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diff --git a/docs/html/guide/topics/nfc/index.jd b/docs/html/guide/topics/nfc/index.jd index b486d3b..b86d72d 100644 --- a/docs/html/guide/topics/nfc/index.jd +++ b/docs/html/guide/topics/nfc/index.jd @@ -1,601 +1,33 @@ page.title=Near Field Communication @jd:body -<div id="qv-wrapper"> -<div id="qv"> - <h2>In this document</h2> - <ol> - <li><a href="#api">API Overview</a></li> - <li><a href="#manifest">Declaring Android Manifest elements</a></li> - <li><a href="#dispatch">The Tag Dispatch System</a> - <ol> - <li><a href="#intent-dispatch">Using the intent dispatch system</a></li> - <li><a href="#foreground-dispatch">Using the foreground dispatch system</a></li> - </ol></li> - <li><a href="#ndef">Working with Data on NFC Tags</a></li> - <li><a href="#read">Reading an NFC Tag</a></li> - <li><a href="#write">Writing to an NFC Tag</a></li> - <li><a href="#p2p">Peer-to-Peer Data Exchange</a></li> - </ol> -</div> -</div> - <p>Near Field Communication (NFC) is a set of short-range wireless technologies, typically - requiring a distance of 4cm or less. NFC operates at 13.56mhz, and at rates ranging from 106 - kbit/s to 848 kbit/s. NFC communication always involves an initiator and a target. The initiator - actively generates an RF field that can power a passive target. This enables NFC targets to take - very simple form factors such as tags, stickers or cards that do not require power. NFC - peer-to-peer communication is also possible, where both devices are powered.</p> - - <p>Compared to other wireless technologies such as Bluetooth or WiFi, NFC provides much lower - bandwidth and range, but enables low-cost, un-powered targets and does not require discovery or - pairing. Interactions can be initiated with just a tap.</p> + requiring a distance of 4cm or less to initiate a connection. NFC allows you to share small + payloads of data between an NFC tag and an Android-powered device, or between two Android-powered + devices. - <p>An Android device with NFC hardware will typically act as an initiator when the screen is on. - This mode is also known as NFC reader/writer. It will actively look for NFC tags and start - activities to handle them. Android 2.3.3 also has some limited P2P support.</p> - - <p>Tags can range in complexity, simple tags just offer read/write semantics, sometimes with + <p>Tags can range in complexity. Simple tags offer just read and write semantics, sometimes with one-time-programmable areas to make the card read-only. More complex tags offer math operations, and have cryptographic hardware to authenticate access to a sector. The most sophisticated tags - contain operating environments, allowing complex interactions with code executing on the tag.</p> - - <h2 id="api">API Overview</h2> - - <p>The {@link android.nfc} package contains the high-level classes to interact with the local - device's NFC adapter, to represent discovered tags, and to use the NDEF data format.</p> - - <table> - <tr> - <th>Class</th> - - <th>Description</th> - </tr> - - <tr> - <td>{@link android.nfc.NfcManager}</td> - - <td>A high level manager class that enumerates the NFC adapters on this Android device. Since - most Android devices only have one NFC adapter, you can just use the static helper {@link - android.nfc.NfcAdapter#getDefaultAdapter(Context)} for most situations.</td> - </tr> - - <tr> - <td>{@link android.nfc.NfcAdapter}</td> - - <td>Represents the local NFC adapter. Defines the intent's used to request tag dispatch to - your activity, and provides methods to register for foreground tag dispatch and foreground - NDEF push. Foreground NDEF push is the only peer-to-peer support that is currently provided - in Android.</td> - </tr> - - <tr> - <td>{@link android.nfc.NdefMessage} and {@link android.nfc.NdefRecord}</td> - - <td>NDEF is an NFC Forum defined data structure, designed to efficiently store data on NFC - tags, such as text, URL's, and other MIME types. A {@link android.nfc.NdefMessage} acts as a - container for the data that you want to transmit or read. One {@link android.nfc.NdefMessage} - object contains zero or more {@link android.nfc.NdefRecord}s. Each NDEF record has a type - such as text, URL, smart poster, or any MIME data. The type of the first NDEF record in the - NDEF message is used to dispatch a tag to an activity on Android.