Read/write in Ndef format in android nfc

Process in Activity after detecting tags

1. Obtain the NfcAdapter object in onCreate;

NfcAdapter nfcAdapter = NfcAdapter. getdefaadapter adapter (this );

2. Obtain the Tag object or NdefMessage information in onNewIntent;

Get Tag object:

Tag tag = intent. getParcelableExra (NfcAdapter. EXTRA_TAG );

Obtain NdefMessage:

Parcelable [] rawMsgs = getIntent (). getParcelableArrayExtra (NfcAdapter. EXTRA_NDEF_MESSAGES)

3. You can also create Ndef objects using tags to implement Tag attributes and I/O operations.

Ndef ndef = Ndef. get (tag );

NDEF format label reading process

1. Obtain the NfcAdapter object in onCreate;

2. In onNewIntent (), determine whether the tag is in the NDEF format (ACTION_NDEF_DISCOVERED). If yes, obtain the NdefMessage

Information; (forced conversion to NdefMessage object)

Parcelable [] rawMsgs = getIntent (). getParcelableArrayExtra (NfcAdapter. EXTRA_NDEF_MESSAGES)

3. parse the NdefMessage object to obtain the relevant text information or Uri.

NDEF format label Writing Process

1. Obtain the NfcAdapter object in onCreate;

2. Get the Tag object in onNewIntent;

Tag tag = intent. getParcelableExra (NfcAdapter. EXTRA_TAG );

3. Create an Ndef object using tags;

Ndef ndef = Ndef. get (tag );

4. encapsulate text and other data into NdefMessage;

5. Determine whether the tag is in NDEF format,

If the format is NDEF:

(1) Allow tag operations: ndef. connect ();

(2) Call ndef. writeNdefMessage (NdefMessage) to write data.

If the format is not NDEF:

(1) NdefFromatable format = NdefFromatable. get ();

(2) allow tag operations: format. connect ();

(3) Call format. format (NdefMessage) to write data.

NdefMessage Structure

NdefRecZ records? Http://www.bkjia.com/kf/ware/vc/ "target =" _ blank "class =" keylink "> cipher + c1_vcd4kpha + MS6/cipher + c1_vcd4kpha + PGJyPgo8L3A + cipher + PGJyPgo8L3A + cipher + zcrHyrW8yrXEyv2 + 3aOsxuTW0E5ERUbOxLG + JiMyNjY4NDvKvc6qo7o8YnI + ch7vcd4kpha + pgltzybzcm9 "http://www.2cto.com/uploadfile/Collfiles/20140430/20140430090648250.png" alt = "\">

NDEF Uri format

1. paylaod in NdefMessage is the actual data. The NDEF text format is:

2. The prefix must be parsed using the lookup table.

Example program:

ReadWriteTextMainActivity:

Package mobile. android. read. write. text; import java. nio. charset. charset; import java. util. locale; import android. app. activity; import android. content. intent; import android. nfc. ndefMessage; import android. nfc. ndefRecord; import android. nfc. nfcAdapter; import android. nfc. tag; import android. nfc. tech. ndef; import android. nfc. tech. ndefFormatable; import android. OS. bundle; import android. view. view; import android. w Idget. textView; import android. widget. toast; public class ReadWriteTextMainActivity extends Activity {private TextView mInputText; private String mText; @ Override public void onCreate (Bundle savedInstanceState) {super. onCreate (savedInstanceState); setContentView (R. layout. activity_read_write_text_main); mInputText = (TextView) findViewById (R. id. textview_input_text);} // click the public vo method executed by the "Enter Text to write" button. Id onClick_InputText (View view) {Intent intent = new Intent (this, InputTextActivity. class); // startActivityForResult (intent, 1);} @ Override protected void onActivityResult (int requestCode, int resultCode, Intent data) {if (requestCode = 1 & resultCode = 1) {// obtain the text mText = data to write tags. getStringExtra ("text"); // The mInputText to be written to the tag is displayed on the main interface. setText (mText) ;}}// when the window creation mode is singleTop or single Task call, used to replace the onCreate method // when the NFC tag is near the mobile phone, call @ Override public void onNewIntent (Intent intent) after the connection is established {// if the text to be written is not set, if (mText = null) {Intent myIntent = new Intent (this, ShowNFCTagContentActivity. class); // pass intent to another window to display the interface window myIntent. putExtras (intent); // you need to specify this Action. When an Intent object is passed, the Action will not pass myIntent. setAction (NfcAdapter. ACTION_NDEF_DISCOVERED); startActivity (myIntent);} // write the specified text to the NFC tag e Lse {// get Tag OBJECT Tag = intent. getParcelableExtra (NfcAdapter. EXTRA_TAG); // create NdefMessage object and NdefRecord object NdefMessage ndefMessage = new NdefMessage (new NdefRecord [] {createTextRecord (mText )}); // start to write text to the label if (writeTag (ndefMessage, tag) {// if the text is successfully written, set mtext to null mText = null; // clear the text to be written in the main window. The text can only be written once. // to continue writing, specify the new text again. Otherwise, only the text mInputText in the label will be read. setText ("") ;}}// create an NdefRecord object publ that encapsulates the text to be written Ic NdefRecord createTextRecord (String text) {// a byte array generated for language encoding. The byte is encoded in Chinese [] langBytes = Locale. CHINA. getLanguage (). getBytes (Charset. forName ("US-ASCII"); // encode the text to be written in UTF_8 format Charset utfEncoding = Charset. forName ("UTF-8"); // Since the format of the determined text is encoded as UTF_8, the 1st bits of the payload 7th bytes are directly set to 0 byte [] textBytes = text. getBytes (utfEncoding); int utfBit = 0; // define and initialize the status byte char status = (char) (utfBit + langBytes. length); // create a storage Byte [] data = new byte [1 + langBytes. length + textBytes. length]; // sets the status byte data [0] = (byte) status; // sets the language encoding System. arraycopy (langBytes, 0, data, 1, langBytes. length); // set the actual text to be written to System. arraycopy (textBytes, 0, data, 1 + langBytes. length, textBytes. length); // create the NdefRecord object NdefRecord record = new NdefRecord (NdefRecord. TNF_WELL_KNOWN, NdefRecord. RTD_TEXT, new byte [0], d Ata); return record;} // write the NdefMessage object to a Tag. If the tag is successfully written, true is returned. Otherwise, false boolean writeTag (NdefMessage message, Tag tag) {int size = message is returned. toByteArray (). length; try {// obtain Ndef object Ndef ndef = Ndef. get (tag); if (ndef! = Null) {// allow I/O operations on tags ndef. connect (); if (! Ndef. isWritable () {Toast. makeText (this, "NFC Tag is read-only! ", Toast. LENGTH_LONG). show (); return false;} if (ndef. getMaxSize () <size) {Toast. makeText (this," NFC Tag space is insufficient! ", Toast. LENGTH_LONG). show (); return false;} // write data to the tag ndef. writeNdefMessage (message); Toast. makeText (this," data has been written successfully! ", Toast. LENGTH_LONG ). show (); return true;} else {// get the NdefFormatable object NdefFormatable that can format and write data to tags. format = NdefFormatable. get (tag); // write NDEF data if (format! = Null) {try {// allow I/O operations on tags format. connect (); format. format (message); Toast. makeText (this, "data has been written successfully! ", Toast. LENGTH_LONG). show (); return true;} catch (Exception e) {Toast. makeText (this," failed to write data in NDEF format! ", Toast. LENGTH_LONG). show (); return false ;}} else {Toast. makeText (this," NFC tags do not support NDEF format! ", Toast. LENGTH_LONG ). show (); return false ;}} catch (Exception e) {Toast. makeText (this, e. getMessage (), Toast. LENGTH_LONG ). show (); return false ;}}}

InputTextActivity:

package mobile.android.read.write.text;import android.app.Activity;import android.content.Intent;import android.os.Bundle;import android.view.View;import android.widget.EditText;public class InputTextActivity extends Activity {    private EditText mTextTag;    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_input_text);        mTextTag = (EditText) findViewById(R.id.edittext_text_tag);    }    public void onClick_OK(View view) {        Intent intent = new Intent();        intent.putExtra("text", mTextTag.getText().toString());        setResult(1, intent);        finish();    }}

ShowNFCTagContentActivity:

