文章目录
- 前言
- NFC 能做什么
- NFC示例
- 配置
- AndroidManifest
- 小结
- 番外
- 写白卡
- 模拟卡
前言
最近在玩NFC的功能,感觉NFC的蕴含了巨大的能量,脑海中浮现各种骚操作,心情有点小激动。当然网上不乏许多优秀的文章,这里笔者只是给出自己得理解,方便快速掌握。
NFC 能做什么
- 老人小孩 自动打电话功能
- WIFI贴卡自动连接
- 语音留言
- 家长模式,监控小孩玩手机
NFC示例
这里从demo入手,站在巨人得肩膀上我们能走得更远 ,文末给出源码地址
配置
CardEmulation(卡片模拟)
- AndroidManifest
标准写法直接梭哈
<?xml version="1.0" encoding="UTF-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.android.cardemulation"
android:versionCode="1"
android:versionName="1.0">
<uses-permission android:name="android.permission.NFC" />
<!--API 9 设备可以使用近场通信(NFC)进行通信。-->
<uses-feature
android:name="android.hardware.nfc"
android:required="true" />
<!--API 19 该设备支持基于主机的NFC卡仿真。-->
<uses-feature
android:name="android.hardware.nfc.hcef"
android:required="true" />
<!--API 24 该设备支持基于主机的NFC-F卡仿真。-->
<uses-feature
android:name="android.hardware.nfc.hce"
android:required="true" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.NFC_TRANSACTION_EVENT"/>
<uses-permission android:name="android.permission.BIND_NFC_SERVICE"/>
<application android:allowBackup="true"
android:label="@string/app_name"
android:icon="@drawable/ic_launcher"
android:theme="@style/AppTheme">
<!-- Basic UI for sample discoverability. -->
<activity android:name=".MainActivity"
android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<!-- Service for handling communication with NFC terminal. -->
<service android:name=".CardService"
android:exported="true"
android:permission="android.permission.BIND_NFC_SERVICE">
<!-- Intent filter indicating that we support card emulation. -->
<intent-filter>
<action android:name="android.nfc.cardemulation.action.HOST_APDU_SERVICE"/>
</intent-filter>
<!-- Required XML configuration file, listing the AIDs that we are emulating cards
for. This defines what protocols our card emulation service supports. -->
<meta-data android:name="android.nfc.cardemulation.host_apdu_service"
android:resource="@xml/aid_list"/>
</service>
</application>
</manifest>
aid_list
作为模拟卡3000000002
即为其卡号,也是建立连接得唯一标识,这里理解即可,不必深究。
- category
还有一个模式为payment,即付款应用,貌似是说可以自动启动,试了下没成功,此处先不管 - android:description 自动唤起时,后台显示名称,当然还能配置图标,怎么配
<?xml version="1.0" encoding="utf-8"?>
<host-apdu-service xmlns:android="http://schemas.android.com/apk/res/android"
android:description="@string/service_name"
android:requireDeviceUnlock="false">
<aid-group android:description="@string/card_title" android:category="other">
<aid-filter android:name="3000000002"/>
</aid-group>
</host-apdu-service>
绑定服务
下面是标准代码,且必须在onResume和onPause处开关nfc
public class MainActivity extends SampleActivityBase {
public static final String TAG = "MainActivity";
private boolean mLogShown;
private CardEmulation mCardEmulation;
private ComponentName mService;
private static List<String> AIDS = new ArrayList<>();
private NfcAdapter mNfcAdapter;
private PendingIntent mPendingIntent;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mNfcAdapter = NfcAdapter.getDefaultAdapter(this);
mCardEmulation = CardEmulation.getInstance(mNfcAdapter);
mService = new ComponentName(this, CardService.class);
AIDS.add(CardService.SAMPLE_LOYALTY_CARD_AID);
}
@Override
protected void onResume() {
super.onResume();
mCardEmulation.setPreferredService(this, mService);
mCardEmulation.registerAidsForService(mService, "other", AIDS);
}
@Override
protected void onPause() {
super.onPause();
mNfcAdapter.disableForegroundDispatch(this);
mCardEmulation.removeAidsForService(mService, "other");
}
}
HostApduService
开启服务,此服务主要是进行命令收发,着重讲一下其思路和流程
- AID,即卡号需要与前面的
aid-filter
对应
// AID for our loyalty card service.
public static final String SAMPLE_LOYALTY_CARD_AID = "3000000002";
- 理解为握手标志,验证用,其实也可以不要
// Format: [Class | Instruction | Parameter 1 | Parameter 2]
private static final String SELECT_APDU_HEADER = "00A40400";
- 具体传输数据标志,比如笔者这里会加入一个JSON
// Format: [Class | Instruction | Parameter 1 | Parameter 2]
private static final String GET_DATA_APDU_HEADER = "00CA0000";
- SELECT_OK_SW : 成功标志,加到实际数据数组尾部
- UNKNOWN_CMD_SW : 错误标志,加到实际数据数组尾部
因为全程为buffer传输,所以会有很多的数组切割和转换操作,这个应该不算复杂
// "OK" status word sent in response to SELECT AID command (0x9000)
private static final byte[] SELECT_OK_SW = HexStringToByteArray("9000");
// "UNKNOWN" status word sent in response to invalid APDU command (0x0000)
private static final byte[] UNKNOWN_CMD_SW = HexStringToByteArray("0000");
- 具体交互是怎么做的呢?(processCommandApdu)
对! 就是按照命令做一问一答
@Override
public byte[] processCommandApdu(byte[] commandApdu, Bundle extras) {
Toast.makeText(getApplicationContext(), "processCommandApdu", Toast.LENGTH_LONG);
Log.i(TAG, "Received APDU: " + ByteArrayToHexString(commandApdu));
if (Arrays.equals(SELECT_APDU, commandApdu)) {
return ConcatArrays("OK".getBytes(), SELECT_OK_SW);
} else if ((Arrays.equals(GET_DATA_APDU, commandApdu))) {
JSONObject jsonObject = new JSONObject();
try {
jsonObject.put("ssid", "cameraui");
jsonObject.put("password", "12345678");
} catch (JSONException e) {
}
String account = jsonObject.toString();
byte[] accountBytes = account.getBytes();
Log.i(TAG, "Sending account number: " + account);
return ConcatArrays(accountBytes, SELECT_OK_SW);
} else {
return UNKNOWN_CMD_SW;
}
}
CardReader(读卡器)
AndroidManifest
标准写法,同样是梭哈
<?xml version="1.0" encoding="UTF-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.android.cardreader"
android:versionCode="1"
android:versionName="1.0">
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.CHANGE_NETWORK_STATE" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<!-- NFC Reader Mode was added in API 19. -->
<uses-permission android:name="android.permission.NFC" />
<uses-feature android:name="android.hardware.nfc" android:required="true" />
<application android:allowBackup="true"
android:label="@string/app_name"
android:icon="@drawable/ic_launcher"
android:theme="@style/AppTheme">
<activity android:name=".MainActivity"
android:label="@string/app_name"
android:launchMode="singleTop">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
<intent-filter>
<action android:name="android.nfc.action.NDEF_DISCOVERED" />
<category android:name="android.intent.category.DEFAULT" />
<data android:mimeType="*/*" />
<!--<data-->
<!--android:host="ext"-->
<!--android:pathPrefix="/vndcn.com:nfc"-->
<!--android:scheme="vnd.android.nfc" />-->
</intent-filter>
<intent-filter>
