public final class NdefRecord
extends Object
implements Parcelable
java.lang.Object | |
↳ | android.nfc.NdefRecord |
Represents an immutable NDEF Record.
NDEF (NFC Data Exchange Format) is a light-weight binary format, used to encapsulate typed data. It is specified by the NFC Forum, for transmission and storage with NFC, however it is transport agnostic.
NDEF defines messages and records. An NDEF Record contains typed data, such as MIME-type media, a URI, or a custom application payload. An NDEF Message is a container for one or more NDEF Records.
This class represents logical (complete) NDEF Records, and can not be used to represent chunked (partial) NDEF Records. However NdefMessage(byte[])
can be used to parse a message containing chunked records, and will return a message with unchunked (complete) records.
A logical NDEF Record always contains a 3-bit TNF (Type Name Field) that provides high level typing for the rest of the record. The remaining fields are variable length and not always present:
Helpers such as createUri(Uri)
, createMime(String, byte[])
and createExternal(String, String, byte[])
are included to create well-formatted NDEF Records with correctly set tnf, type, id and payload fields, please use these helpers whenever possible.
Use the constructor NdefRecord(short, byte[], byte[], byte[])
if you know what you are doing and what to set the fields individually. Only basic validation is performed with this constructor, so it is possible to create records that do not confirm to the strict NFC Forum specifications.
The binary representation of an NDEF Record includes additional flags to indicate location with an NDEF message, provide support for chunking of NDEF records, and to pack optional fields. This class does not expose those details. To write an NDEF Record as binary you must first put it into an NdefMessage
, then call toByteArray()
.
NdefMessage
and NdefRecord
implementations are always available, even on Android devices that do not have NFC hardware.
NdefRecord
s are intended to be immutable (and thread-safe), however they may contain mutable fields. So take care not to modify mutable fields passed into constructors, or modify mutable fields obtained by getter methods, unless such modification is explicitly marked as safe.
See also:
Constants |
|
---|---|
short |
TNF_ABSOLUTE_URI Indicates the type field contains an absolute-URI BNF construct defined by RFC 3986. |
short |
TNF_EMPTY Indicates the record is empty. |
short |
TNF_EXTERNAL_TYPE Indicates the type field contains an external type name. |
short |
TNF_MIME_MEDIA Indicates the type field contains a media-type BNF construct, defined by RFC 2046. |
short |
TNF_UNCHANGED Indicates the payload is an intermediate or final chunk of a chunked NDEF Record. |
short |
TNF_UNKNOWN Indicates the payload type is unknown. |
short |
TNF_WELL_KNOWN Indicates the type field contains a well-known RTD type name. |
Inherited constants |
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|
Fields |
|
---|---|
public static final Creator<NdefRecord> |
CREATOR
|
public static final byte[] |
RTD_ALTERNATIVE_CARRIER RTD Alternative Carrier type. |
public static final byte[] |
RTD_HANDOVER_CARRIER RTD Handover Carrier type. |
public static final byte[] |
RTD_HANDOVER_REQUEST RTD Handover Request type. |
public static final byte[] |
RTD_HANDOVER_SELECT RTD Handover Select type. |
public static final byte[] |
RTD_SMART_POSTER RTD Smart Poster type. |
public static final byte[] |
RTD_TEXT RTD Text type. |
public static final byte[] |
RTD_URI RTD URI type. |
Public constructors |
|
---|---|
NdefRecord(short tnf, byte[] type, byte[] id, byte[] payload) Construct an NDEF Record from its component fields. |
|
NdefRecord(byte[] data) This constructor was deprecated in API level 16. use |
Public methods |
|
---|---|
static NdefRecord |
createApplicationRecord(String packageName) Create a new Android Application Record (AAR). |
static NdefRecord |