Package mobile. android. read. write. text; import mobile. android. read. write. text. library. textRecord; import android. app. activity; import android. content. intent; import android. nfc. ndefMessage; import android. nfc. ndefRecord; import android. nfc. nfcAdapter; import android. nfc. tag; import android. nfc. tech. ndef; import android. OS. bundle; import android. OS. parcelable; import android. widget. textView; import android. widg Et. toast; public class ShowNFCTagContentActivity extends Activity {private TextView mTagContent; private Tag mDetectedTag; private String mTagText; private void readAndShowData (Intent intent) {mDetectedTag = intent. getParcelableExtra (NfcAdapter. EXTRA_TAG); Ndef ndef = Ndef. get (mDetectedTag); mTagText = ndef. getType () + "\ n maximum data capacity:" + ndef. getMaxSize () + "bytes \ n"; readNFCTag (); mTagContent. setT Ext (mTagText) ;}@ Override public void onCreate (Bundle savedInstanceState) {super. onCreate (savedInstanceState); setContentView (R. layout. activity_show_nfctag_content); mTagContent = (TextView) findViewById (R. id. textview_tag_content); // obtain the Tag object mDetectedTag = getIntent (). getParcelableExtra (NfcAdapter. EXTRA_TAG); // create Ndef object Ndef ndef = Ndef. get (mDetectedTag); // obtain the tag type and maximum capacity mTagText = ndef. getType () + "\ N maximum data capacity:" + ndef. getMaxSize () + "bytes \ n"; // read NFC tag data and parse readNFCTag (); // display tag-related information on the mTagContent page. setText (mTagText);} private void readNFCTag () {// determine whether it is ACTION_NDEF_DISCOVERED if (NfcAdapter. ACTION_NDEF_DISCOVERED.equals (getIntent (). getAction () {// read data from tags (Parcelable object) Parcelable [] rawMsgs = getIntent (). getParcelableArrayExtra (NfcAdapter. EXTRA_NDEF_MESSAGES); NdefMessage msgs [] = Null; int contentSize = 0; if (rawMsgs! = Null) {msgs = new NdefMessage [rawMsgs. length]; // The tag may store multiple NdefMessage objects. Generally, there is only one NdefMessage object for (int I = 0; I <rawMsgs. length; I ++) {// converts it to the NdefMessage object msgs [I] = (NdefMessage) rawMsgs [I]; // calculate the total length of the Data contentSize + = msgs [I]. toByteArray (). length ;}} try {if (msgs! = Null) {// only one NdefRecord object is taken into account in the program. For general purpose software, all NdefRecord objects NdefRecord record = msgs [0] should be considered. getRecords () [0]; // analyze 1st NdefRecorder and create the TextRecord object TextRecord textRecord = TextRecord. parse (msgs [0]. getRecords () [0]); // obtain the actual data usage and display mTagText + = textRecord in the window. getText () + "\ n plain text \ n" + contentSize + "bytes" ;}} catch (Exception e) {mTagContent. setText (e. getMessage ());}}}}

TextRecord:

Package mobile. android. read. write. text. library; import java. io. unsupportedEncodingException; import java. util. arrays; import android. nfc. ndefRecord; public class TextRecord {// stores the parsed text private final String mText; // The TextRecord object cannot be created directly, so the constructor is declared as private TextRecord (String text) {mText = text;} // This method can be used to obtain the parsed public String getText () {return mText;} // extract plain text content from the NdefRecord object (payload) parsing pu Blic static TextRecord parse (NdefRecord record) {// verify whether the TNF is NdefRecord. TNF_WELL_KNOWN if (record. getTnf ()! = NdefRecord. TNF_WELL_KNOWN) return null; // verify whether the variable length type is RTD_TEXT if (! Arrays. equals (record. getType (), NdefRecord. RTD_TEXT) return null; try {// get payload byte [] payload = record. getPayload (); // the following code analyzes payload: Status byte + ISO language encoding (ASCLL) + text data (UTF_8/UTF_16) // The payload [0] placement status byte: if bit7 is 0, text data is encoded in UTF_8 format. If it is 1, it is reserved in UTF_16 encoding // bit6, the default value is 0/** payload [0] contains the "Status Byte Encodings" field, per the * NFC Forum "Text Record Type Definition" section 3.2.1. ** bit7 is the Text E Ncoding Field. ** if (Bit_7 = 0): The text is encoded in UTF-8 if (Bit_7 = 1 ): * The text is encoded in UTF16 ** Bit_6 is reserved for future use and must be set to zero. ** Bits 5 to 0 are the length of the IANA language code. */String textEncoding = (payload [0] & 0x80) = 0 )? "UTF-8": "UTF-16"; // processing bit5-0. Bit5-0 represents the language encoding length (bytes) int bytes agecodelength = payload [0] & 0x3f; // gets the language encoding (reads languageCodeLength bytes from the 2nd bytes of payload as the language encoding) string languageCode = new String (payload, 1, languageCodeLength, "US-ASCII"); // parse the actual text data String text = new String (payload, languageCodeLength + 1, payload. length-shortagecodelength-1, textEncoding); // create a TextRecord object and return the return new TextRecord (text);} catch (UnsupportedEncodingException e) {// shocould never happen unless we get a malformed tag. throw new IllegalArgumentException (e );}}}

AndroidManifest. xml: