Loading core/java/android/nfc/NfcAdapter.java +79 −15 Original line number Original line Diff line number Diff line Loading @@ -26,8 +26,11 @@ import android.content.Context; import android.content.IntentFilter; import android.content.IntentFilter; import android.content.pm.IPackageManager; import android.content.pm.IPackageManager; import android.content.pm.PackageManager; 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.IBinder; import android.os.Parcel; import android.os.RemoteException; import android.os.RemoteException; import android.os.ServiceManager; import android.os.ServiceManager; import android.util.Log; import android.util.Log; Loading @@ -43,30 +46,85 @@ public final class NfcAdapter { /** /** * Intent to start an activity when a tag with NDEF payload is discovered. * 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. * {@link #ACTION_TECH_DISCOVERED} or {@link #ACTION_TAG_DISCOVERED} will be started. */ */ @SdkConstant(SdkConstantType.ACTIVITY_INTENT_ACTION) @SdkConstant(SdkConstantType.ACTIVITY_INTENT_ACTION) public static final String ACTION_NDEF_DISCOVERED = "android.nfc.action.NDEF_DISCOVERED"; 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 * Intent to start an activity when a tag is discovered and activities are registered for the * {@code vnd.android.nfc://tag/} with the path having a directory entry for each technology * specific technologies on the tag. * in the {@link Tag#getTechList()} is sorted ascending order. * * * <p>To receive this intent an activity must include an intent filter * This intent is started after {@link #ACTION_NDEF_DISCOVERED} and before * for this action and specify the desired tech types in a * {@link #ACTION_TAG_DISCOVERED} * manifest <code>meta-data</code> entry. Here is an example manfiest entry: * * <pre> * If any activities respond to this intent {@link #ACTION_TAG_DISCOVERED} will not be started. * <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". * * <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}: * * <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) @SdkConstant(SdkConstantType.ACTIVITY_INTENT_ACTION) public static final String ACTION_TECH_DISCOVERED = "android.nfc.action.TECH_DISCOVERED"; public static final String ACTION_TECH_DISCOVERED = "android.nfc.action.TECH_DISCOVERED"; /** /** * Intent to start an activity when a tag is 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) @SdkConstant(SdkConstantType.ACTIVITY_INTENT_ACTION) public static final String ACTION_TAG_DISCOVERED = "android.nfc.action.TAG_DISCOVERED"; public static final String ACTION_TAG_DISCOVERED = "android.nfc.action.TAG_DISCOVERED"; Loading @@ -78,17 +136,23 @@ public final class NfcAdapter { public static final String ACTION_TAG_LEFT_FIELD = "android.nfc.action.TAG_LOST"; 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"; 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"; 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"; public static final String EXTRA_ID = "android.nfc.extra.ID"; Loading core/java/android/nfc/Tag.java +38 −31 Original line number Original line Diff line number Diff line Loading @@ -38,9 +38,9 @@ import java.util.Arrays; * <p> * <p> * {@link Tag} is an immutable object that represents the state of a NFC tag at * {@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 * 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 * to perform advanced operations, or directly queried for its ID via {@link #getId} and the * set of technologies it contains ({@link #getTechList}). Arrays passed to and * set of technologies it contains via {@link #getTechList}. Arrays passed to and * returned by this class are *not* cloned, so be careful not to modify them. * returned by this class are <em>not</em> cloned, so be careful not to modify them. * <p> * <p> * A new tag object is created every time a tag is discovered (comes into range), even * 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 * if it is the same physical tag. If a tag is removed and then returned into range, then Loading @@ -48,53 +48,60 @@ import java.util.Arrays; * * * <h3>Tag Dispatch</h3> * <h3>Tag Dispatch</h3> * When a tag is discovered, a {@link Tag} object is created and passed to a * 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 * single activity via the {@link NfcAdapter#EXTRA_TAG} extra in an * {@link Context#startActivity} {@link android.content.Intent}. A four stage dispatch is used to select the * {@link android.content.Intent} via {@link Context#startActivity}. A four stage dispatch is used * most appropriate application to handle the tag. The Android OS executes each stage