[Android] Add Java observers to the NetworkChangeNotifier

net/android/java/src/org/chromium/net/NetworkChangeNotifier.java

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.net;
 
 import android.content.Context;
 
 import org.chromium.base.CalledByNative;
 import org.chromium.base.JNINamespace;
 import org.chromium.base.NativeClassQualifiedName;
 
+import java.util.ArrayList;
+
 /**
- * Triggers updates to the underlying network state in native Chrome.
+ * Triggers updates to the underlying network state in Chrome.
  * By default, connectivity is assumed and changes must pushed from
  * the embedder via the forceConnectivityState function.
  * Embedders may choose to have this class auto-detect changes in
  * network connectivity by invoking the autoDetectConnectivityState
  * function.

[nilesh, 2012/09/22 00:40:24]

WOrth adding that this class is not thread safe.

[gone, 2012/09/24 18:28:24]

Done.

  */
 @JNINamespace("net")
 public class NetworkChangeNotifier {
+    /** Alerted when the connection type of the network changes. */

[nilesh, 2012/09/22 00:40:24]

Please add a comment.
onConnectionTypeChanged will be called on the UI thread.

[gone, 2012/09/24 18:28:24]

Done.

+    public interface ConnectionTypeObserver {
+        public void onConnectionTypeChanged(int connectionType);
+    }
+
     // These constants must always match the ones in network_change_notifier.h.
     public static final int CONNECTION_UNKNOWN = 0;
     public static final int CONNECTION_ETHERNET = 1;
     public static final int CONNECTION_WIFI = 2;
     public static final int CONNECTION_2G = 3;
     public static final int CONNECTION_3G = 4;
     public static final int CONNECTION_4G = 5;
     public static final int CONNECTION_NONE = 6;
 
     private final Context mContext;
     private int mNativeChangeNotifier;
+    private ArrayList<ConnectionTypeObserver> mConnectionTypeObservers;
     private NetworkChangeNotifierAutoDetect mAutoDetector;
 
     private static NetworkChangeNotifier sInstance;
 
-    // Private constructor - instances are only created via the create factory
-    // function, which is only called from native.
     private NetworkChangeNotifier(Context context, int nativeChangeNotifier) {
         mContext = context;
         mNativeChangeNotifier = nativeChangeNotifier;
+        mConnectionTypeObservers = new ArrayList<ConnectionTypeObserver>();
     }
 
     private void destroy() {
         if (mAutoDetector != null) {
             mAutoDetector.destroy();
         }
         mNativeChangeNotifier = 0;
+        mConnectionTypeObservers.clear();
     }
 
     /**
      * Creates the singleton used by the native-side NetworkChangeNotifier.
      */
     @CalledByNative
     static NetworkChangeNotifier createInstance(Context context, int nativeChangeNotifier) {
         assert sInstance == null;
         sInstance = new NetworkChangeNotifier(context, nativeChangeNotifier);
         return sInstance;
@@ skipping 75 matching lines @@
             return;
         }
         boolean connectionCurrentlyExists =
             nativeGetConnectionType(mNativeChangeNotifier) != CONNECTION_NONE;
         if (connectionCurrentlyExists != forceOnline) {
             notifyObserversOfConnectionTypeChange(
                     forceOnline ? CONNECTION_UNKNOWN : CONNECTION_NONE);
         }
     }
 
+    /**
+     * Alerts all observers of a connection change.
+     */
     void notifyObserversOfConnectionTypeChange(int newConnectionType) {
         if (mNativeChangeNotifier != 0) {
             nativeNotifyObserversOfConnectionTypeChange(mNativeChangeNotifier, newConnectionType);
         }
+
+        for (ConnectionTypeObserver observer : mConnectionTypeObservers) {
+            observer.onConnectionTypeChanged(newConnectionType);
+        }
+    }
+
+    /**
+     * Adds an observer for any connection type changes.
+     */
+    public static void addConnectionTypeObserver(ConnectionTypeObserver observer) {

[nilesh, 2012/09/22 00:40:24]

No removeConnectionTypeObserver ?
I think this is restrictive, and puts unnecessary limits on the lifecycle of the
observer.

[gone, 2012/09/24 18:28:24]

Done.

+        assert sInstance != null;
+        sInstance.addConnectionTypeObserverInternal(observer);
+    }
+
+    private void addConnectionTypeObserverInternal(ConnectionTypeObserver observer) {
+        mConnectionTypeObservers.add(observer);
     }
 
     @NativeClassQualifiedName("NetworkChangeNotifierAndroid")
     private native void nativeNotifyObserversOfConnectionTypeChange(
             int nativePtr, int newConnectionType);
 
     @NativeClassQualifiedName("NetworkChangeNotifierAndroid")
     private native int nativeGetConnectionType(int nativePtr);
 
     // For testing only.
     public static NetworkChangeNotifierAutoDetect getAutoDetectorForTest() {
         assert sInstance != null;
         return sInstance.mAutoDetector;
     }
 }