</td> - </tr> - - <tr> - <td>{@link android.nfc.Tag}</td> - - <td>Represents a passive NFC target. These can come in many form factors such as a tag, card, - key fob, or even a phone doing card emulation. When a tag is discovered, a {@link - android.nfc.Tag} object is created and wrapped inside an Intent. The NFC dispatch system - sends the intent to a compatible activity using <code>startActivity()</code>. You can use the - {@link android.nfc.Tag#getTechList getTechList()} method to determine the technologies - supported by this tag and create the corresponding {@link android.nfc.tech.TagTechnology} - object with one of classes provided by {@link android.nfc.tech}.</td> - </tr> - </table> - - <p>The {@link android.nfc.tech} package contains classes to query properties and perform I/O - operations on a tag. The classes are divided to represent different NFC technologies that can be - available on a Tag:</p> - - <table> - <tr> - <th>Class</th> - - <th>Description</th> - </tr> - - <tr> - <td>{@link android.nfc.tech.TagTechnology}</td> - - <td>The interface that all tag technology classes must implement.</td> - </tr> - - <tr> - <td>{@link android.nfc.tech.NfcA}</td> - - <td>Provides access to NFC-A (ISO 14443-3A) properties and I/O operations.</td> - </tr> - - <tr> - <td>{@link android.nfc.tech.NfcB}</td> - - <td>Provides access to NFC-B (ISO 14443-3B) properties and I/O operations.</td> - </tr> - - <tr> - <td>{@link android.nfc.tech.NfcF}</td> - - <td>Provides access to NFC-F (JIS 6319-4) properties and I/O operations.</td> - </tr> - - <tr> - <td>{@link android.nfc.tech.NfcV}</td> - - <td>Provides access to NFC-V (ISO 15693) properties and I/O operations.</td> - </tr> - - <tr> - <td>{@link android.nfc.tech.IsoDep}</td> - - <td>Provides access to ISO-DEP (ISO 14443-4) properties and I/O operations.</td> - </tr> - - <tr> - <td>{@link android.nfc.tech.Ndef}</td> - - <td>Provides access to NDEF data and operations on NFC tags that have been formatted as - NDEF.</td> - </tr> - - <tr> - <td>{@link android.nfc.tech.NdefFormatable}</td> - - <td>Provides a format operations for tags that may be NDEF formattable.</td> - </tr> - - <tr> - <td>{@link android.nfc.tech.MifareClassic}</td> - - <td>Provides access to MIFARE Classic properties and I/O operations, if this Android device - supports MIFARE.</td> - </tr> - - <tr> - <td>{@link android.nfc.tech.MifareUltralight}</td> - - <td>Provides access to MIFARE Ultralight properties and I/O operations, if this Android - device supports MIFARE.</td> - </tr> - </table> - - <h2 id="manifest">Declaring Android Manifest elements</h2> - - <p>Before you can access a device's NFC hardware and properly handle NFC intents, declare these - items in your <code>AndroidManifest.xml</code> file:</p> - - <ol> - <li>The NFC <code><uses-permission></code> element to access the NFC hardware: - <pre> -<uses-permission android:name="android.permission.NFC" /> -</pre> - </li> - - <li>The minimum SDK version that your application can support. API level 9 only supports - limited tag dispatch via {@link android.nfc.NfcAdapter#ACTION_TAG_DISCOVERED}, and only gives - access to NDEF messages via the {@link android.nfc.NfcAdapter#EXTRA_NDEF_MESSAGES} extra. No - other tag properties or I/O operations are accessible. You probably want to use API level 10 - which includes comprehensive reader/writer support. - <pre class="pretty-print"> -<uses-sdk android:minSdkVersion="10"/> -</pre> - </li> - - <li>The uses-feature element so that your application can show up in the Android Market for - devices that have NFC hardware: - <pre> -<uses-feature android:name="android.hardware.nfc" android:required="true" /> -</pre> - </li> - - <li>The NFC intent filter to tell the Android