NfcA.transceive(byte [] data)抛出TagLostException [英] NfcA.transceive(byte[] data) throws TagLostException
本文介绍了NfcA.transceive(byte [] data)抛出TagLostException的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
所有操作均在此处开始.那里的问题已经解决，现在我在使用收发方法时遇到了问题.
It all started here. The problem over there was solved, now I'm facing problems with using the transceive method.
我的代码如下:
private void writeAndProtectTag(final Intent intent, final String message) {
// Run the entire process in its own thread as NfcA.transceive(byte[] data);
// Should not be run in main thread according to <https://developer.android.com/reference/android/nfc/tech/NfcA.html#transceive(byte[])>
(new Thread(new Runnable() {
// Password has to be 4 characters
// Password Acknowledge has to be 2 characters
byte[] pwd = "-_bA".getBytes();
byte[] pack = "cC".getBytes();
@Override
public void run() {
// Store tag object for use in NfcA and Ndef
Tag tag = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
// Using NfcA instead of MifareUltralight should make no difference in this method
NfcA nfca = null;
// Whole process is put into a big try-catch trying to catch the transceive's IOException
try {
nfca = NfcA.get(tag);
nfca.connect();
byte[] response;
// Authenticate with the tag first
// In case it's already been locked
try {
response = nfca.transceive(new byte[]{
(byte) 0x1B, // PWD_AUTH
pwd[0], pwd[1], pwd[2], pwd[3]
});
// Check if PACK is matching expected PACK
// This is a (not that) secure method to check if tag is genuine
if ((response != null) && (response.length >= 2)) {
byte[] packResponse = Arrays.copyOf(response, 2);
if (!(pack[0] == packResponse[0] && pack[1] == packResponse[1])) {
Toast.makeText(ctx, "Tag could not be authenticated:\n" + packResponse.toString() + "≠" + pack.toString(), Toast.LENGTH_LONG).show();
}
}
}catch(TagLostException e){
e.printStackTrace();
}
// Get Page 2Ah
response = nfca.transceive(new byte[] {
(byte) 0x30, // READ
(byte) 0x2A // page address
});
// configure tag as write-protected with unlimited authentication tries
if ((response != null) && (response.length >= 16)) { // read always returns 4 pages
boolean prot = false; // false = PWD_AUTH for write only, true = PWD_AUTH for read and write
int authlim = 0; // 0 = unlimited tries
nfca.transceive(new byte[] {
(byte) 0xA2, // WRITE
(byte) 0x2A, // page address
(byte) ((response[0] & 0x078) | (prot ? 0x080 : 0x000) | (authlim & 0x007)), // set ACCESS byte according to our settings
0, 0, 0 // fill rest as zeros as stated in datasheet (RFUI must be set as 0b)
});
}
// Get page 29h
response = nfca.transceive(new byte[] {
(byte) 0x30, // READ
(byte) 0x29 // page address
});
// Configure tag to protect entire storage (page 0 and above)
if ((response != null) && (response.length >= 16)) { // read always returns 4 pages
int auth0 = 0; // first page to be protected
nfca.transceive(new byte[] {
(byte) 0xA2, // WRITE
(byte) 0x29, // page address
response[0], 0, response[2], // Keep old mirror values and write 0 in RFUI byte as stated in datasheet
(byte) (auth0 & 0x0ff)
});
}
// Send PACK and PWD
// set PACK:
nfca.transceive(new byte[] {
(byte)0xA2,
(byte)0x2C,
pack[0], pack[1], 0, 0 // Write PACK into first 2 Bytes and 0 in RFUI bytes
});
// set PWD:
nfca.transceive(new byte[] {
(byte)0xA2,
(byte)0x2B,
pwd[0], pwd[1], pwd[2], pwd[3] // Write all 4 PWD bytes into Page 43
});
// Generate NdefMessage to be written onto the tag
NdefMessage msg = null;
try {
NdefRecord r1 = NdefRecord.createMime("text/plain", message.getBytes("UTF-8"));
NdefRecord r2 = NdefRecord.createApplicationRecord("com.example.alex.nfcapppcekunde");
msg = new NdefMessage(r1, r2);
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
byte[] ndefMessage = msg.toByteArray();
nfca.transceive(new byte[] {
(byte)0xA2, // WRITE
(byte)3, // block address
(byte)0xE1, (byte)0x10, (byte)0x12, (byte)0x00
});
// wrap into TLV structure
byte[] tlvEncodedData = null;
tlvEncodedData = new byte[ndefMessage.length + 3];
tlvEncodedData[0] = (byte)0x03; // NDEF TLV tag
tlvEncodedData[1] = (byte)(ndefMessage.length & 0x0FF); // NDEF TLV length (1 byte)
System.arraycopy(ndefMessage, 0, tlvEncodedData, 2, ndefMessage.length);
tlvEncodedData[2 + ndefMessage.length] = (byte)0xFE; // Terminator TLV tag
// fill up with zeros to block boundary:
tlvEncodedData = Arrays.copyOf(tlvEncodedData, (tlvEncodedData.length / 4 + 1) * 4);
for (int i = 0; i < tlvEncodedData.length; i += 4) {
byte[] command = new byte[] {
(byte)0xA2, // WRITE
(byte)((4 + i / 4) & 0x0FF), // block address
0, 0, 0, 0
};
System.arraycopy(tlvEncodedData, i, command, 2, 4);
try {
response = nfca.transceive(command);
} catch (IOException e) {
e.printStackTrace();
}
}
runOnUiThread(new Runnable() {
@Override
public void run() {
//UI related things, not important for NFC
btn.setImageResource(R.drawable.arrow_red);
tv.setText("");
}
});
curAction = "handle";
try {
nfca.close();
} catch (IOException e) {
e.printStackTrace();
}
} catch (IOException e) {
//Trying to catch any ioexception that may be thrown
e.printStackTrace();
} catch (Exception e) {
//Trying to catch any exception that may be thrown
e.printStackTrace();
}
}
})).start();
}
在使用 Ndef 类写到标签上的旧代码版本中，我没有这个问题.现在，我更改了一些内容，然后得到了两个 TagLostException s:
In my old code version that used Ndef class to write onto the tag I didn't have this problem. Now that I changed a few things I am getting two TagLostExceptions:
- PWD_AUTH行中的一个命令失败，但捕获了它的异常，这实际上与我正在扫描的标签一样，没有设置密码.