in order, * to select the * and completes dispatch as soon as a single matching application is found. If there are multiple * most appropriate activity to handle the tag. The Android OS executes each stage in order, * matching applications found at any one stage then the Android Activity Chooser dialog is shown * and completes dispatch as soon as a single matching activity is found. If there are multiple * to allow the user to select the application. * 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> * <h4>1. Foreground activity dispatch</h4> * A foreground activity that has called {@link NfcAdapter#enableForegroundDispatch} is * A foreground activity that has called * given priority. See the documentation on {#link NfcAdapter#enableForegroundDispatch} for * {@link NfcAdapter#enableForegroundDispatch NfcAdapter.enableForegroundDispatch()} is * given priority. See the documentation on * {@link NfcAdapter#enableForegroundDispatch NfcAdapter.enableForegroundDispatch()} for * its usage. * its usage. * <h4>2. NDEF data dispatch</h4> * <h4>2. NDEF data dispatch</h4> * If the tag contains NDEF data, then {@link Context#startActivity} is called with * If the tag contains NDEF data the system inspects the first {@link NdefRecord} in the first * {@link NfcAdapter#ACTION_NDEF_DISCOVERED} and a data URI determined from the * {@link NdefMessage}. If the record is a URI, SmartPoster, or MIME data * first NDEF Record in the first NDEF Message in the Tag. This allows NDEF tags to be given * {@link Context#startActivity} is called with {@link NfcAdapter#ACTION_NDEF_DISCOVERED}. For URI * priority dispatch to applications that can handle the content. * 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 * See {@link NfcAdapter#ACTION_NDEF_DISCOVERED} for more detail. If the tag does not contain * NDEF data, or if no application is registered * NDEF data, or if no activity is registered * for {@link NfcAdapter#ACTION_NDEF_DISCOVERED} with a matching data URI then dispatch moves * for {@link NfcAdapter#ACTION_NDEF_DISCOVERED} with a matching data URI or MIME type then dispatch * to stage 3. * moves to stage 3. * <h4>3. Tag Technology dispatch</h4> * <h4>3. Tag Technology dispatch</h4> * {@link Context#startActivity} is called with {@link NfcAdapter#ACTION_TECH_DISCOVERED} to * {@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 * 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 * {@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. * more technologies in the tag. See {@link NfcAdapter#ACTION_TECH_DISCOVERED} for more detail. * <h4>4. Fall-back dispatch</h4> * <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. * {@link NfcAdapter#ACTION_TAG_DISCOVERED}. This is intended as a fall-back mechanism. * See {@link NfcAdapter#ACTION_TAG_DISCOVERED}. * 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> * <h3>NFC Tag Background</h3> * An NFC tag is a passive NFC device, powered by the NFC field of this Android device while * 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. * even embedded in a more sophisticated device. * <p> * <p> * Tags can have a wide range of capabilities. Simple tags just offer read/write semantics, * Tags can have a wide range of capabilities. Simple tags just offer read/write semantics, * and contain some one time * and contain some one time * programmable areas to make read-only. More complex tags offer math operations * programmable areas to make read-only. More complex tags offer math operations * and per-sector access control and authentication. The most sophisticated tags * and per-sector access control and authentication. The most sophisticated tags * contain operating environments such as Javacard, allowing complex interactions with the * contain operating environments allowing complex interactions with the * applets executing on the tag. Use {@link TagTechnology} classes to access a broad * code executing on the tag. Use {@link TagTechnology} classes to access a broad * range of capabilities available in NFC tags. * range of capabilities available in NFC tags. * <p> * <p> */ */ Loading core/java/android/nfc/tech/Ndef.java +0 −1 Original line number Original line Diff line number Diff line Loading @@ -136,7 +136,6 @@ public final class Ndef extends BasicTagTechnology { * @param tag an MIFARE Classic compatible tag * @param tag an MIFARE Classic compatible tag * @return MIFARE Classic object * @return MIFARE Classic object */ */ public static Ndef get(Tag tag) { public static Ndef get(Tag tag) { if (!tag.hasTech(TagTechnology.NDEF)) return null; if (!tag.hasTech(TagTechnology.NDEF)) return null; try { try { Loading Loading
core/java/android/nfc/NfcAdapter.java +79 −15 Original line number Original line Diff line number Diff line Loading @@ -26,8 +26,11 @@ import android.content.Context; import android.content.IntentFilter; import android.content.IntentFilter; import android.content.pm.IPackageManager; import android.content.pm.IPackageManager; import android.content.pm.PackageManager; 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.IBinder; import android.os.Parcel; import android.os.RemoteException; import android.os.RemoteException; import android.os.ServiceManager; import android.os.ServiceManager; import android.util.Log; import android.util.Log; Loading @@ -43,30 +46,85 @@ public final class NfcAdapter { /** /** * Intent to start an activity when a tag with NDEF payload is discovered. * 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. * {@link #ACTION_TECH_DISCOVERED} or {@link #ACTION_TAG_DISCOVERED} will be started. */ */ @SdkConstant(SdkConstantType.ACTIVITY_INTENT_ACTION) @SdkConstant(SdkConstantType.ACTIVITY_INTENT_ACTION) public static final String ACTION_NDEF_DISCOVERED = "android.nfc.action.NDEF_DISCOVERED"; 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 * Intent to start an activity when a tag is discovered and activities are registered for the * {@code vnd.android.nfc://tag/} with the path having a directory entry for each technology * specific technologies on the tag. * in the {@link Tag#getTechList()} is sorted ascending order. * * * <p>To receive this intent an activity must include an intent filter * This intent is started after {@link #ACTION_NDEF_DISCOVERED} and before * for this action and specify the desired tech types in a * {@link #ACTION_TAG_DISCOVERED} * manifest <code>meta-data</code> entry. Here is an example manfiest entry: * * <pre> * If any activities respond to this intent {@link #ACTION_TAG_DISCOVERED} will not be started. * <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". * * <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}: * * <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) @SdkConstant(SdkConstantType.ACTIVITY_INTENT_ACTION) public static final String ACTION_TECH_DISCOVERED = "android.nfc.action.TECH_DISCOVERED"; public static final String ACTION_TECH_DISCOVERED = "android.nfc.action.TECH_DISCOVERED"; /** /** * Intent to start an activity when a tag is 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) @SdkConstant(SdkConstantType.ACTIVITY_INTENT_ACTION) public static final String ACTION_TAG_DISCOVERED = "android.nfc.action.TAG_DISCOVERED"; public static final String ACTION_TAG_DISCOVERED = "android.nfc.action.TAG_DISCOVERED"; Loading @@ -78,17 +136,23 @@ public final class NfcAdapter { public static final String ACTION_TAG_LEFT_FIELD = "android.nfc.action.TAG_LOST"; 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"; 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"; 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"; public static final String EXTRA_ID = "android.nfc.extra.ID"; Loading
core/java/android/nfc/Tag.java +38 −31 Original line number Original line Diff line number Diff line Loading @@ -38,9 +38,9 @@ import java.util.Arrays; * <p> * <p> * {@link Tag} is an immutable object that represents the state of a NFC tag at * {@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 * 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 * to perform advanced operations, or directly queried for its ID via {@link #getId} and the * set of technologies it contains ({@link #getTechList}). Arrays passed to and * set of technologies it contains via {@link #getTechList}. Arrays passed to and * returned by this class are *not* cloned, so be careful not to modify them. * returned by this class are <em>not</em> cloned, so be careful not to modify them. * <p> * <p> * A new tag object is created every time a tag is discovered (comes into range), even * 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 * if it is the same physical tag. If a tag is removed and then returned into range, then Loading @@ -48,53 +48,60 @@ import java.util.Arrays; * * * <h3>Tag Dispatch</h3> * <h3>Tag Dispatch</h3> * When a tag is discovered, a {@link Tag} object is created and passed to a * 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 * single activity via the {@link NfcAdapter#EXTRA_TAG} extra in an * {@link Context#startActivity} {@link android.content.Intent}. A four stage dispatch is used to select the * {@link android.content.Intent} via {@link Context#startActivity}. A four stage dispatch is used * most appropriate application to handle the tag. The Android OS executes each stage