import android.content.IntentFilter;
import android.content.pm.IPackageManager;
import android.content.pm.PackageManager;
+import android.nfc.tech.MifareClassic;
+import android.nfc.tech.Ndef;
+import android.nfc.tech.NfcA;
+import android.nfc.tech.NfcF;
import android.os.IBinder;
-import android.os.Parcel;
import android.os.RemoteException;
import android.os.ServiceManager;
import android.util.Log;
/**
* Intent to start an activity when a tag with NDEF payload is discovered.
- * If the tag has and NDEF payload this intent is started before
- * {@link #ACTION_TECH_DISCOVERED}.
*
- * If any activities respond to this intent neither
+ * <p>The system inspects the first {@link NdefRecord} in the first {@link NdefMessage} and
+ * looks for a URI, SmartPoster, or MIME record. If a URI or SmartPoster record is found the
+ * intent will contain the URI in its data field. If a MIME record is found the intent will
+ * contain the MIME type in its type field. This allows activities to register
+ * {@link IntentFilter}s targeting specific content on tags. Activities should register the
+ * most specific intent filters possible to avoid the activity chooser dialog, which can
+ * disrupt the interaction with the tag as the user interacts with the screen.
+ *
+ * <p>If the tag has an NDEF payload this intent is started before
+ * {@link #ACTION_TECH_DISCOVERED}. If any activities respond to this intent neither
* {@link #ACTION_TECH_DISCOVERED} or {@link #ACTION_TAG_DISCOVERED} will be started.
*/
@SdkConstant(SdkConstantType.ACTIVITY_INTENT_ACTION)
public static final String ACTION_NDEF_DISCOVERED = "android.nfc.action.NDEF_DISCOVERED";
/**
- * Intent to started when a tag is discovered. The data URI is formated as
- * {@code vnd.android.nfc://tag/} with the path having a directory entry for each technology
- * in the {@link Tag#getTechList()} is sorted ascending order.
+ * Intent to start an activity when a tag is discovered and activities are registered for the
+ * specific technologies on the tag.
+ *
+ * <p>To receive this intent an activity must include an intent filter
+ * for this action and specify the desired tech types in a
+ * manifest <code>meta-data</code> entry. Here is an example manfiest entry:
+ * <pre>
+ * <activity android:name=".nfc.TechFilter" android:label="NFC/TechFilter">
+ * <!-- Add a technology filter -->
+ * <intent-filter>
+ * <action android:name="android.nfc.action.TECH_DISCOVERED" />
+ * </intent-filter>
+ *
+ * <meta-data android:name="android.nfc.action.TECH_DISCOVERED"
+ * android:resource="@xml/filter_nfc"
+ * />
+ * </activity>
+ * </pre>
+ *
+ * <p>The meta-data XML file should contain one or more <code>tech-list</code> entries
+ * each consisting or one or more <code>tech</code> entries. The <code>tech</code> entries refer
+ * to the qualified class name implementing the technology, for example "android.nfc.tech.NfcA".
*
- * This intent is started after {@link #ACTION_NDEF_DISCOVERED} and before
- * {@link #ACTION_TAG_DISCOVERED}
+ * <p>A tag matches if any of the
+ * <code>tech-list</code> sets is a subset of {@link Tag#getTechList() Tag.getTechList()}. Each
+ * of the <code>tech-list</code>s is considered independently and the
+ * activity is considered a match is any single <code>tech-list</code> matches the tag that was
+ * discovered. This provides AND and OR semantics for filtering desired techs. Here is an
+ * example that will match any tag using {@link NfcF} or any tag using {@link NfcA},
+ * {@link MifareClassic}, and {@link Ndef}:
*
- * If any activities respond to this intent {@link #ACTION_TAG_DISCOVERED} will not be started.
+ * <pre>
+ * <resources xmlns:xliff="urn:oasis:names:tc:xliff:document:1.2">
+ * <!-- capture anything using NfcF -->
+ * <tech-list>
+ * <tech>android.nfc.tech.NfcF</tech>
+ * </tech-list>
+ *
+ * <!-- OR -->
+ *
+ * <!-- capture all MIFARE Classics with NDEF payloads -->
+ * <tech-list>
+ * <tech>android.nfc.tech.NfcA</tech>
+ * <tech>android.nfc.tech.MifareClassic</tech>
+ * <tech>android.nfc.tech.Ndef</tech>
+ * </tech-list>
+ * </resources>
+ * </pre>
+ *
+ * <p>This intent is started after {@link #ACTION_NDEF_DISCOVERED} and before
+ * {@link #ACTION_TAG_DISCOVERED}. If any activities respond to {@link #ACTION_NDEF_DISCOVERED}
+ * this intent will not be started. If any activities respond to this intent
+ * {@link #ACTION_TAG_DISCOVERED} will not be started.
