[英]how do you read the unique ID of an NFC tag on android?
Tag myTag = (Tag) intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
Log.i("tag ID", myTag.getId().toString());
這給了我一個像“[B@40521c40”這樣的 ID,但這個 ID 每次讀取都會改變。
任何幫助將不勝感激。
謝謝。
您仍然需要將字節轉換為字符串:
private String bytesToHexString(byte[] src) {
StringBuilder stringBuilder = new StringBuilder("0x");
if (src == null || src.length <= 0) {
return null;
}
char[] buffer = new char[2];
for (int i = 0; i < src.length; i++) {
buffer[0] = Character.forDigit((src[i] >>> 4) & 0x0F, 16);
buffer[1] = Character.forDigit(src[i] & 0x0F, 16);
System.out.println(buffer);
stringBuilder.append(buffer);
}
return stringBuilder.toString();
}
我遇到了類似的問題並且可以解決它。 問題是轉換為字符串。
myTag.getId() 返回字節數組。 您應該將這些字節轉換為十六進制字符串。 我使用了在 stackoverflow.com 中找到的以下函數
final protected static char[] hexArray = {'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};
public static String bytesToHex(byte[] bytes) {
char[] hexChars = new char[bytes.length * 2];
int v;
for ( int j = 0; j < bytes.length; j++ ) {
v = bytes[j] & 0xFF;
hexChars[j * 2] = hexArray[v >>> 4];
hexChars[j * 2 + 1] = hexArray[v & 0x0F];
}
return new String(hexChars);
}
我通過將字節數組 ID 傳遞給以下函數解決了這個問題:
private fun ByteArrayToHexString(inarray: ByteArray): String? {
var i: Int
var j: Int
var `in`: Int
val hex = arrayOf(
"0",
"1",
"2",
"3",
"4",
"5",
"6",
"7",
"8",
"9",
"A",
"B",
"C",
"D",
"E",
"F"
)
var out = ""
j = 0
while (j < inarray.size) {
`in` = inarray[j].toInt() and 0xff
i = `in` shr 4 and 0x0f
out += hex[i]
i = `in` and 0x0f
out += hex[i]
++j
}
return out
}
這個函數在java中的來源: https : //gist.github.com/luixal/5768921
public String getHexValue(final byte[] buffer) {
if (buffer == null || buffer.length == 0) {
return ("0x" + "[none]");
}
final StringBuffer sb = new StringBuffer();
sb.append("0x");
for (int i = 0; i < buffer.length - 1; i++) {
sb.append(String.format("%02X%s", buffer[i], ""));
}
sb.append(String.format("%02X", buffer[buffer.length - 1]));
return sb.toString();
}
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