createExternal(String domain, String type, byte[] data) Create a new NDEF Record containing external (application-specific) data. |
static NdefRecord |
createMime(String mimeType, byte[] mimeData) Create a new NDEF Record containing MIME data. |
static NdefRecord |
createTextRecord(String languageCode, String text) Create a new NDEF record containing UTF-8 text data. |
static NdefRecord |
createUri(Uri uri) Create a new NDEF Record containing a URI. |
static NdefRecord |
createUri(String uriString) Create a new NDEF Record containing a URI. |
int |
describeContents() Describe the kinds of special objects contained in this Parcelable instance's marshaled representation. |
boolean |
equals(Object obj) Returns true if the specified NDEF Record contains identical tnf, type, id and payload fields. |
byte[] |
getId() Returns the variable length ID. |
byte[] |
getPayload() Returns the variable length payload. |
short |
getTnf() Returns the 3-bit TNF. |
byte[] |
getType() Returns the variable length Type field. |
int |
hashCode() Returns a hash code value for the object. |
byte[] |
toByteArray() This method was deprecated in API level 16. use |
String |
toMimeType() Map this record to a MIME type, or return null if it cannot be mapped. |
String |
toString() Returns a string representation of the object. |
Uri |
toUri() Map this record to a URI, or return null if it cannot be mapped. |
void |
writeToParcel(Parcel dest, int flags) Flatten this object in to a Parcel. |
Inherited methods |
|
---|---|
![]() java.lang.Object
|
|
![]() android.os.Parcelable
|
short TNF_ABSOLUTE_URI
Indicates the type field contains an absolute-URI BNF construct defined by RFC 3986.
When creating new records prefer createUri(Uri)
, since it offers more compact URI encoding (#RTD_URI allows compression of common URI prefixes).
See also:
Constant Value: 3 (0x00000003)
short TNF_EMPTY
Indicates the record is empty.
Type, id and payload fields are empty in a TNF_EMPTY record.
Constant Value: 0 (0x00000000)
short TNF_EXTERNAL_TYPE
Indicates the type field contains an external type name.
Used to encode custom payloads. When creating new records use the helper createExternal(String, String, byte[])
.
The external-type RTD format is specified in NFCForum-TS-RTD_1.0.
Note this TNF should not be used with RTD_TEXT or RTD_URI constants. Those are well known RTD constants, not external RTD constants.
See also:
Constant Value: 4 (0x00000004)
short TNF_MIME_MEDIA
Indicates the type field contains a media-type BNF construct, defined by RFC 2046.
Use this with MIME type names such as "image/jpeg", or using the helper createMime(String, byte[])
.
See also:
Constant Value: 2 (0x00000002)
short TNF_UNCHANGED
Indicates the payload is an intermediate or final chunk of a chunked NDEF Record.
TNF_UNCHANGED can not be used with this class since all NdefRecord
s are already unchunked, however they may appear in the binary format.
Constant Value: 6 (0x00000006)
short TNF_UNKNOWN
Indicates the payload type is unknown.
NFC Forum explains this should be treated similarly to the "application/octet-stream" MIME type. The payload type is not explicitly encoded within the record.
The type field is empty in an TNF_UNKNOWN record.
Constant Value: 5 (0x00000005)
short TNF_WELL_KNOWN
Indicates the type field contains a well-known RTD type name.
Use this tnf with RTD types such as RTD_TEXT
, RTD_URI
.
The RTD type name format is specified in NFCForum-TS-RTD_1.0.
See also:
Constant Value: 1 (0x00000001)
byte[] RTD_ALTERNATIVE_CARRIER
RTD Alternative Carrier type. For use with TNF_WELL_KNOWN.
See also:
byte[] RTD_HANDOVER_CARRIER
RTD Handover Carrier type. For use with TNF_WELL_KNOWN.
See also:
byte[] RTD_HANDOVER_REQUEST
RTD Handover Request type. For use with TNF_WELL_KNOWN.
See also:
byte[] RTD_HANDOVER_SELECT
RTD Handover Select type. For use with TNF_WELL_KNOWN.
See also:
byte[] RTD_SMART_POSTER
RTD Smart Poster type. For use with TNF_WELL_KNOWN.