in order, * to select the * and completes dispatch as soon as a single matching application is found. If there are multiple * most appropriate activity to handle the tag. The Android OS executes each stage in order, * matching applications found at any one stage then the Android Activity Chooser dialog is shown * and completes dispatch as soon as a single matching activity is found. If there are multiple * to allow the user to select the application. * 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> * <h4>1. Foreground activity dispatch</h4> * A foreground activity that has called {@link NfcAdapter#enableForegroundDispatch} is * A foreground activity that has called * given priority. See the documentation on {#link NfcAdapter#enableForegroundDispatch} for * {@link NfcAdapter#enableForegroundDispatch NfcAdapter.enableForegroundDispatch()} is * given priority. See the documentation on * {@link NfcAdapter#enableForegroundDispatch NfcAdapter.enableForegroundDispatch()} for * its usage. * its usage. * <h4>2. NDEF data dispatch</h4> * <h4>2. NDEF data dispatch</h4> * If the tag contains NDEF data, then {@link Context#startActivity} is called with * If the tag contains NDEF data the system inspects the first {@link NdefRecord} in the first * {@link NfcAdapter#ACTION_NDEF_DISCOVERED} and a data URI determined from the * {@link NdefMessage}. If the record is a URI, SmartPoster, or MIME data * first NDEF Record in the first NDEF Message in the Tag. This allows NDEF tags to be given * {@link Context#startActivity} is called with {@link NfcAdapter#ACTION_NDEF_DISCOVERED}. For URI * priority dispatch to applications that can handle the content. * 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 * See {@link NfcAdapter#ACTION_NDEF_DISCOVERED} for more detail. If the tag does not contain * NDEF data, or if no application is registered * NDEF data, or if no activity is registered * for {@link NfcAdapter#ACTION_NDEF_DISCOVERED} with a matching data URI then dispatch moves * for {@link NfcAdapter#ACTION_NDEF_DISCOVERED} with a matching data URI or MIME type then dispatch * to stage 3. * moves to stage 3. * <h4>3. Tag Technology dispatch</h4> * <h4>3. Tag Technology dispatch</h4> * {@link Context#startActivity} is called with {@link NfcAdapter#ACTION_TECH_DISCOVERED} to * {@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 * 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 * {@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. * more technologies in the tag. See {@link NfcAdapter#ACTION_TECH_DISCOVERED} for more detail. * <h4>4. Fall-back dispatch</h4> * <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. * {@link NfcAdapter#ACTION_TAG_DISCOVERED}. This is intended as a fall-back mechanism. * See {@link NfcAdapter#ACTION_TAG_DISCOVERED}. * 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> * <h3>NFC Tag Background</h3> * An NFC tag is a passive NFC device, powered by the NFC field of this Android device while * 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. * even embedded in a more sophisticated device. * <p> * <p> * Tags can have a wide range of capabilities. Simple tags just offer read/write semantics, * Tags can have a wide range of capabilities. Simple tags just offer read/write semantics, * and contain some one time * and contain some one time * programmable areas to make read-only. More complex tags offer math operations * programmable areas to make read-only. More complex tags offer math operations * and per-sector access control and authentication. The most sophisticated tags * and per-sector access control and authentication. The most sophisticated tags * contain operating environments such as Javacard, allowing complex interactions with the * contain operating environments allowing complex interactions with the * applets executing on the tag. Use {@link TagTechnology} classes to access a broad * code executing on the tag. Use {@link TagTechnology} classes to access a broad * range of capabilities available in NFC tags. * range of capabilities available in NFC tags. * <p> * <p> */ */ Loading
core/java/android/nfc/tech/Ndef.java +0 −1 Original line number Original line Diff line number Diff line Loading @@ -136,7 +136,6 @@ public final class Ndef extends BasicTagTechnology { * @param tag an MIFARE Classic compatible tag * @param tag an MIFARE Classic compatible tag * @return MIFARE Classic object * @return MIFARE Classic object */ */ public static Ndef get(Tag tag) { public static Ndef get(Tag tag) { if (!tag.hasTech(TagTechnology.NDEF)) return null; if (!tag.hasTech(TagTechnology.NDEF)) return null; try { try { Loading
