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
onCreate(Bundle savedInstanceState)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
createBeamUris(NfcEvent nfcEvent)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