See also:
NdefRecord (short tnf, byte[] type, byte[] id, byte[] payload)
Construct an NDEF Record from its component fields.
Recommend to use helpers such as {#createUri} or {createExternal(String, String, byte[])
where possible, since they perform stricter validation that the record is correctly formatted as per NDEF specifications. However if you know what you are doing then this constructor offers the most flexibility.
An NdefRecord
represents a logical (complete) record, and cannot represent NDEF Record chunks.
Basic validation of the tnf, type, id and payload is performed as per the following rules:
TNF_EMPTY
cannot have a type, id or payload.TNF_UNKNOWN
or 0x07 cannot have a type.TNF_UNCHANGED
are not allowed since this class only represents complete (unchunked) records. If any of the above validation steps fail then IllegalArgumentException
is thrown.
Deep inspection of the type, id and payload fields is not performed, so it is possible to create NDEF Records that conform to section 3.2.6 but fail other more strict NDEF specification requirements. For example, the payload may be invalid given the tnf and type.
To omit a type, id or payload field, set the parameter to an empty byte array or null.
Parameters | |
---|---|
tnf |
short : a 3-bit TNF constant |
type |
byte : byte array, containing zero to 255 bytes, or null |
id |
byte : byte array, containing zero to 255 bytes, or null |
payload |
byte : byte array, containing zero to (2 ** 32 - 1) bytes, or null |
Throws | |
---|---|
|
if a valid record cannot be created |
NdefRecord (byte[] data)
This constructor was deprecated in API level 16.
use NdefMessage(byte[])
instead.
Construct an NDEF Record from raw bytes.
This method is deprecated, use NdefMessage(byte[])
instead. This is because it does not make sense to parse a record: the NDEF binary format is only defined for a message, and the record flags MB and ME do not make sense outside of the context of an entire message.
This implementation will attempt to parse a single record by ignoring the MB and ME flags, and otherwise following the rules of NdefMessage(byte[])
.
Parameters | |
---|---|
data |
byte : raw bytes to parse |
Throws | |
---|---|
FormatException |
if the data cannot be parsed into a valid record |
NdefRecord createApplicationRecord (String packageName)
Create a new Android Application Record (AAR).
This record indicates to other Android devices the package that should be used to handle the entire NDEF message. You can embed this record anywhere into your message to ensure that the intended package receives the message.
When an Android device dispatches an NdefMessage
containing one or more Android application records, the applications contained in those records will be the preferred target for the ACTION_NDEF_DISCOVERED
intent, in the order in which they appear in the message. This dispatch behavior was first added to Android in Ice Cream Sandwich.
If none of the applications have a are installed on the device, a Market link will be opened to the first application.
Note that Android application records do not overrule applications that have called enableForegroundDispatch(Activity, PendingIntent, IntentFilter[], String[][])
.
Parameters | |
---|---|
packageName |
String : Android package name |
Returns | |
---|---|
NdefRecord |
Android application NDEF record |
NdefRecord createExternal (String domain, String type, byte[] data)
Create a new NDEF Record containing external (application-specific) data.
Use this method to encode application specific data into an NDEF Record. The data is typed by a domain name (usually your Android package name) and a domain-specific type. This data is packaged into a "NFC Forum External Type" NDEF Record.
NFC Forum requires that the domain and type used in an external record are treated as case insensitive, however Android intent filtering is always case sensitive. So this method will force the domain and type to lower-case before creating the NDEF Record.
The unchecked exception IllegalArgumentException
will be thrown if the domain and type have serious problems, for example if either field is empty, so always catch this exception if you are passing user-generated data into this method.
There are no such restrictions on the payload data.
For efficiency, This method might not make an internal copy of the data byte array, so take care not to modify the data byte array while still using the returned NdefRecord. Reference specification: NFCForum-TS-RTD_1.0
Parameters | |
---|---|
domain |
String : domain-name of issuing organization |
type |
String : domain-specific type of data |
data |
byte : payload as bytes |
Returns | |
---|---|
NdefRecord |
Throws | |
---|---|
|
if either domain or type are empty or invalid |
NdefRecord createMime (String mimeType, byte[] mimeData)
Create a new NDEF Record containing MIME data.
