NFC技术的基础应用
2016-01-18 16:00
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There are two major uses cases when working with NDEF data and Android:
1、Reading NDEF data from an NFC tag
2、Beaming NDEF messages from one device to another with Android Beam™。
在安卓系统的应用中，最主要的有两种应用场景，第一个就是读取NEC标签里面的NDEF格式的数据，第二个就是不同设备间的NDEF信息数据的操作。接下来就主要学习一下这两块的实际应用。
首先学习一下基础知识：
一、权限的声明：
<uses-permission android:name="android.permission.NFC" />
private NfcAdapter nfcAdapter;
private PendingIntent pendingIntent;
private IntentFilter[] filters;
private String[][] techLists=null;
所谓前台调度就是指我们直接在一个当前运行程序的Activity中显式的应用NFC；而标签调度就是指我们在我们的应用程序中配置好相关的Intent-filter,当设备接触到NFC标签的时候会调用有该配置的应用程序。
前台调度方式：（Manifest文件下的配置不做任何调整，只是声明一个普通的Activity即可）
public class MainActivity extends AppCompatActivity implements NfcAdapter.CreateNdefMessageCallback{
private NfcAdapter nfcAdapter;
private PendingIntent pendingIntent;
private IntentFilter[] filters;
private String[][] techLists=null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
checkNdef();
}
private void checkNdef() {
nfcAdapter=NfcAdapter.getDefaultAdapter(this);
pendingIntent=PendingIntent.getActivity(MainActivity.this, 500, new Intent(this, getClass()).addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP), 0);
IntentFilter filter = new IntentFilter(NfcAdapter.ACTION_NDEF_DISCOVERED);
try {
filter.addDataType("*/*");
filters=new IntentFilter[]{filter};
} catch (IntentFilter.MalformedMimeTypeException e) {
e.printStackTrace();
}
if (nfcAdapter==null){
Toast.makeText(this,"不支持NFC功能",Toast.LENGTH_SHORT).show();
}else{
if (nfcAdapter.isEnabled()){
Toast.makeText(this,"NFC功能已打开",Toast.LENGTH_SHORT).show();
nfcAdapter.setNdefPushMessageCallback(this,this);
}else{
Intent intent= new Intent(Settings.ACTION_NFC_SETTINGS);
startActivity(intent);
}
}
}
@Override
protected void onResume() {
super.onResume();
//前台调度系统
nfcAdapter.enableForegroundDispatch(MainActivity.this,pendingIntent,filters,techLists);
}
@Override
protected void onPause() {
super.onPause();
nfcAdapter.disableForegroundDispatch(MainActivity.this);
}
} 标签的调度系统：(此方式需要Manifest文件配置三种Intent过滤器，ACTION_NDEF_DISCOVERED、ACTION_TECH_SDISCOVERED、ACTION_TAG_DISCOVERED
<!--NEDF_DISCOVERED-->
<intent-filter>
<action android:name="android.nfc.action.NDEF_DISCOVERED"></action>
<category android:name="android.intent.category.DEFAULT"></category>
<data android:mimeType="text/plain"></data>
</intent-filter>
<!--TECH_DISCOVERED-->
<intent-filter>
<action android:name="android.nfc.action.TECH_DISCOVERED"></action>
</intent-filter>
<!--Define in the xml of resource-->
<meta-data android:name="android.nfc.action.TECH_DISCOVERED"
android:resource="@xml/tech_list"></meta-data>
<!--TAG_DISCOVERED-->
<intent-filter>
<action android:name="android.nfc.action.TAG_DISCOVERED"></action>
</intent-filter> tech_list.xml:
<resources xmlns:xliff="urn:oasis:names:tc:xliff:document:1.2">
<tech-list>
<tech>android.nfc.tech.IsoDep</tech>
<tech>android.nfc.tech.NfcA</tech>
<tech>android.nfc.tech.NfcB</tech>
<tech>android.nfc.tech.NfcF</tech>
<tech>android.nfc.tech.NfcV</tech>
<tech>android.nfc.tech.Ndef</tech>
<tech>android.nfc.tech.NdefFormatable</tech>
<tech>android.nfc.tech.MifareClassic</tech>
<tech>android.nfc.tech.MifareUltralight</tech>
</tech-list>
</resources>
读写模式
NFC标签的读操作：
基本步骤：
第一：从intent里面获取到NDEFMessage;
第二：解析数据
文本的读操作：
String action=intent.getAction();
Tag tag=intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
if (NfcAdapter.ACTION_NDEF_DISCOVERED.equals(action)){