system your Activity can handle NFC data. Specify - one or more of these three intent filters: - <pre> -<intent-filter> - <action android:name="android.nfc.action.NDEF_DISCOVERED"/> - <data android:mimeType="<em>mime/type</em>" /> -</intent-filter> - -<intent-filter> - <action android:name="android.nfc.action.TECH_DISCOVERED"/> - <meta-data android:name="android.nfc.action.TECH_DISCOVERED" - android:resource="@xml/<em>nfc_tech_filter</em>.xml" /> -</intent-filter> - -<intent-filter> - <action android:name="android.nfc.action.TAG_DISCOVERED"/> -</intent-filter> -</pre> - - <p>The three intent filters are prioritized and behave in specific ways. Declare only the - ones that your Activity needs to handle. For more information on how to handle these filters, - see the section about <a href="#dispatch">The Tag Dispatch System</a>.</p> - </li> - </ol> - - <p>View the <a href= - "../../../resources/samples/NFCDemo/AndroidManifest.html">AndroidManifest.xml</a> from the - NFCDemo sample to see a complete example.</p> - - <h2 id="dispatch">The Tag Dispatch System</h2> - - <p>When an Android device scans an NFC tag, the desired behavior is to have the most appropriate - Activity handle the intent without asking the user what application to use. Because devices scan - NFC tags at a very short range, it is likely that making users manually select an Activity forces - them to move the device away from the tag and break the connection. You should develop your - Activity to only handle the NFC tags that your Activity cares about to prevent the Activity - Chooser from appearing. Android provides two systems to help you correctly identify an NFC tag - that your Activity should handle: the Intent dispatch system and the foreground Activity dispatch - system.</p> - - <p>The intent dispatch system checks the intent filters of all the Activities along with the - types of data that the Activities support to find the best Activity that can handle the NFC tag. - If multiple Activities specify the same intent filter and data to handle, then the Activity - Chooser is presented to the user as a last resort.</p> - - <p>The foreground dispatch system allows an Activity application to override the intent dispatch - system and have priority when an NFC tag is scanned. The Activity handling the request must be - running in the foreground of the device. When an NFC tag is scanned and matches the intent and - data type that the foreground dispatch Activity defines, the intent is immediately sent to the - Activity even if another Activity can handle the intent. If the Activity cannot handle the - intent, the foreground dispatch system falls back to the intent dispatch system.</p> - - <h3 id="intent-dispatch">Using the intent dispatch system</h3> - - <p>The intent dispatch system specifies three intents that each have a priority. The intents that - start when a device scans a tag depend on the type of tag scanned. In general, the intents are - started in the following manner:</p> - - <ul> - <li> - <code>android.nfc.action.NDEF_DISCOVERED</code>: This intent starts when a tag that contains - an NDEF payload is scanned. This is the highest priority intent. The Android system does not - let you specify this intent generically to handle all data types. You must specify - <code><data></code> elements in the <code>AndroidManifest.xml</code> along with this - intent to correctly handle NFC tags that start this intent. For example, to handle a - <code>NDEF_DISCOVERED</code> intent that contains plain text, specify the following filter in - your <code>AndroidManifest.xml</code> file: - <pre> -<intent-filter> - <action android:name="android.nfc.action.NDEF_DISCOVERED"/> - <data android:mimeType="text/plain" /> -</intent-filter> -</pre> - - <p>If the <code>NDEF_DISCOVERED</code> intent is started, the <code>TECH_DISCOVERED</code> - and <code>TAG_DISCOVERED</code> intents are not started. This intent does not start if an - unknown tag is scanned or if the tag does not contain an NDEF payload.