*/
@SdkConstant(SdkConstantType.ACTIVITY_INTENT_ACTION)
public static final String ACTION_TECH_DISCOVERED = "android.nfc.action.TECH_DISCOVERED";
/**
* Intent to start an activity when a tag is discovered.
+ *
+ * <p>This intent will not be started when a tag is discovered if any activities respond to
+ * {@link #ACTION_NDEF_DISCOVERED} or {@link #ACTION_TECH_DISCOVERED} for the current tag.
*/
@SdkConstant(SdkConstantType.ACTIVITY_INTENT_ACTION)
public static final String ACTION_TAG_DISCOVERED = "android.nfc.action.TAG_DISCOVERED";
public static final String ACTION_TAG_LEFT_FIELD = "android.nfc.action.TAG_LOST";
/**
- * Mandatory Tag extra for the ACTION_TAG intents.
+ * Mandatory extra containing the {@link Tag} that was discovered for the
+ * {@link #ACTION_NDEF_DISCOVERED}, {@link #ACTION_TECH_DISCOVERED}, and
+ * {@link #ACTION_TAG_DISCOVERED} intents.
*/
public static final String EXTRA_TAG = "android.nfc.extra.TAG";
/**
- * Optional NdefMessage[] extra for the ACTION_TAG intents.
+ * Optional extra containing an array of {@link NdefMessage} present on the discovered tag for
+ * the {@link #ACTION_NDEF_DISCOVERED}, {@link #ACTION_TECH_DISCOVERED}, and
+ * {@link #ACTION_TAG_DISCOVERED} intents.
*/
public static final String EXTRA_NDEF_MESSAGES = "android.nfc.extra.NDEF_MESSAGES";
/**
- * Optional byte[] extra for the tag identifier.
+ * Optional extra containing a byte array containing the ID of the discovered tag for
+ * the {@link #ACTION_NDEF_DISCOVERED}, {@link #ACTION_TECH_DISCOVERED}, and
+ * {@link #ACTION_TAG_DISCOVERED} intents.
*/
public static final String EXTRA_ID = "android.nfc.extra.ID";
* <p>
* {@link Tag} is an immutable object that represents the state of a NFC tag at
* the time of discovery. It can be used as a handle to {@link TagTechnology} classes
- * to perform advanced operations, or directly queried for its ID ({@link #getId} and the
- * set of technologies it contains ({@link #getTechList}). Arrays passed to and
- * returned by this class are *not* cloned, so be careful not to modify them.
+ * to perform advanced operations, or directly queried for its ID via {@link #getId} and the
+ * set of technologies it contains via {@link #getTechList}. Arrays passed to and
+ * returned by this class are <em>not</em> cloned, so be careful not to modify them.
* <p>
* A new tag object is created every time a tag is discovered (comes into range), even
* if it is the same physical tag. If a tag is removed and then returned into range, then
*
* <h3>Tag Dispatch</h3>
* When a tag is discovered, a {@link Tag} object is created and passed to a
- * single application via the {@link NfcAdapter#EXTRA_TAG} extra in a
- * {@link Context#startActivity} {@link android.content.Intent}. A four stage dispatch is used to select the
- * most appropriate application to handle the tag. The Android OS executes each stage in order,
- * and completes dispatch as soon as a single matching application is found. If there are multiple
- * matching applications found at any one stage then the Android Activity Chooser dialog is shown
- * to allow the user to select the application.
+ * single activity via the {@link NfcAdapter#EXTRA_TAG} extra in an
+ * {@link android.content.Intent} via {@link Context#startActivity}. A four stage dispatch is used
+ * to select the
+ * most appropriate activity to handle the tag. The Android OS executes each stage in order,
+ * and completes dispatch as soon as a single matching activity is found. If there are multiple
+ * matching activities found at any one stage then the Android activity chooser dialog is shown
+ * to allow the user to select the activity to receive the tag.
+ *
+ * <p>The Tag dispatch mechanism was designed to give a high probability of dispatching
+ * a tag to the correct activity without showing the user an activity chooser dialog.
+ * This is important for NFC interactions because they are very transient -- if a user has to
+ * move the Android device to choose an application then the connection will likely be broken.