//第一步：获取NDEFMEssage
NdefMessage[] messages=null;
Parcelable[] rawMsgs=intent.getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES);
if (rawMsgs !=null){
messages = new NdefMessage[rawMsgs.length];
for (int i = 0; i <messages.length ; i++) {
messages[i]= (NdefMessage) rawMsgs[i];
}
}else{
byte[]empty=new byte[]{};
NdefRecord ndefRecord=new NdefRecord(NdefRecord.TNF_UNKNOWN,empty,empty,empty);
NdefMessage ndefMessage=new NdefMessage(new NdefRecord[]{ndefRecord});
messages = new NdefMessage[]{ndefMessage};
}
//第二步：解析文本数据
if (messages !=null &&messages.length>0){
for (int i = 0; i < messages.length; i++) {
int length=messages[i].getRecords().length;
NdefRecord[] records=messages[i].getRecords();
for (int j=0;j<length;j++){
for (NdefRecord ndefRecoder:records) {
//解析文本
if (isText){
//检查
Preconditions.checkArgument(Arrays.equals(ndefRecoder.getType(),NdefRecord.RTD_TEXT));
//获取payload内容
byte[] textPayload=ndefRecoder.getPayload();
//解析payload的第一个字节（包含编码格式，最高位为0的话，则为UTF-8;为1的话则为UTF-16）
Byte statuByte=ndefRecoder.getPayload()[0];
String textEncode;
if ((statuByte & 0x880)==0){
textEncode="UTF-8";
}else{
textEncode="UTF-16";
}
//获取language code,(通过第一个字节低五位，获取其长度)
int langLenth=statuByte&0x3F;
String langCode=new String(textPayload,1,langLenth,Charset.forName("UTF-8"));
try {
//获取真实文本的数据
String payloadText=new String(textPayload,langLenth+1,textPayload.length-langLenth-1,textEncode);
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
} Absolute_uri格式：
String action=intent.getAction();
Tag tag=intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
if (NfcAdapter.ACTION_NDEF_DISCOVERED.equals(action)){
//第一步：获取NDEFMEssage
NdefMessage[] messages=null;
Parcelable[] rawMsgs=intent.getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES);
if (rawMsgs !=null){
messages = new NdefMessage[rawMsgs.length];
for (int i = 0; i <messages.length ; i++) {
messages[i]= (NdefMessage) rawMsgs[i];
}
}else{
byte[]empty=new byte[]{};
NdefRecord ndefRecord=new NdefRecord(NdefRecord.TNF_UNKNOWN,empty,empty,empty);
NdefMessage ndefMessage=new NdefMessage(new NdefRecord[]{ndefRecord});
messages = new NdefMessage[]{ndefMessage};
}
//第二步：解析数据
if (messages !=null &&messages.length>0){
for (int i = 0; i < messages.length; i++) {
int length=messages[i].getRecords().length;
NdefRecord[] records=messages[i].getRecords();
for (int j=0;j<length;j++){
for (NdefRecord ndefRecoder:records) {
byte[] abPayload=ndefRecoder.getPayload();
Uri uri=Uri.parse(new String(abPayload,Charset.forName("UTF-8")));
}
}
}
} Well_know_Uri:
String action=intent.getAction();
Tag tag=intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
if (NfcAdapter.ACTION_NDEF_DISCOVERED.equals(action)){
//第一步：获取NDEFMEssage
NdefMessage[] messages=null;
Parcelable[] rawMsgs=intent.getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES);
if (rawMsgs !=null){
messages = new NdefMessage[rawMsgs.length];
for (int i = 0; i <messages.length ; i++) {
messages[i]= (NdefMessage) rawMsgs[i];
}
}else{
byte[]empty=new byte[]{};
NdefRecord ndefRecord=new NdefRecord(NdefRecord.TNF_UNKNOWN,empty,empty,empty);
NdefMessage ndefMessage=new NdefMessage(new NdefRecord[]{ndefRecord});
messages = new NdefMessage[]{ndefMessage};
}
//第二步：解析数据
if (messages !=null &&messages.length>0){
for (int i = 0; i < messages.length; i++) {
int length=messages[i].getRecords().length;
NdefRecord[] records=messages[i].getRecords();
for (int j=0;j<length;j++){
for (NdefRecord ndefRecoder:records) {