Use this method to encode MIME-typed data into an NDEF Record, such as "text/plain", or "image/jpeg".
The mimeType parameter will be normalized with normalizeMimeType(String)
to follow Android best practices for intent filtering, for example to force lower-case. However the unchecked exception IllegalArgumentException
may be thrown if the mimeType parameter has serious problems, for example if it is empty, so always catch this exception if you are passing user-generated data into this method.
For efficiency, This method might not make an internal copy of the mimeData byte array, so take care not to modify the mimeData byte array while still using the returned NdefRecord.
Parameters | |
---|---|
mimeType |
String : a valid MIME type |
mimeData |
byte : MIME data as bytes |
Returns | |
---|---|
NdefRecord |
an NDEF Record containing the MIME-typed data |
Throws | |
---|---|
|
if the mimeType is empty or invalid |
NdefRecord createTextRecord (String languageCode, String text)
Create a new NDEF record containing UTF-8 text data.
The caller can either specify the language code for the provided text, or otherwise the language code corresponding to the current default locale will be used. Reference specification: NFCForum-TS-RTD_Text_1.0
Parameters | |
---|---|
languageCode |
String : The languageCode for the record. If locale is empty or null, the language code of the current default locale will be used. |
text |
String : The text to be encoded in the record. Will be represented in UTF-8 format. |
Returns | |
---|---|
NdefRecord |
Throws | |
---|---|
IllegalArgumentException |
if text is null |
NdefRecord createUri (Uri uri)
Create a new NDEF Record containing a URI.
Use this method to encode a URI (or URL) into an NDEF Record.
Uses the well known URI type representation: TNF_WELL_KNOWN
and RTD_URI
. This is the most efficient encoding of a URI into NDEF.
The uri parameter will be normalized with normalizeScheme()
to set the scheme to lower case to follow Android best practices for intent filtering. However the unchecked exception IllegalArgumentException
may be thrown if the uri parameter has serious problems, for example if it is empty, so always catch this exception if you are passing user-generated data into this method.
Reference specification: NFCForum-TS-RTD_URI_1.0
Parameters | |
---|---|
uri |
Uri : URI to encode. |
Returns | |
---|---|
NdefRecord |
an NDEF Record containing the URI |
Throws | |
---|---|
|
if the uri is empty or invalid |
NdefRecord createUri (String uriString)
Create a new NDEF Record containing a URI.
Use this method to encode a URI (or URL) into an NDEF Record.
Uses the well known URI type representation: TNF_WELL_KNOWN
and RTD_URI
. This is the most efficient encoding of a URI into NDEF.
The uriString parameter will be normalized with normalizeScheme()
to set the scheme to lower case to follow Android best practices for intent filtering. However the unchecked exception IllegalArgumentException
may be thrown if the uriString parameter has serious problems, for example if it is empty, so always catch this exception if you are passing user-generated data into this method.
Reference specification: NFCForum-TS-RTD_URI_1.0
Parameters | |
---|---|
uriString |
String : string URI to encode. |
Returns | |
---|---|
NdefRecord |
an NDEF Record containing the URI |
Throws | |
---|---|
|
if the uriString is empty or invalid |
int describeContents ()
Describe the kinds of special objects contained in this Parcelable instance's marshaled representation. For example, if the object will include a file descriptor in the output of writeToParcel(Parcel, int)
, the return value of this method must include the CONTENTS_FILE_DESCRIPTOR
bit.
Returns | |
---|---|
int |
a bitmask indicating the set of special object types marshaled by this Parcelable object instance. |
boolean equals (Object obj)
Returns true if the specified NDEF Record contains identical tnf, type, id and payload fields.
Parameters | |
---|---|
obj |
Object : the reference object with which to compare. |
Returns | |
---|---|
boolean |
true if this object is the same as the obj argument; false otherwise. |
byte[] getId ()
Returns the variable length ID.
