Merge "DO NOT MERGE Create a key value settings observer for backup parameters" into pi-dev

core/java/android/util/KeyValueSettingObserver.java

@@ -0,0 +1,97 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.util;
+
+import android.content.ContentResolver;
+import android.database.ContentObserver;
+import android.net.Uri;
+import android.os.Handler;
+
+/**
+ * Abstract class for observing changes to a specified setting stored as a comma-separated key value
+ * list of parameters. Registers and unregisters a {@link ContentObserver} and handles updates when
+ * the setting changes.
+ *
+ * <p>Subclasses should pass in the relevant setting's {@link Uri} in the constructor and implement
+ * {@link #update(KeyValueListParser)} to receive updates when the value changes.
+ * Calls to {@link #update(KeyValueListParser)} only trigger after calling {@link
+ * #start()}.
+ *
+ * <p>To get the most up-to-date parameter values, first call {@link #start()} before accessing the
+ * values to start observing changes, and then call {@link #stop()} once finished.
+ *
+ * @hide
+ */
+public abstract class KeyValueSettingObserver {
+    private static final String TAG = "KeyValueSettingObserver";
+
+    private final KeyValueListParser mParser = new KeyValueListParser(',');
+
+    private final ContentObserver mObserver;
+    private final ContentResolver mResolver;
+    private final Uri mSettingUri;
+
+    public KeyValueSettingObserver(Handler handler, ContentResolver resolver,
+            Uri uri) {
+        mObserver = new SettingObserver(handler);
+        mResolver = resolver;
+        mSettingUri = uri;
+    }
+
+    /** Starts observing changes for the setting. Pair with {@link #stop()}. */
+    public void start() {
+        mResolver.registerContentObserver(mSettingUri, false, mObserver);
+        setParserValue();
+        update(mParser);
+    }
+
+    /** Stops observing changes for the setting. */
+    public void stop() {
+        mResolver.unregisterContentObserver(mObserver);
+    }
+
+    /**
+     * Returns the {@link String} representation of the setting. Subclasses should implement this
+     * for their setting.
+     */
+    public abstract String getSettingValue(ContentResolver resolver);
+
+    /** Updates the parser with the current setting value. */
+    private void setParserValue() {
+        String setting = getSettingValue(mResolver);
+        try {
+            mParser.setString(setting);
+        } catch (IllegalArgumentException e) {
+            Slog.e(TAG, "Malformed setting: " + setting);
+        }
+    }
+
+    /** Subclasses should implement this to update references to their parameters. */
+    public abstract void update(KeyValueListParser parser);
+
+    private class SettingObserver extends ContentObserver {
+        private SettingObserver(Handler handler) {
+            super(handler);
+        }
+
+        @Override
+        public void onChange(boolean selfChange) {
+            setParserValue();
+            update(mParser);
+        }
+    }
+}

core/java/com/android/internal/backup/LocalTransportParameters.java

@@ -16,62 +16,32 @@
 
 package com.android.internal.backup;
 
+import android.util.KeyValueSettingObserver;
 import android.content.ContentResolver;
-import android.database.ContentObserver;
 import android.os.Handler;
 import android.provider.Settings;
 import android.util.KeyValueListParser;
-import android.util.Slog;
 
-class LocalTransportParameters {
+class LocalTransportParameters extends KeyValueSettingObserver {
     private static final String TAG = "LocalTransportParams";
     private static final String SETTING = Settings.Secure.BACKUP_LOCAL_TRANSPORT_PARAMETERS;
     private static final String KEY_FAKE_ENCRYPTION_FLAG = "fake_encryption_flag";
 
-    private final KeyValueListParser mParser = new KeyValueListParser(',');
-    private final ContentObserver mObserver;
-    private final ContentResolver mResolver;
     private boolean mFakeEncryptionFlag;
 
     LocalTransportParameters(Handler handler, ContentResolver resolver) {
-        mObserver = new Observer(handler);
-        mResolver = resolver;
-    }
-
-    /** Observes for changes in the setting. This method MUST be paired with {@link #stop()}. */
-    void start() {
-        mResolver.registerContentObserver(Settings.Secure.getUriFor(SETTING), false, mObserver);
-        update();
-    }
-
-    /** Stop observing for changes in the setting. */
-    void stop() {
-        mResolver.unregisterContentObserver(mObserver);
+        super(handler, resolver, Settings.Secure.getUriFor(SETTING));
     }
 
     boolean isFakeEncryptionFlag() {
         return mFakeEncryptionFlag;
     }
 
-    private void update() {
-        String parameters = "";
-        try {
-            parameters = Settings.Secure.getString(mResolver, SETTING);
-        } catch (IllegalArgumentException e) {
-            Slog.e(TAG, "Malformed " + SETTING + " setting: " + e.getMessage());
-        }
-        mParser.setString(parameters);
-        mFakeEncryptionFlag = mParser.getBoolean(KEY_FAKE_ENCRYPTION_FLAG, false);
+    public String getSettingValue(ContentResolver resolver) {
+        return Settings.Secure.getString(resolver, SETTING);
     }
 
-    private class Observer extends ContentObserver {
-        private Observer(Handler handler) {
-            super(handler);
-        }
-
-        @Override
-        public void onChange(boolean selfChange) {
-            update();
-        }
+    public void update(KeyValueListParser parser) {
+        mFakeEncryptionFlag = parser.getBoolean(KEY_FAKE_ENCRYPTION_FLAG, false);
     }
 }