Preconditions.checkArgument(Arrays.equals(ndefRecoder.getType(),NdefRecord.RTD_URI));
byte[] payload=ndefRecoder.getPayload();
String prefix=URI_PREFIX_MAP.get(payload[0]);
byte[] fullUri= Bytes.concat(prefix.getBytes(Charset.forName("UTF-8")), Arrays.copyOfRange(payload, 1, payload.length));
Uri uri=Uri.parse(new String(fullUri));
}
}
}
}
写操作：
1、Reading NDEF data from an NFC tag
2、Beaming NDEF messages from one device to another with Android Beam™。
在安卓系统的应用中，最主要的有两种应用场景，第一个就是读取NEC标签里面的NDEF格式的数据，第二个就是不同设备间的NDEF信息数据的操作。接下来就主要学习一下这两块的实际应用。
首先学习一下基础知识：
一、权限的声明：
<uses-permission android:name="android.permission.NFC" />
<uses-sdk android:minSdkVersion="10"/>
<uses-feature android:name="android.hardware.nfc" android:required="true" />二、检查设备是否支持NFC
private NfcAdapter nfcAdapter;
private PendingIntent pendingIntent;
private IntentFilter[] filters;
private String[][] techLists=null;
private void checkNdef() {
nfcAdapter=NfcAdapter.getDefaultAdapter(this);
pendingIntent=PendingIntent.getActivity(MainActivity.this, 500, new Intent(this, getClass()).addFlags(Intent.FLAG_ACTIVITY_S INGLE_TOP), 0);
IntentFilter filter = new IntentFilter(NfcAdapter.ACTION_NDEF_DISCOVERED);
try {
filter.addDataType("*/*");
filters=new IntentFilter[]{filter};
} catch (IntentFilter.MalformedMimeTypeException e) {
e.printStackTrace();
}
if (nfcAdapter==null){
Toast.makeText(this,"不支持NFC功能",Toast.LENGTH_SHORT).show();
}else{
if (nfcAdapter.isEnabled()){
Toast.makeText(this,"NFC功能已打开",Toast.LENGTH_SHORT).show();
nfcAdapter.setNdefPushMessageCallback(this,this);
}else{
Intent intent= new Intent(Settings.ACTION_NFC_SETTINGS);
startActivity(intent);
}
}
} 三、NFC调度方式：前台调度和标签调度所谓前台调度就是指我们直接在一个当前运行程序的Activity中显式的应用NFC；而标签调度就是指我们在我们的应用程序中配置好相关的Intent-filter,当设备接触到NFC标签的时候会调用有该配置的应用程序。
前台调度方式：（Manifest文件下的配置不做任何调整，只是声明一个普通的Activity即可）
public class MainActivity extends AppCompatActivity implements NfcAdapter.CreateNdefMessageCallback{
private NfcAdapter nfcAdapter;
private PendingIntent pendingIntent;
private IntentFilter[] filters;
private String[][] techLists=null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
checkNdef();
}
private void checkNdef() {
nfcAdapter=NfcAdapter.getDefaultAdapter(this);
pendingIntent=PendingIntent.getActivity(MainActivity.this, 500, new Intent(this, getClass()).addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP), 0);
IntentFilter filter = new IntentFilter(NfcAdapter.ACTION_NDEF_DISCOVERED);
try {
filter.addDataType("*/*");
filters=new IntentFilter[]{filter};
} catch (IntentFilter.MalformedMimeTypeException e) {
e.printStackTrace();
}
if (nfcAdapter==null){
Toast.makeText(this,"不支持NFC功能",Toast.LENGTH_SHORT).show();
}else{
if (nfcAdapter.isEnabled()){
Toast.makeText(this,"NFC功能已打开",Toast.LENGTH_SHORT).show();
nfcAdapter.setNdefPushMessageCallback(this,this);
}else{
Intent intent= new Intent(Settings.ACTION_NFC_SETTINGS);
startActivity(intent);
}
}
}
@Override
protected void onResume() {
super.onResume();
//前台调度系统
nfcAdapter.enableForegroundDispatch(MainActivity.this,pendingIntent,filters,techLists);
}
@Override
protected void onPause() {
super.onPause();
nfcAdapter.disableForegroundDispatch(MainActivity.this);
}
} 标签的调度系统：(此方式需要Manifest文件配置三种Intent过滤器，ACTION_NDEF_DISCOVERED、ACTION_TECH_SDISCOVERED、ACTION_TAG_DISCOVERED
<!--NEDF_DISCOVERED-->
<intent-filter>
<action android:name="android.nfc.action.NDEF_DISCOVERED"></action>
<category android:name="android.intent.category.DEFAULT"></category>
<data android:mimeType="text/plain"></data>