</p> - </li> - - <li><code>android.nfc.action.TECH_DISCOVERED</code>: If the <code>NDEF_DISCOVERED</code> intent - does not start or is not filtered by any Activity on the device, this intent starts if the tag - is known. The <code>TECH_DISCOVERED</code> intent requires that you specify the technologies - that you want to support in an XML resource file. For more information, see the section about - <a href="#technology-resources">Specifying tag technologies to handle</a>.</li> - - <li><code>android.nfc.action.TAG_DISCOVERED</code>: This intent starts if no Activities handle - the <code>NDEF_DISCOVERED</code> and <code>TECH_DISCOVERED</code> intents or if the tag that is - scanned is unknown.</li> - </ul> - - <h4 id="tech">Specifying tag technologies to handle</h4> - - <p>If your Activity declares the <code>android.nfc.action.TECH_DISCOVERED</code> intent in your - <code>AndroidManifest.xml</code> file, you must create an XML resource file that specifies the - technologies that your Activity supports within a <code>tech-list</code> set. Your Activity is - considered a match if a <code>tech-list</code> set is a subset of the technologies that are - supported by the tag, which you can obtain by calling {@link android.nfc.Tag#getTechList - getTechList()}.</p> - - <p>For example, if the tag that is scanned supports MifareClassic, NdefFormatable, and NfcA, your - <code>tech-list</code> set must specify all three, two, or one of the technologies (and nothing - else) in order for your Activity to be matched.</p> - - <p>The following sample defines all of the technologies. You can remove the ones that you do not - need. Save this file (you can name it anything you wish) in the - <code><project-root>/res/xml</code> folder.</p> - <pre> -<resources xmlns:xliff="urn:oasis:names:tc:xliff:document:1.2"> - <tech-list> - <tech>android.nfc.tech.IsoDep</tech> - <tech>android.nfc.tech.NfcA</tech> - <tech>android.nfc.tech.NfcB</tech> - <tech>android.nfc.tech.NfcF</tech> - <tech>android.nfc.tech.NfcV</tech> - <tech>android.nfc.tech.Ndef</tech> - <tech>android.nfc.tech.NdefFormatable</tech> - <tech>android.nfc.tech.MifareClassic</tech> - <tech>android.nfc.tech.MifareUltralight</tech> - </tech-list> -</resources> -</pre> - - <p>You can also specify multiple <code>tech-list</code> sets. Each of the <code>tech-list</code> - sets is considered independently, and your Activity is considered a match if any single - <code>tech-list</code> set is a subset of the technologies that are returned by {@link - android.nfc.Tag#getTechList getTechList()}. This provides <code>AND</code> and <code>OR</code> - semantics for matching technologies. The following example matches tags that can support the - NfcA and Ndef technologies or can support the NfcB and Ndef technologies:</p> - <pre> -<resources xmlns:xliff="urn:oasis:names:tc:xliff:document:1.2"> - <tech-list> - <tech>android.nfc.tech.NfcA</tech> - <tech>android.nfc.tech.Ndef</tech> - </tech-list> -</resources> - -<resources xmlns:xliff="urn:oasis:names:tc:xliff:document:1.2"> - <tech-list> - <tech>android.nfc.tech.NfcB</tech> - <tech>android.nfc.tech.Ndef</tech> - </tech-list> -</resources> -</pre> - - <p>In your <code>AndroidManifest.xml</code> file, specify the resource file that you just created - in the <code><meta-data></code> element inside the <code><activity></code> - element like in the following example:</p> - <pre> -<activity> -... -<intent-filter> - <action android:name="android.nfc.action.TECH_DISCOVERED"/> -</intent-filter> - -<meta-data android:name="android.nfc.action.TECH_DISCOVERED" - android:resource="@xml/nfc_tech_filter" /> -... -</activity> -</pre> - - <h3 id="foreground-dispatch">Using the foreground dispatch system</h3> - - <p>The foreground dispatch system allows an Activity to intercept an intent and claim priority - over other Activities that handle the same intent. The system is easy to use and involves - constructing a few data structures for the Android system to be able to send the appropriate - intents to your application. To enable the foreground dispatch system:</p> - - <ol> - <li>Add