<action android:name="android.nfc.action.TAG_DISCOVERED" />
<category android:name="android.intent.category.DEFAULT" />
<data android:mimeType="*/*" />
</intent-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/nfc_tech_filter" />
</activity>
</application>
</manifest>
nfc_tech_filter
标签列表,全兼容就是了
<?xml version="1.0" encoding="utf-8"?>
<!-- This file is used as part of the filter for incoming NFC TECH_DISCOVERED intents. -->
<resources xmlns:android="http://schemas.android.com/apk/res/android">
<tech-list>
<tech>android.nfc.tech.IsoDep</tech>
</tech-list>
<tech-list>
<tech>android.nfc.tech.NfcA</tech>
</tech-list>
<tech-list>
<tech>android.nfc.tech.NfcB</tech>
</tech-list>
<tech-list>
<tech>android.nfc.tech.NfcF</tech>
</tech-list>
<tech-list>
<tech>android.nfc.tech.NfcV</tech>
</tech-list>
<tech-list>
<tech>android.nfc.tech.Ndef</tech>
</tech-list>
<tech-list>
<tech>android.nfc.tech.NdefFormatable</tech>
</tech-list>
<tech-list>
<tech>android.nfc.tech.MifareClassic</tech>
</tech-list>
<tech-list>
<tech>android.nfc.tech.MifareUltralight</tech>
</tech-list>
</resources>
读卡页面
笔者自己写的读卡页面,支持命令交互和系统启动即nfc卡片启动方式,直接继承即可
/**
* 文件名:NFCActivity
* 描 述:
* 作 者:05878mq
* 时 间:2022/8/16 15:28
*/
abstract public class NFCActivity implements LoyaltyCardReader.AccountCallback {
final static String TAG = NFCActivity.class.getSimpleName();
//支持的标签类型
private final int nfcFlag = NfcAdapter.FLAG_READER_NO_PLATFORM_SOUNDS
| NfcAdapter.FLAG_READER_NFC_A
| NfcAdapter.FLAG_READER_NFC_B
| NfcAdapter.FLAG_READER_NFC_BARCODE
| NfcAdapter.FLAG_READER_NFC_F
| NfcAdapter.FLAG_READER_NFC_V;
@Override
public void onPause() {
disableReaderMode();
super.onPause();
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.i(TAG, "getIntent()" +getIntent());
disposeIntent(getIntent());
}
@Override
public void onResume() {
try {
enableReaderMode();
} catch (IntentFilter.MalformedMimeTypeException e) {
e.printStackTrace();
}
super.onResume();
}
private void disableReaderMode() {
Log.i(TAG, "Disabling reader mode");
NfcAdapter nfc = NfcAdapter.getDefaultAdapter(this);
if (nfc != null) {
//nfc.disableReaderMode(this);
nfc.disableForegroundDispatch(this);
}
}
private void enableReaderMode() throws IntentFilter.MalformedMimeTypeException {
Log.i(TAG, "Enabling reader mode");
NfcAdapter nfc = NfcAdapter.getDefaultAdapter(this);
if (nfc != null) {
IntentFilter[] FILTERS = new IntentFilter[]{new IntentFilter(
NfcAdapter.ACTION_TECH_DISCOVERED, "*/*")};
String[][] TECHLISTS = new String[][]{{IsoDep.class.getName()},
{NfcV.class.getName()}, {NfcF.class.getName()},};
PendingIntent pendingIntent = PendingIntent.getActivity(this, 0,
new Intent(this, this.getClass()).addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP), 0);