</intent-filter>
<!--TECH_DISCOVERED-->
<intent-filter>
<action android:name="android.nfc.action.TECH_DISCOVERED"></action>
</intent-filter>
<!--Define in the xml of resource-->
<meta-data android:name="android.nfc.action.TECH_DISCOVERED"
android:resource="@xml/tech_list"></meta-data>
<!--TAG_DISCOVERED-->
<intent-filter>
<action android:name="android.nfc.action.TAG_DISCOVERED"></action>
</intent-filter> tech_list.xml:
<resources xmlns:xliff="urn:oasis:names:tc:xliff:document:1.2">
<tech-list>
<tech>android.nfc.tech.IsoDep</tech>
<tech>android.nfc.tech.NfcA</tech>
<tech>android.nfc.tech.NfcB</tech>
<tech>android.nfc.tech.NfcF</tech>
<tech>android.nfc.tech.NfcV</tech>
<tech>android.nfc.tech.Ndef</tech>
<tech>android.nfc.tech.NdefFormatable</tech>
<tech>android.nfc.tech.MifareClassic</tech>
<tech>android.nfc.tech.MifareUltralight</tech>
</tech-list>
</resources>
读写模式
NFC标签的读操作：
基本步骤：
第一：从intent里面获取到NDEFMessage;
第二：解析数据
文本的读操作：
String action=intent.getAction();
Tag tag=intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
if (NfcAdapter.ACTION_NDEF_DISCOVERED.equals(action)){
//第一步：获取NDEFMEssage
NdefMessage[] messages=null;
Parcelable[] rawMsgs=intent.getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES);
if (rawMsgs !=null){
messages = new NdefMessage[rawMsgs.length];
for (int i = 0; i <messages.length ; i++) {
messages[i]= (NdefMessage) rawMsgs[i];
}
}else{
byte[]empty=new byte[]{};
NdefRecord ndefRecord=new NdefRecord(NdefRecord.TNF_UNKNOWN,empty,empty,empty);
NdefMessage ndefMessage=new NdefMessage(new NdefRecord[]{ndefRecord});
messages = new NdefMessage[]{ndefMessage};
}
//第二步：解析文本数据
if (messages !=null &&messages.length>0){
for (int i = 0; i < messages.length; i++) {
int length=messages[i].getRecords().length;
NdefRecord[] records=messages[i].getRecords();
for (int j=0;j<length;j++){
for (NdefRecord ndefRecoder:records) {
//解析文本
if (isText){
//检查
Preconditions.checkArgument(Arrays.equals(ndefRecoder.getType(),NdefRecord.RTD_TEXT));
//获取payload内容
byte[] textPayload=ndefRecoder.getPayload();
//解析payload的第一个字节（包含编码格式，最高位为0的话，则为UTF-8;为1的话则为UTF-16）
Byte statuByte=ndefRecoder.getPayload()[0];
String textEncode;
if ((statuByte & 0x880)==0){
textEncode="UTF-8";
}else{
textEncode="UTF-16";
}
//获取language code,(通过第一个字节低五位，获取其长度)
int langLenth=statuByte&0x3F;
String langCode=new String(textPayload,1,langLenth,Charset.forName("UTF-8"));
try {
//获取真实文本的数据
String payloadText=new String(textPayload,langLenth+1,textPayload.length-langLenth-1,textEncode);
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
} Absolute_uri格式：
String action=intent.getAction();
Tag tag=intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
if (NfcAdapter.ACTION_NDEF_DISCOVERED.equals(action)){
//第一步：获取NDEFMEssage
NdefMessage[] messages=null;
Parcelable[] rawMsgs=intent.getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES);
if (rawMsgs !=null){
messages = new NdefMessage[rawMsgs.length];
for (int i = 0; i <messages.length ; i++) {
messages[i]= (NdefMessage) rawMsgs[i];
}
}else{
byte[]empty=new byte[]{};
NdefRecord ndefRecord=new NdefRecord(NdefRecord.TNF_UNKNOWN,empty,empty,empty);
NdefMessage ndefMessage=new NdefMessage(new NdefRecord[]{ndefRecord});
messages = new NdefMessage[]{ndefMessage};
}
//第二步：解析数据
if (messages !=null &&messages.length>0){
for (int i = 0; i < messages.length; i++) {
int length=messages[i].getRecords().length;
NdefRecord[] records=messages[i].getRecords();
for (int j=0;j<length;j++){
for (NdefRecord ndefRecoder:records) {
