src/com/android/browser/NfcHandler.java

/*
 * Copyright (C) 2011 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 com.android.browser;

import android.app.Activity;
import android.nfc.NdefMessage;
import android.nfc.NdefRecord;
import android.nfc.NfcAdapter;
import android.os.AsyncTask;
import android.os.Handler;
import android.os.Message;

import java.util.concurrent.CountDownLatch;

/** This class implements sharing the URL of the currently
  * shown browser page over NFC. Sharing is only active
  * when the activity is in the foreground and resumed.
  * Incognito tabs will not be shared over NFC.
  */
public class NfcHandler implements NfcAdapter.NdefPushCallback {
    private NfcAdapter mNfcAdapter;
    private Activity mActivity;
    private Controller mController;
    private Handler mHandler;
    private Tab mCurrentTab;
    private boolean mIsPrivate;
    private CountDownLatch mPrivateBrowsingSignal;

    private static final int GET_PRIVATE_BROWSING_STATE_MSG = 100;

    public NfcHandler(Activity browser, Controller controller) {
        mActivity = browser;
        mController = controller;
        mNfcAdapter = NfcAdapter.getDefaultAdapter(mActivity);
        mHandler = new Handler() {
            @Override
            public void handleMessage(Message msg) {
                if (msg.what == GET_PRIVATE_BROWSING_STATE_MSG) {
                    mIsPrivate = mCurrentTab.getWebView().isPrivateBrowsingEnabled();
                    mPrivateBrowsingSignal.countDown();
                }
            }
        };
    }

    void onPause() {
        if (mNfcAdapter != null) {
            mNfcAdapter.disableForegroundNdefPush(mActivity);
        }
    }

    void onResume() {
        if (mNfcAdapter != null) {
            mNfcAdapter.enableForegroundNdefPush(mActivity, this);
        }
    }

    @Override
    public NdefMessage createMessage() {
        mCurrentTab = mController.getCurrentTab();
        if ((mCurrentTab != null) && (mCurrentTab.getWebView() != null)) {
            // We can only read the WebView state on the UI thread, so post
            // a message and wait.
            mPrivateBrowsingSignal = new CountDownLatch(1);
            mHandler.sendMessage(mHandler.obtainMessage(GET_PRIVATE_BROWSING_STATE_MSG));
            try {
                mPrivateBrowsingSignal.await();
            } catch (InterruptedException e) {
                return null;
            }
        }

        if ((mCurrentTab == null) || mIsPrivate) {
            return null;
        }

        String currentUrl = mCurrentTab.getUrl();
        if (currentUrl != null) {
            NdefRecord record = NdefRecord.createUri(currentUrl);
            NdefMessage msg = new NdefMessage(new NdefRecord[] { record });
            return msg;
        } else {
            return null;
        }
    }

    @Override
    public void onMessagePushed() {
    }
}