Returns an empty byte array if this record does not have an id field.
Returns | |
---|---|
byte[] |
byte[] getPayload ()
Returns the variable length payload.
Returns an empty byte array if this record does not have a payload field.
Returns | |
---|---|
byte[] |
short getTnf ()
Returns the 3-bit TNF.
TNF is the top-level type.
Returns | |
---|---|
short |
byte[] getType ()
Returns the variable length Type field.
This should be used in conjunction with the TNF field to determine the payload format.
Returns an empty byte array if this record does not have a type field.
Returns | |
---|---|
byte[] |
int hashCode ()
Returns a hash code value for the object. This method is supported for the benefit of hash tables such as those provided by HashMap
.
The general contract of hashCode
is:
hashCode
method must consistently return the same integer, provided no information used in equals
comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application. equals(Object)
method, then calling the hashCode
method on each of the two objects must produce the same integer result. equals(java.lang.Object)
method, then calling the hashCode
method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hash tables. As much as is reasonably practical, the hashCode method defined by class Object
does return distinct integers for distinct objects. (This is typically implemented by converting the internal address of the object into an integer, but this implementation technique is not required by the JavaTM programming language.)
Returns | |
---|---|
int |
a hash code value for this object. |
byte[] toByteArray ()
This method was deprecated in API level 16.
use toByteArray()
instead
Return this NDEF Record as a byte array.
This method is deprecated, use toByteArray()
instead. This is because the NDEF binary format is not defined for a record outside of the context of a message: the MB and ME flags cannot be set without knowing the location inside a message.
This implementation will attempt to serialize a single record by always setting the MB and ME flags (in other words, assume this is a single-record NDEF Message).
Returns | |
---|---|
byte[] |
String toMimeType ()
Map this record to a MIME type, or return null if it cannot be mapped.
Currently this method considers all TNF_MIME_MEDIA
records to be MIME records, as well as some TNF_WELL_KNOWN
records such as RTD_TEXT
. If this is a MIME record then the MIME type as string is returned, otherwise null is returned.
This method does not perform validation that the MIME type is actually valid. It always attempts to return a string containing the type if this is a MIME record.
The returned MIME type will by normalized to lower-case using normalizeMimeType(String)
.
The MIME payload can be obtained using getPayload()
.
Returns | |
---|---|
String |
MIME type as a string, or null if this is not a MIME record |
String toString ()
Returns a string representation of the object. In general, the toString
method returns a string that "textually represents" this object. The result should be a concise but informative representation that is easy for a person to read. It is recommended that all subclasses override this method.
The toString
method for class Object
returns a string consisting of the name of the class of which the object is an instance, the at-sign character `@
', and the unsigned hexadecimal representation of the hash code of the object. In other words, this method returns a string equal to the value of:
getClass().getName() + '@' + Integer.toHexString(hashCode())
Returns | |
---|---|
String |
a string representation of the object. |
Uri toUri ()
Map this record to a URI, or return null if it cannot be mapped.
Currently this method considers the following to be URI records:
TNF_ABSOLUTE_URI
records.TNF_WELL_KNOWN
with a type of RTD_URI
.TNF_WELL_KNOWN
with a type of RTD_SMART_POSTER
and containing a URI record in the NDEF message nested in the payload. TNF_EXTERNAL_TYPE
records.This method does not perform validation that the URI is actually valid: it always attempts to create and return a URI if this record appears to be a URI record by the above rules.
The returned URI will be normalized to have a lower case scheme using normalizeScheme()
.
Returns | |
---|---|
Uri |
URI, or null if this is not a URI record |
void writeToParcel (Parcel dest, int flags)
Flatten this object in to a Parcel.
Parameters | |
---|---|
dest |
Parcel : The Parcel in which the object should be written. |
flags |
int : Additional flags about how the object should be written. May be 0 or PARCELABLE_WRITE_RETURN_VALUE . |