
-      expect(preferences.getDouble('double'), null);
-      expect(preferences.getStringList('List'), null);
+      await preferences2.clear();
+      expect(preferences2.getString('String'), null);
+      expect(preferences2.getBool('bool'), null);
+      expect(preferences2.getInt('int'), null);
+      expect(preferences2.getDouble('double'), null);
+      expect(preferences2.getStringList('List'), null);
     });
   });
 }