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      1 /*
      2 * Copyright (C) 2013 The Android Open Source Project
      3 *
      4 * Licensed under the Apache License, Version 2.0 (the "License");
      5 * you may not use this file except in compliance with the License.
      6 * You may obtain a copy of the License at
      7 *
      8 *      http://www.apache.org/licenses/LICENSE-2.0
      9 *
     10 * Unless required by applicable law or agreed to in writing, software
     11 * distributed under the License is distributed on an "AS IS" BASIS,
     12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13 * See the License for the specific language governing permissions and
     14 * limitations under the License.
     15 */
     16 
     17 package com.example.android.beamlargefiles;
     18 
     19 import android.app.Activity;
     20 import android.net.Uri;
     21 import android.nfc.NfcAdapter;
     22 import android.nfc.NfcEvent;
     23 import android.os.Bundle;
     24 import android.support.v4.app.Fragment;
     25 import android.util.Log;
     26 
     27 /**
     28  * This class demonstrates how to use Beam to send files too large to transfer reliably via NFC.
     29  *
     30  * <p>While any type of data can be placed into a normal NDEF messages, NFC is not considered
     31  * "high-speed" communication channel. Large images can easily take > 30 seconds to transfer.
     32  * Because NFC requires devices to be in extremely close proximity, this is not ideal.
     33  *
     34  * <p>Instead, Android 4.2+ devices can use NFC to perform an initial handshake, before handing
     35  * off to a faster communication channel, such as Bluetooth, for file transfer.
     36  *
     37  * <p>The tradeoff is that this application will not be invoked on the receiving device. Instead,
     38  * the transfer will be handled by the OS. The user will be shown a notification when the transfer
     39  * is complete. Selecting the notification will open the file in the default viewer for its MIME-
     40  * type. (If it's important that your application be used to open the file, you'll need to register
     41  * an intent-filter to watch for the appropriate MIME-type.)
     42  */
     43 public class BeamLargeFilesFragment extends Fragment implements NfcAdapter.CreateBeamUrisCallback {
     44 
     45     private static final String TAG = "BeamLargeFilesFragment";
     46     /** Filename that is to be sent for this activity. Relative to /assets. */
     47     private static final String FILENAME = "stargazer_droid.jpg";
     48     /** Content provider URI. */
     49     private static final String CONTENT_BASE_URI =
     50             "content://com.example.android.beamlargefiles.files/";
     51 
     52     /**
     53      * Standard lifecycle event. Registers a callback for large-file transfer, by calling
     54      * NfcAdapter.setBeamPushUrisCallback().
     55      *
     56      * Note: Like sending NDEF messages over standard Android Beam, there is also a non-callback
     57      * API available. See: NfcAdapter.setBeamPushUris().
     58      *
     59      * @param savedInstanceState Saved instance state.
     60      */
     61     @Override
     62     public void onCreate(Bundle savedInstanceState) {
     63         super.onCreate(savedInstanceState);
     64         setHasOptionsMenu(true);
     65         Activity a = getActivity();
     66 
     67         // Setup Beam to transfer a large file. Note the call to setBeamPushUrisCallback().
     68         // BEGIN_INCLUDE(setBeamPushUrisCallback)
     69         NfcAdapter nfc = NfcAdapter.getDefaultAdapter(a);
     70         if (nfc != null) {
     71             Log.w(TAG, "NFC available. Setting Beam Push URI callback");
     72             nfc.setBeamPushUrisCallback(this, a);
     73         } else {
     74             Log.w(TAG, "NFC is not available");
     75         }
     76         // END_INCLUDE(setBeamPushUrisCallback)
     77     }
     78 
     79     /**
     80      * Callback for Beam events (large file version). The return value here should be an array of
     81      * content:// or file:// URIs to send.
     82      *
     83      * Note that the system must have read access to whatever URIs are provided here.
     84      *
     85      * @param nfcEvent NFC event which triggered callback
     86      * @return URIs to be sent to remote device
     87      */
     88     // BEGIN_INCLUDE(createBeamUris)
     89     @Override
     90     public Uri[] createBeamUris(NfcEvent nfcEvent) {
     91         Log.i(TAG, "Beam event in progress; createBeamUris() called.");
     92         // Images are served using a content:// URI. See AssetProvider for implementation.
     93         Uri photoUri = Uri.parse(CONTENT_BASE_URI + FILENAME);
     94         Log.i(TAG, "Sending URI: " + photoUri);
     95         return new Uri[] {photoUri};
     96     }
     97     // END_INCLUDE(createBeamUris)
     98 }
     99