- 来自收发器的另一个，用于读取配置.
在第二个 TagLostException 之后，该方法当然结束了.在读取配置时，我不应该得到 TagLostException .有人知道那里发生了什么吗?
After the second TagLostException the method ends of course. When reading the configuration I should not get a TagLostException. Does anyone know what is going on there?
以下是例外:
android.nfc.TagLostException: Tag was lost.
at android.nfc.TransceiveResult.getResponseOrThrow(TransceiveResult.java:48)
at android.nfc.tech.BasicTagTechnology.transceive(BasicTagTechnology.java:151)
at android.nfc.tech.NfcA.transceive(NfcA.java:129)
at com.example.alex.nfcapppce.MainActivity$2.run(MainActivity.java:134)
at java.lang.Thread.run(Thread.java:761)
android.nfc.TagLostException: Tag was lost.
at android.nfc.TransceiveResult.getResponseOrThrow(TransceiveResult.java:48)
at android.nfc.tech.BasicTagTechnology.transceive(BasicTagTechnology.java:151)
at android.nfc.tech.NfcA.transceive(NfcA.java:129)
at com.example.alex.nfcapppce.MainActivity$2.run(MainActivity.java:155)
at java.lang.Thread.run(Thread.java:761)
推荐答案
已解决:
当尝试使用没有保护的标签进行身份验证时，通信只是崩溃而不是抛出适当的异常以进行捕获，因为我没有捕获到异常，因此应用程序继续尝试收发数据，但是标记是丢失"，现在称为异常"正在告诉我.
When trying to authenticate with a tag that does not have a protection yet the communication just crashes instead of throwing a proper Exception to catch, because I am not catching an exception the application continues trying to transceive data, but the tag "was lost" as the now called Exception is telling me.
要知道标签是否已受到保护，请检查Auth0以进行设置保护:
To know if the tag is already protected, check Auth0 for set protection:
byte[] response;
//Read page 41 on NTAG213, will be different for other tags
response = mifare.transceive(new byte[] {
(byte) 0x30, // READ
41 // page address
});
// Authenticate with the tag first
// only if the Auth0 byte is not 0xFF,
// which is the default value meaning unprotected
if(response[3] != (byte)0xFF) {
try {
response = mifare.transceive(new byte[]{
(byte) 0x1B, // PWD_AUTH
pwd[0], pwd[1], pwd[2], pwd[3]
});
// Check if PACK is matching expected PACK
// This is a (not that) secure method to check if tag is genuine
if ((response != null) && (response.length >= 2)) {
final byte[] packResponse = Arrays.copyOf(response, 2);
if (!(pack[0] == packResponse[0] && pack[1] == packResponse[1])) {runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(ctx, "Tag could not be authenticated:\n" + packResponse.toString() + "≠" + pack.toString(), Toast.LENGTH_LONG).show();
}
});
}else{
runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(ctx, "Tag successfully authenticated!", Toast.LENGTH_SHORT).show();
}
});
}
}
} catch (TagLostException e) {
e.printStackTrace();
}
}else{
// Protect tag with your password in case
// it's not protected yet
// Get Page 2Ah
response = mifare.transceive(new byte[] {
(byte) 0x30, // READ
(byte) 0x2A // page address
});
// configure tag as write-protected with unlimited authentication tries
if ((response != null) && (response.length >= 16)) { // read always returns 4 pages
boolean prot = false; // false = PWD_AUTH for write only, true = PWD_AUTH for read and write
int authlim = 0; // 0 = unlimited tries
mifare.transceive(new byte[] {
(byte) 0xA2, // WRITE
(byte) 0x2A, // page address
(byte) ((response[0] & 0x078) | (prot ? 0x080 : 0x000) | (authlim & 0x007)), // set ACCESS byte according to our settings
0, 0, 0 // fill rest as zeros as stated in datasheet (RFUI must be set as 0b)
});
}
// Get page 29h
response = mifare.transceive(new byte[] {
(byte) 0x30, // READ
(byte) 0x29 // page address
});
// Configure tag to protect entire storage (page 0 and above)
if ((response != null) && (response.length >= 16)) { // read always returns 4 pages
int auth0 = 0; // first page to be protected
mifare.transceive(new byte[] {
(byte) 0xA2, // WRITE
(byte) 0x29, // page address
response[0], 0, response[2], // Keep old mirror values and write 0 in RFUI byte as stated in datasheet
(byte) (auth0 & 0x0ff)
});
}
// Send PACK and PWD
// set PACK:
mifare.transceive(new byte[] {
(byte)0xA2,
(byte)0x2C,
pack[0], pack[1], 0, 0 // Write PACK into first 2 Bytes and 0 in RFUI bytes
});
// set PWD:
mifare.transceive(new byte[] {
(byte)0xA2,
(byte)0x2B,
pwd[0], pwd[1], pwd[2], pwd[3] // Write all 4 PWD bytes into Page 43
});
}
这篇关于NfcA.transceive(byte [] data)抛出TagLostException的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
查看全文