nfc.enableForegroundDispatch(this, pendingIntent, FILTERS, TECHLISTS);
nfc.enableReaderMode(this, new LoyaltyCardReader(this), nfcFlag, new Bundle());
}
}
@Override
protected void onNewIntent(Intent intent) {
super.onNewIntent(intent);
// if (NfcAdapter.ACTION_NDEF_DISCOVERED == intent.getAction()) {
// new LoyaltyCardReader(this).onTagDiscovered(intent.getParcelableExtra(NfcAdapter.EXTRA_TAG));
// }
disposeIntent(intent);
}
private void disposeIntent(Intent intent) {
Log.d("NfcAdapter", getIntent().getAction());
if (NfcAdapter.ACTION_NDEF_DISCOVERED == intent.getAction()) {
String cardId = getCardId(intent);
if (cardId != null) {
Log.d(TAG, String.format("NFC ID:%s", cardId));
} else {
Log.d(TAG, "未读取到卡ID");
}
}
}
private void readNfcTag(Intent intent) {
if (NfcAdapter.ACTION_NDEF_DISCOVERED.equals(intent.getAction())) {
Parcelable[] rawMsgs = intent.getParcelableArrayExtra(
NfcAdapter.EXTRA_NDEF_MESSAGES);
NdefMessage msgs[] = null;
int contentSize = 0;
if (rawMsgs != null) {
msgs = new NdefMessage[rawMsgs.length];
for (int i = 0; i < rawMsgs.length; i++) {
msgs[i] = (NdefMessage) rawMsgs[i];
contentSize += msgs[i].toByteArray().length;
}
}
try {
if (msgs != null) {
NdefRecord record = msgs[0].getRecords()[0];
//byte[] payload = record.getPayload();
//String res = new String(payload);
//数据格式定义 前两字节表示编码类型
//
String res = TextRecord.parseCustom(record).getText();
Log.d(TAG, "content url is: " + res);
getNFCInfoSuccess(res);
}
} catch (Exception e) {
}
}
}
protected abstract void getNFCInfoSuccess(String res);
private String getCardId(Intent intent) {
Tag tagFromIntent = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
byte[] bytesId = tagFromIntent.getId();
readNfcTag(intent);
Ndef ndef = Ndef.get(tagFromIntent);
return LoyaltyCardReader.ByteArrayToHexString(bytesId);
}
}
标签的解析
TXT 数据格式定义 前两字节表示编码类型 参考下面连接
自定义格式 使用 parseCustom
/**
* 文件名:SS
* 描 述:
* 作 者:05878mq
* 时 间:2022/8/19 17:20
*/
public class TextRecord {
private final String mText;
private TextRecord(String text) {
mText = text;
}
public String getText() {
return mText;
}
public static TextRecord parse(NdefRecord ndefRecord) {
/*
* 1,判断数据是否为NDEF格式
*/
// verify tnf
//第一个判断,TNF(类型名格式,Type Name Format)必须是NdefRecord.TNF_WELL_KNOWN
if (ndefRecord.getTnf() != NdefRecord.TNF_WELL_KNOWN) {
return null;
}
//第二个判断,可变的长度类型必须是NdefRecord.RTD_TEXT。
if (!Arrays.equals(ndefRecord.getType(), NdefRecord.RTD_TEXT)) {
return null;
}
try {
/*
* 2,取得读到的ndef字节流,
* 第1个字节描述了数据的状态,然后若干个字节描述文本的语言编码,最后剩余字节表示文本数据
*/
byte[] payload = ndefRecord.getPayload();
/*
* 3,解析第1个字节最高位,第7位:本流的字符编码值, 若值是0是UTF8,1是UTF16
* 注意 字符编码与语言编码不同.
*/
String textEncoding = ((payload[0] & 0x80) == 0) ? "UTF-8" : "UTF-16";
//第1个字节第6位总为0
/*
* 4,解析第1个字节0-5位,它存放语言编码的长度值
* 注意 字符编码与语言编码不同.
