Initial Contribution

1 files changed, 138 insertions, 0 deletions

diff --git a/core/java/android/database/ContentObserver.java b/core/java/android/database/ContentObserver.java
new file mode 100644
index 0000000..3b829a3
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+++ b/core/java/android/database/ContentObserver.java
@@ -0,0 +1,138 @@
+/*
+ * Copyright (C) 2007 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.database;
+
+import android.os.Handler;
+
+/**
+ * Receives call backs for changes to content. Must be implemented by objects which are added
+ * to a {@link ContentObservable}.
+ */
+public abstract class ContentObserver {
+
+    private Transport mTransport;
+
+    // Protects mTransport
+    private Object lock = new Object();
+
+    /* package */ Handler mHandler;
+
+    private final class NotificationRunnable implements Runnable {
+
+        private boolean mSelf;
+
+        public NotificationRunnable(boolean self) {
+            mSelf = self;
+        }
+
+        public void run() {
+            ContentObserver.this.onChange(mSelf);
+        }
+    }
+
+    private static final class Transport extends IContentObserver.Stub {
+        ContentObserver mContentObserver;
+
+        public Transport(ContentObserver contentObserver) {
+            mContentObserver = contentObserver;
+        }
+
+        public boolean deliverSelfNotifications() {
+            ContentObserver contentObserver = mContentObserver;
+            if (contentObserver != null) {
+                return contentObserver.deliverSelfNotifications();
+            }
+            return false;
+        }
+
+        public void onChange(boolean selfChange) {
+            ContentObserver contentObserver = mContentObserver;
+            if (contentObserver != null) {
+                contentObserver.dispatchChange(selfChange);
+            }
+        }
+
+        public void releaseContentObserver() {
+            mContentObserver = null;
+        }
+    }
+
+    /**
+     * onChange() will happen on the provider Handler.
+     *
+     * @param handler The handler to run {@link #onChange} on.
+     */
+    public ContentObserver(Handler handler) {
+        mHandler = handler;
+    }
+
+    /**
+     * Gets access to the binder transport object. Not for public consumption.
+     *
+     * {@hide}
+     */
+    public IContentObserver getContentObserver() {
+        synchronized(lock) {
+            if (mTransport == null) {
+                mTransport = new Transport(this);
+            }
+            return mTransport;
+        }
+    }
+
+    /**
+     * Gets access to the binder transport object, and unlinks the transport object
+     * from the ContentObserver. Not for public consumption.
+     *
+     * {@hide}
+     */
+    public IContentObserver releaseContentObserver() {
+        synchronized(lock) {
+            Transport oldTransport = mTransport;
+            if (oldTransport != null) {
+                oldTransport.releaseContentObserver();
+                mTransport = null;
+            }
+            return oldTransport;
+        }
+    }
+
+    /**
+     * Returns true if this observer is interested in notifications for changes
+     * made through the cursor the observer is registered with.
+     */
+    public boolean deliverSelfNotifications() {
+        return false;
+    }
+
+    /**
+     * This method is called when a change occurs to the cursor that
+     * is being observed.
+     *  
+     * @param selfChange true if the update was caused by a call to <code>commit</code> on the
+     *  cursor that is being observed.
+     */
+    public void onChange(boolean selfChange) {}
+
+    public final void dispatchChange(boolean selfChange) {
+        if (mHandler == null) {
+            onChange(selfChange);
+        } else {
+            mHandler.post(new NotificationRunnable(selfChange));
+        }
+    }
+}