Skip to content

Most visited

Recently visited

navigation

HostNfcFService

public abstract class HostNfcFService
extends Service

java.lang.Object
   ↳ android.content.Context
     ↳ android.content.ContextWrapper
       ↳ android.app.Service
         ↳ android.nfc.cardemulation.HostNfcFService


HostNfcFService is a convenience Service class that can be extended to emulate an NFC-F card inside an Android service component.

NFC Protocols

Cards emulated by this class are based on the NFC-Forum NFC-F protocol (based on the JIS-X 6319-4 specification.)

System Code and NFCID2 registration

A HostNfcFService service can register exactly one System Code and one NFCID2. For details about the use of System Code and NFCID2, see the NFC Forum Digital specification.

To statically register a System Code and NFCID2 with the service, a SERVICE_META_DATA entry must be included in the declaration of the service.

All HostNfcFService declarations in the manifest must require the BIND_NFC_SERVICE permission in their <service> tag, to ensure that only the platform can bind to your service.

An example of a HostNfcFService manifest declaration is shown below:

 <service android:name=".MyHostNfcFService" android:exported="true" android:permission="android.permission.BIND_NFC_SERVICE">
     <intent-filter>
         <action android:name="android.nfc.cardemulation.action.HOST_NFCF_SERVICE"/>
     </intent-filter>
     <meta-data android:name="android.nfc.cardemulation.host_nfcf_service" android:resource="@xml/nfcfservice"/>
 </service>
This meta-data tag points to an nfcfservice.xml file. An example of this file with a System Code and NFCID2 declaration is shown below:
 <host-nfcf-service xmlns:android="http://schemas.android.com/apk/res/android"
           android:description="@string/servicedesc">
       <system-code-filter android:name="4000"/>
       <nfcid2-filter android:name="02FE000000000000"/>
 </host-nfcf-service>
 

The <host-nfcf-service> is required to contain a <android:description> attribute that contains a user-friendly description of the service that may be shown in UI.

The <host-nfcf-service> must contain:

Alternatively, the System Code and NFCID2 can be dynamically registererd for a service by using the registerSystemCodeForService(ComponentName, String) and setNfcid2ForService(ComponentName, String) methods.

Service selection

When a remote NFC devices wants to communicate with your service, it sends a SENSF_REQ command to the NFC controller, requesting a System Code. If a NfcFCardEmulation service has registered this system code and has been enabled by the foreground application, the NFC controller will respond with the NFCID2 that is registered for this service. The reader can then continue data exchange with this service by using the NFCID2.

Data exchange

After service selection, all frames addressed to the NFCID2 of this service will be sent through processNfcFPacket(byte[], Bundle), until the NFC link is broken.

When the NFC link is broken, onDeactivated(int) will be called.

Summary

Constants

int DEACTIVATION_LINK_LOSS

Reason for onDeactivated(int).

String SERVICE_INTERFACE

The Intent action that must be declared as handled by the service.

String SERVICE_META_DATA

The name of the meta-data element that contains more information about this service.

Inherited constants

From class android.app.Service
From class android.content.Context
From interface android.content.ComponentCallbacks2

Public constructors

HostNfcFService()

Public methods

final IBinder onBind(Intent intent)

Return the communication channel to the service.

abstract void onDeactivated(int reason)

This method will be called in following possible scenarios:

  • The NFC link has been lost

  • abstract byte[] processNfcFPacket(byte[] commandPacket, Bundle extras)

    This method will be called when a NFC-F packet has been received from a remote device.

    final void sendResponsePacket(byte[] responsePacket)

    Sends a response packet back to the remote device.

    Inherited methods

    From class android.app.Service
    From class android.content.ContextWrapper
    From class android.content.Context
    From class java.lang.Object
    From interface android.content.ComponentCallbacks2
    From interface android.content.ComponentCallbacks

    Constants

    DEACTIVATION_LINK_LOSS

    added in API level 24
    int DEACTIVATION_LINK_LOSS

    Reason for onDeactivated(int). Indicates deactivation was due to the NFC link being lost.

    Constant Value: 0 (0x00000000)

    SERVICE_INTERFACE

    added in API level 24
    String SERVICE_INTERFACE

    The Intent action that must be declared as handled by the service.

    Constant Value: "android.nfc.cardemulation.action.HOST_NFCF_SERVICE"

    SERVICE_META_DATA

    added in API level 24
    String SERVICE_META_DATA

    The name of the meta-data element that contains more information about this service.

    Constant Value: "android.nfc.cardemulation.host_nfcf_service"

    Public constructors

    HostNfcFService

    added in API level 24
    HostNfcFService ()

    Public methods

    onBind

    added in API level 24
    IBinder onBind (Intent intent)

    Return the communication channel to the service. May return null if clients can not bind to the service. The returned IBinder is usually for a complex interface that has been described using aidl.

    Note that unlike other application components, calls on to the IBinder interface returned here may not happen on the main thread of the process. More information about the main thread can be found in Processes and Threads.

    Parameters
    intent Intent: The Intent that was used to bind to this service, as given to Context.bindService. Note that any extras that were included with the Intent at that point will not be seen here.
    Returns
    IBinder Return an IBinder through which clients can call on to the service.

    onDeactivated

    added in API level 24
    void onDeactivated (int reason)

    This method will be called in following possible scenarios:

  • The NFC link has been lost

    Parameters
    reason int: DEACTIVATION_LINK_LOSS
  • processNfcFPacket

    added in API level 24
    byte[] processNfcFPacket (byte[] commandPacket, 
                    Bundle extras)

    This method will be called when a NFC-F packet has been received from a remote device. A response packet can be provided directly by returning a byte-array in this method. Note that in general response packets must be sent as quickly as possible, given the fact that the user is likely holding his device over an NFC reader when this method is called.

    This method is running on the main thread of your application. If you cannot return a response packet immediately, return null and use the sendResponsePacket(byte[]) method later.

    Parameters
    commandPacket byte: The NFC-F packet that was received from the remote device
    extras Bundle: A bundle containing extra data. May be null.
    Returns
    byte[] a byte-array containing the response packet, or null if no response packet can be sent at this point.

    sendResponsePacket

    added in API level 24
    void sendResponsePacket (byte[] responsePacket)

    Sends a response packet back to the remote device.

    Note: this method may be called from any thread and will not block.

    Parameters
    responsePacket byte: A byte-array containing the response packet.
    This site uses cookies to store your preferences for site-specific language and display options.

    Hooray!

    This class requires API level or higher

    This doc is hidden because your selected API level for the documentation is . You can change the documentation API level with the selector above the left navigation.

    For more information about specifying the API level your app requires, read Supporting Different Platform Versions.

    Take a one-minute survey?
    Help us improve Android tools and documentation.