+ *
* <h4>1. Foreground activity dispatch</h4>
- * A foreground activity that has called {@link NfcAdapter#enableForegroundDispatch} is
- * given priority. See the documentation on {#link NfcAdapter#enableForegroundDispatch} for
+ * A foreground activity that has called
+ * {@link NfcAdapter#enableForegroundDispatch NfcAdapter.enableForegroundDispatch()} is
+ * given priority. See the documentation on
+ * {@link NfcAdapter#enableForegroundDispatch NfcAdapter.enableForegroundDispatch()} for
* its usage.
* <h4>2. NDEF data dispatch</h4>
- * If the tag contains NDEF data, then {@link Context#startActivity} is called with
- * {@link NfcAdapter#ACTION_NDEF_DISCOVERED} and a data URI determined from the
- * first NDEF Record in the first NDEF Message in the Tag. This allows NDEF tags to be given
- * priority dispatch to applications that can handle the content.
+ * If the tag contains NDEF data the system inspects the first {@link NdefRecord} in the first
+ * {@link NdefMessage}. If the record is a URI, SmartPoster, or MIME data
+ * {@link Context#startActivity} is called with {@link NfcAdapter#ACTION_NDEF_DISCOVERED}. For URI
+ * and SmartPoster records the URI is put into the intent's data field. For MIME records the MIME
+ * type is put in the intent's type field. This allows activities to register to be launched only
+ * when data they know how to handle is present on a tag. This is the preferred method of handling
+ * data on a tag since NDEF data can be stored on many types of tags and doesn't depend on a
+ * specific tag technology.
* See {@link NfcAdapter#ACTION_NDEF_DISCOVERED} for more detail. If the tag does not contain
- * NDEF data, or if no application is registered
- * for {@link NfcAdapter#ACTION_NDEF_DISCOVERED} with a matching data URI then dispatch moves
- * to stage 3.
+ * NDEF data, or if no activity is registered
+ * for {@link NfcAdapter#ACTION_NDEF_DISCOVERED} with a matching data URI or MIME type then dispatch
+ * moves to stage 3.
* <h4>3. Tag Technology dispatch</h4>
* {@link Context#startActivity} is called with {@link NfcAdapter#ACTION_TECH_DISCOVERED} to
- * dispatch the tag to an application that can handle the technologies present on the tag.
+ * dispatch the tag to an activity that can handle the technologies present on the tag.
* Technologies are defined as sub-classes of {@link TagTechnology}, see the package
- * {@link android.nfc.tech}. The Android OS looks for an application that can handle one or
- * more technologies in the tag. See {@link NfcAdapter#ACTION_TECH_DISCOVERED for more detail.
+ * {@link android.nfc.tech}. The Android OS looks for an activity that can handle one or
+ * more technologies in the tag. See {@link NfcAdapter#ACTION_TECH_DISCOVERED} for more detail.
* <h4>4. Fall-back dispatch</h4>
- * If no application has been matched, then {@link Context#startActivity} is called with
+ * If no activity has been matched then {@link Context#startActivity} is called with
* {@link NfcAdapter#ACTION_TAG_DISCOVERED}. This is intended as a fall-back mechanism.
* See {@link NfcAdapter#ACTION_TAG_DISCOVERED}.
*
- * <p>
- * <i>The Tag dispatch mechanism was designed to give a high probability of dispatching
- * a tag to the correct application without showing the user an Application Chooser dialog.
- * This is important for NFC interactions because they are very transient - if a user has to
- * move the Android device to choose an application then the connection is broken.</i>
- *
* <h3>NFC Tag Background</h3>
* An NFC tag is a passive NFC device, powered by the NFC field of this Android device while
- * it is in range. Tag's can come in many forms, such as stickers, cards, key fob, or
+ * it is in range. Tag's can come in many forms, such as stickers, cards, key fobs, or
* even embedded in a more sophisticated device.
* <p>
* Tags can have a wide range of capabilities. Simple tags just offer read/write semantics,
* and contain some one time
* programmable areas to make read-only. More complex tags offer math operations
* and per-sector access control and authentication. The most sophisticated tags
- * contain operating environments such as Javacard, allowing complex interactions with the
- * applets executing on the tag. Use {@link TagTechnology} classes to access a broad
+ * contain operating environments allowing complex interactions with the
+ * code executing on the tag. Use {@link TagTechnology} classes to access a broad
* range of capabilities available in NFC tags.
* <p>
*/
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