*/
int languageCodeLength = payload[0] & 0x3f;
/*
* 5,解析语言编码
*/
String languageCode = new String(payload, 1, languageCodeLength, "US-ASCII");
/*
* 6,解析出文本内容
*/
String text = new String(payload, languageCodeLength + 1,
payload.length - languageCodeLength - 1, textEncoding);
/*
* 7,返回解析结果
*/
return new TextRecord(text);
} catch (Exception e) {
throw new IllegalArgumentException();
}
}
public static TextRecord parseCustom(NdefRecord ndefRecord) {
/*
* 1,判断数据是否为NDEF格式
*/
// verify tnf
//第一个判断,TNF(类型名格式,Type Name Format)必须是NdefRecord.TNF_WELL_KNOWN
if (ndefRecord.getTnf() != NdefRecord.TNF_MIME_MEDIA) {
return null;
}
//第二个判断,可变的长度类型必须是NdefRecord.RTD_TEXT。
byte[] CustomType = "application/xxx.xxx.xxx.android.nfc".getBytes();
if (!Arrays.equals(ndefRecord.getType(), CustomType)) {
return null;
}
try {
/*
* 2,取得读到的ndef字节流,
* 第1个字节描述了数据的状态,然后若干个字节描述文本的语言编码,最后剩余字节表示文本数据
*/
byte[] payload = ndefRecord.getPayload();
/*
* 6,解析出文本内容
*/
String text = new String(payload, "UTF-8");
/*
* 7,返回解析结果
*/
return new TextRecord(text);
} catch (Exception e) {
throw new IllegalArgumentException();
}
}
}
解析成功回调getNFCInfoSuccess
小结
到此一个标准的读写流程已经完成,此时我们仍然需要手动打开自己的APP,然后进行数据交互
那么如何能不开启APP直接拿想要的json数据,并进行下一步操作,答案是直接卡刷启动, 前面代码中注意到 byte[] CustomType = "application/xxx.xxx.xxx.android.nfc".getBytes();
此处即自定义标签,可打开指定APP并传输自定义数据。
番外
写白卡
主要是TagWriter 可写入包名和自定义文本,当然只是辅助工具,我们最终还是要自己实现该功能
- 代码实现
private void writeNFC(Tag tag, String content) {
// 这里是将数据写入NFC卡中
// NdefRecord record1 = NdefRecord.createApplicationRecord("xxx.xxx.xxx.xxx");
// NdefRecord record2 = NdefRecord.createExternal("xxx.xxx", "nfc", content.getBytes());
// NdefRecord record2 = NdefRecord.createExternal("xxx.xxx", "nfc", "{\"ssid\":\"cameraui\",\"password\":\"12345678\"}".getBytes());
// NdefRecord record1 = NdefRecord.createApplicationRecord("com.guide.capp");
// NdefRecord record2 = NdefRecord.createExternal("xxx.xxx.xxx", "nfc", "{\"ssid\":\"cameraui\",\"password\":\"12345678\"}".getBytes());
String mimeType = "application/xxx.xxx.xxx.android.nfc";
byte[] mimeBytes = mimeType.getBytes(Charset.forName("UTF-8"));
byte[] dataBytes = "{\"ssid\":\"cameraui\",\"password\":\"12345678\"}".getBytes(Charset.forName("UTF-8"));
byte[] id = new byte[0];
NdefRecord record3 = new NdefRecord(NdefRecord.TNF_MIME_MEDIA, mimeBytes, id, dataBytes);
NdefRecord[] nfcs = {record3};
//NdefRecord[] nfcs = {record1, record2};
NdefMessage ndefMessage = new NdefMessage(nfcs);
int size = ndefMessage.toByteArray().length;
try {
Ndef ndef = Ndef.get(tag);
if (ndef != null) {
ndef.connect();
if (!ndef.isWritable()) {
return;
}
if (ndef.getMaxSize() < size) {
return;
}
try {
ndef.writeNdefMessage(ndefMessage);
Toast.makeText(this, "写入成功", Toast.LENGTH_LONG).show();
} catch (FormatException e) {
e.printStackTrace();
}
} else {
NdefFormatable format = NdefFormatable.get(tag);
format.connect();
format.format(ndefMessage);
if (format.isConnected()) {
format.close();
}
Toast.makeText(this, "写入成功", Toast.LENGTH_LONG).show();
}
} catch (Exception e) {
e.printStackTrace();
Toast.makeText(this, "写入失败", Toast.LENGTH_LONG).show();
}
}
这样只能写入一张实体卡,虽然能直接启动APP并执行相关操作,但是无卡的情况下,直接手机模拟ic卡岂不是更加完美
模拟卡
先分享一个软件 NFC卡模拟 主要是利用他的模拟卡功能,当然你的手机需要root,所以这是一条不归路,除非定制的手机,不建议这样玩,但这与笔者推出编译Android源码的想法不谋而合,Framework一直是笔者追求,所谓任重而道远,也祝学习的路上大家都更上一层楼,后会有期咯。
https://github.com/championswimmer/NFC-host-card-emulation-Android