the following code in the onCreate() method of your Activity: - - <ol type="a"> - <li>Create a {@link android.app.PendingIntent} object so the Android system can populate it - with the details of the tag when it is scanned - <pre> -PendingIntent pendingIntent = PendingIntent.getActivity( - this, 0, new Intent(this, getClass()).addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP), 0); -</pre> - </li> - - <li>Declare intent filters to handle the intents that you want to intercept. The foreground - dispatch system checks the specified intent filters with the intent that is received when - the device scans a tag. If they match, then your application handles the intent. If it does - not match, the foreground dispatch system falls back to the intent dispatch system. - Specifying a <code>null</code> array of intent filters and for the technology filters, you - receive a <code>TAG_DISCOVERED</code> intent for all tags discovered. Note that the snippet - below handles all MIME types. You should only handle the ones that you need. - <pre> - IntentFilter ndef = new IntentFilter(NfcAdapter.ACTION_NDEF_DISCOVERED); - try { - ndef.addDataType("*/*"); /* Handles all MIME based dispatches. - You should specify only the ones that you need. */ - } - catch (MalformedMimeTypeException e) { - throw new RuntimeException("fail", e); - } - intentFiltersArray = new IntentFilter[] { - ndef, - }; -</pre> - </li> - - <li>Set up an array of tag technologies that your application wants to handle. Call the - <code>Object.class.getName()</code> method to obtain the class of the technology that you - want to support. - <pre> - - techListsArray = new String[][] { new String[] { NfcF.class.getName() } }; - -</pre> - </li> - </ol> - </li> - - <li>Override the following Activity lifecycle callbacks and add logic to enable and disable the - foreground dispatch when the Activity loses ({@link android.app.Activity#onPause onPause()}) - and regains ({@link android.app.Activity#onResume onResume()}) focus. {@link - android.nfc.NfcAdapter#enableForegroundDispatch} must be called from the main thread and only - when the activity is in the foreground (calling in {@link android.app.Activity#onResume - onResume()} guarantees this). You also need to implement the {@link - android.app.Activity#onNewIntent onNewIntent} callback to process the data from the scanned NFC - tag. - <pre> -public void onPause() { - super.onPause(); - mAdapter.disableForegroundDispatch(this); -} - -public void onResume() { - super.onResume(); - mAdapter.enableForegroundDispatch(this, pendingIntent, intentFiltersArray, techListsArray); -} - -public void onNewIntent(Intent intent) { - Tag tagFromIntent = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG); - //do something with tagFromIntent -} -</pre> - </li> - </ol> - - <p>See the <a href= - "{@docRoot}resources/samples/ApiDemos/src/com/example/android/apis/nfc/ForegroundDispatch.html">ForegroundDispatch</a> - sample from API Demos for the complete sample.</p> - - <h2 id="ndef">Working with Data on NFC Tags</h2> - - <p>Data on NFC tags are encoded in raw bytes, so you must convert the bytes to something human - readable if you are presenting the data to the user. When writing to NFC tags, you must write - them in bytes as well. Android provides APIs to help write messages that conform to the NDEF - standard, which was developed by the <a href="http://www.nfc-forum.org/specs/">NFC Forum</a> to - standardized data on tags. Using this standard ensures that your data will be supported by all - Android NFC devices if you are writing to tags. However, many tag technologies use their own - standard for storing data and are supported by Android as well, but you have to implement your - own protocol stack to read and write to these tags. You can find a full list of the supported - technologies in {@link android.nfc.tech} and an overview of the technologies in the {@link - android.nfc.tech.TagTechnology} interface. This section is a brief overview of how to work with - NDEF messages in the context of the Android system. It is not meant to be a complete discussion - of the NDEF specification, but highlights the main things that you need to be aware of when - working with NDEF messages in Android.</p> - - <p>To facilitate working with NDEF messages, Android provides the {@link android.nfc.NdefRecord} - and {@link android.nfc.NdefMessage} to encapsulate the raw bytes that represent NDEF messages. An - {@link android.nfc.NdefMessage} is the container for zero or more {@link - android.nfc.NdefRecord}s. Each {@link android.nfc.NdefRecord} has its own unique type name - format, record type, and ID to distinguish them from other records within the same {@link - android.nfc.NdefMessage}. You can store different types of records of varying length in a single - {@link android.nfc.NdefMessage}. The size constraint of the NFC tag determines how big your - {@link android.nfc.NdefMessage} can be.</p> - - <p>Tags that support the {@link android.nfc.tech.Ndef} and {@link - android.nfc.tech.NdefFormatable} technologies return and accept {@link android.nfc.NdefMessage} - objects as parameters for read and write operations. You need to create your own logic to read - and write bytes for other tag technologies in {@link android.nfc.tech}.</p> - - <p>You can download technical specifications for different types of NDEF message standards, such - as plain text and Smart Posters, at the <a href="http://www.nfc-forum.org/specs/">NFC Forum</a> - website. The NFCDemo sample application also declares sample <a href= - "{@docRoot}resources/samples/NFCDemo/src/com/example/android/nfc/simulator/MockNdefMessages.html"> - plain text and SmartPoster NDEF messages.</a></p> - - <h2 id="read">Reading an NFC Tag</h2> - - <p>When a device comes in proximity to an NFC tag, the appropriate intent is started on the - device, notifying interested applications that a NFC tag was scanned. By previously declaring the - appropriate intent filter in your <code>AndroidManifest.xml</code> file or using foreground - dispatching, your application can request to handle the intent.</p> - - <p>The following method (slightly modified from the NFCDemo sample application), handles the - <code>TAG_DISCOVERED</code> intent and iterates through an array obtained from the intent that - contains the NDEF payload:</p> - <pre> -NdefMessage[] getNdefMessages(Intent intent) { - // Parse the intent - NdefMessage[] msgs = null; - String action = intent.getAction(); - if (NfcAdapter.ACTION_TAG_DISCOVERED.equals(action)) { - Parcelable[] rawMsgs = intent.getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES); - if (rawMsgs != null) { - msgs = new NdefMessage[rawMsgs.length]; - for (int i = 0; i < rawMsgs.length; i++) { - msgs[i] = (NdefMessage) rawMsgs[i]; - } - } - else { - // Unknown tag type - byte[] empty = new byte[] {}; - NdefRecord record = new NdefRecord(NdefRecord.TNF_UNKNOWN, empty, empty, empty); - NdefMessage msg = new NdefMessage(new NdefRecord[] {record}); - msgs = new NdefMessage[] {msg}; - } - } - else { - Log.e(TAG, "Unknown intent " + intent); - finish(); - } - return msgs; -} -</pre> - - <p>Keep in mind that the data that the device reads is in bytes, so you must implement your own - logic if you need to present the data in a readable format to the user. The classes in - <code>com.example.android.nfc.record</code> of the NFCDemo sample show you how to parse some - common types of NDEF messages such as plain text or a SmartPoster.</p> - - <h2 id="write">Writing to an NFC Tag</h2> - - <p>Writing to an NFC tag involves constructing your NDEF message in bytes and using the - appropriate tag technology for the tag that you are writing to. The following code sample shows - you how to write a simple text message to a {@link android.nfc.tech.NdefFormatable} tag:</p> - <pre> -NdefFormatable tag = NdefFormatable.get(t); -Locale locale = Locale.US; -final byte[] langBytes = locale.getLanguage().getBytes(Charsets.US_ASCII); -String text = "Tag, you're it!"; -final byte[] textBytes = text.getBytes(Charsets.UTF_8); -final int utfBit = 0; -final char status = (char) (utfBit + langBytes.length); -final byte[] data = Bytes.concat(new byte[] {(byte) status}, langBytes, textBytes); -NdefRecord record = NdefRecord(NdefRecord.TNF_WELL_KNOWN, NdefRecord.RTD_TEXT, new byte[0], data); -try { - NdefRecord[] records = {text}; - NdefMessage message = new NdefMessage(records); - tag.connect(); - tag.format(message); -} -catch (Exception e){ - //do error handling -} -</pre> - - <h2 id="p2p">Peer-to-Peer Data Exchange</h2> - - <p>Support for simple peer-to-peer data exchange is supported by the foreground push feature, - which is enabled with the {@link android.nfc.NfcAdapter#enableForegroundNdefPush} method. To use - this feature:</p> - - <ul> - <li>The Activity that is pushing the data must be in the foreground</li> - - <li>You must encapsulate the data that you are sending in an {@link android.nfc.NdefMessage} - object</li> - - <li>The NFC device that is receiving the pushed data (the scanned device) must support the - <code>com.android.npp</code> NDEF push protocol, which is optional for Android devices.</li> - </ul> - - <p class="note">If your Activity enables the foreground push feature and is in the foreground, - the standard intent dispatch system is disabled. However, if your Activity also enables - foreground dispatching, then it can still scan tags that match the intent filters set in the - foreground dispatching.</p> - - <p>To enable foreground dispatching:</p> - - <ol> - <li>Create an NdefMessage that contains the NdefRecords that you want to push onto the other - device.</li> - - <li>Implement the {@link android.app.Activity#onResume onResume()} and {@link - android.app.Activity#onPause onPause()} callbacks in your Activity to appropriately handle the - foreground pushing lifecycle. You must call {@link - android.nfc.NfcAdapter#enableForegroundNdefPush} from the main thread and only when the - activity is in the foreground (calling in {@link android.app.Activity#onResume onResume()} - guarantees this). - <pre> -public void onResume() { - super.onResume(); - if (mAdapter != null) - mAdapter.enableForegroundNdefPush(this, myNdefMessage); -} -public void onPause() { - super.onPause(); - if (mAdapter != null) - mAdapter.disableForegroundNdefPush(this); -} -</pre> - </li> - </ol> - - <p>When the Activity is in the foreground, you can now tap the device to another device and push - the data to it. See the <a href= - "../../../resources/samples/ApiDemos/src/com/example/android/apis/nfc/ForegroundNdefPush.html">ForegroundNdefPush</a> - sample in API Demos for a simple example of peer-to-peer data exchange.</p>
\ No newline at end of file + contain operating environments, allowing complex interactions with code executing on the tag. + The data stored in the tag can also be written in a variety of formats, but many of the Android + framework APIs are based around a <a href="http://www.nfc-forum.org/">NFC Forum</a> standard + called NDEF (NFC Data Exchange Format).</p> + + <dl> + <dt><strong><a href="{@docRoot}guide/topics/nfc/nfc.html">NFC Basics</a></strong></dt> + <dd>This document describes how Android handles discovered NFC tags and how it notifies +applications of data that is relevant to the application. It also goes over how to work with the +NDEF data in your applications and gives an overview of the framework APIs that support the basic +NFC feature set of Android.</dd> + + <dt><strong><a href="{@docRoot}guide/topics/nfc/advanced-nfc.html">Advanced + NFC</a></strong></dt> + <dd>This document goes over the APIs that enable use of the various tag technologies that + Android supports. When you are not working with NDEF data, or when you are working with NDEF + data that Android cannot fully understand, you have to manually read or write to the tag in raw + bytes using your own protocol stack. In these cases, Android provides support to detect + certain tag technologies and to open communication with the tag using your own protocol + stack.</dd> + </dl> +</p>
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