byte[] abPayload=ndefRecoder.getPayload();
Uri uri=Uri.parse(new String(abPayload,Charset.forName("UTF-8")));
}
}
}
} Well_know_Uri:
String action=intent.getAction();
Tag tag=intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
if (NfcAdapter.ACTION_NDEF_DISCOVERED.equals(action)){
//第一步：获取NDEFMEssage
NdefMessage[] messages=null;
Parcelable[] rawMsgs=intent.getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES);
if (rawMsgs !=null){
messages = new NdefMessage[rawMsgs.length];
for (int i = 0; i <messages.length ; i++) {
messages[i]= (NdefMessage) rawMsgs[i];
}
}else{
byte[]empty=new byte[]{};
NdefRecord ndefRecord=new NdefRecord(NdefRecord.TNF_UNKNOWN,empty,empty,empty);
NdefMessage ndefMessage=new NdefMessage(new NdefRecord[]{ndefRecord});
messages = new NdefMessage[]{ndefMessage};
}
//第二步：解析数据
if (messages !=null &&messages.length>0){
for (int i = 0; i < messages.length; i++) {
int length=messages[i].getRecords().length;
NdefRecord[] records=messages[i].getRecords();
for (int j=0;j<length;j++){
for (NdefRecord ndefRecoder:records) {
Preconditions.checkArgument(Arrays.equals(ndefRecoder.getType(),NdefRecord.RTD_URI));
byte[] payload=ndefRecoder.getPayload();
String prefix=URI_PREFIX_MAP.get(payload[0]);
byte[] fullUri= Bytes.concat(prefix.getBytes(Charset.forName("UTF-8")), Arrays.copyOfRange(payload, 1, payload.length));
Uri uri=Uri.parse(new String(fullUri));
}
}
}
}
写操作：
TNF_WELL_KNOWN with RTD_TEXT
<span style="color:rgba(0, 0, 0, 0.870588235294118);"> </span><span style="color:#333333;">public static NdefMessage writeText(String payload, Locale locale, boolean encodeInUtf8){
byte[] langBytes = locale.getLanguage().getBytes(Charset.forName("US-ASCII"));
Charset utfEncoding = encodeInUtf8 ? Charset.forName("UTF-8") : Charset.forName("UTF-16");
byte[] textBytes = payload.getBytes(utfEncoding);
int utfBit = encodeInUtf8 ? 0 : (1 << 7);
char status = (char) (utfBit + langBytes.length);
byte[] data = new byte[1 + langBytes.length + textBytes.length];
data[0] = (byte) status;
System.arraycopy(langBytes, 0, data, 1, langBytes.length);
System.arraycopy(textBytes, 0, data, 1 + langBytes.length, textBytes.length);
NdefRecord record = new NdefRecord(NdefRecord.TNF_WELL_KNOWN,
NdefRecord.RTD_TEXT, new byte[0], data);
return new NdefMessage(new NdefRecord[]{record});
}</span>
TNF_ABSOLUTE_URI
public static NdefMessage writeAbsoluteUri(String uri){
NdefRecord uriRecord = new NdefRecord(
NdefRecord.TNF_ABSOLUTE_URI ,
uri.getBytes(Charset.forName("US-ASCII")),
new byte[0], new byte[0]);
return new NdefMessage(new NdefRecord[]{uriRecord});
}
TNF_WELL_KNOWN with RTD_URI
public static NdefMessage writeWellKnowUri(String uri){
byte[] uriField = uri.getBytes(Charset.forName("US-ASCII"));
byte[] payload = new byte[uriField.length + 1]; //add 1 for the URI Prefix
payload[0] = 0x01; //prefixes http://www. to the URI
System.arraycopy(uriField, 0, payload, 1, uriField.length); //appends URI to payload
NdefRecord rtdUriRecord = new NdefRecord( NdefRecord.TNF_WELL_KNOWN, NdefRecord.RTD_URI, new byte[0], payload);
return new NdefMessage(new NdefRecord[]{<span style="font-family: Roboto, sans-serif;">rtdUriRecord </span>});
}<span style="font-size:18px;font-family: Arial, Helvetica, sans-serif; background-color: rgb(255, 255, 255);"><strong> </strong> </span><span style="font-size:14px;font-family: Arial, Helvetica, sans-serif; background-color: rgb(255, 255, 255);"> </span>
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