我正在开发一个关于NFC写作的应用程序。 让我们称它为Writer ...我正在将数据写入NfcV标签。
我想写的字符串是String test = "this is\ta real\ttestcase\tyou tag";
要写数据,我正在使用NfcV的transceive
方法。
所以这是我的作家方法:
public static String bytesToHex(byte[] bytes) {
StringBuilder sb = new StringBuilder(bytes.length * 2);
Formatter formatter = new Formatter(sb);
for (byte b : bytes) {
formatter.format("%02X", b);
}
formatter.close();
return sb.toString();
}
public void write(View v) {
try {
String[] tagInfoArray = new String[tagData.size()];
for (int i = 0; i < tagData.size(); i++)
tagInfoArray[i] = tagData.get(i).getText().toString();
String tagInfo = join(tagInfoArray, "\t");
//String test = "this is\ta real\ttestcase\tyou tag";
writeTag(tag, tagInfo);
} catch (NullPointerException e) {
Toast.makeText(this, "How about providing a tag!",
Toast.LENGTH_LONG).show();
} finally {
write.setBackgroundResource(R.layout.bluebutton);
}
}
public String join(String[] input, String delim) {
String output = "";
if (input.length > 0)
output += input[0];
if (input.length > 1)
for (int i = 1; i < input.length; i++)
output += delim + input[i];
return output;
}
public void exitButton(View v) {
this.foreground.disableForeground();
System.exit(0);
}
public void writeTag(Tag tag, String data) {
NfcV myTag = NfcV.get(tag);
try {
myTag.connect();
if (myTag.isConnected()) {
byte[] info = data.getBytes();
int dataLength = info.length;
if (data.length()/4 <= 64){
byte[] args = new byte[15];
args[0] = 0x20;
args[1] = 0x21;
byte[] id = tag.getId();
for (int o=0; o<8; o++)
args[o+2] = id[o];
for (int i = 0; i<64; i++) {
args[10] = (byte) i;
args[11] = 0x00;
args[12] = 0x00;
args[13] = 0x00;
args[14] = 0x00;
byte[] out = myTag.transceive(args);
String out2 = bytesToHex(out);
System.out.println("1:.. " + printHex(out2));
}
for (int i = 0; i<=dataLength/4; i++) {
args[10] = (byte) i;
args[11] = getByte(info, (i*4)+0);
args[12] = getByte(info, (i*4)+1);
args[13] = getByte(info, (i*4)+2);
args[14] = getByte(info, (i*4)+3);
byte[] out = myTag.transceive(args);
String out2 = bytesToHex(out);
System.out.println("2:.. " + printHex(out2));
}
}
}
} catch (IOException e) {
System.out.println(e.getMessage());
} finally {
if (myTag != null) {
try {
myTag.close();
} catch (IOException e) {
System.out.println(e.getMessage());
}
}
}
}
public static byte getByte(byte[] input, int key){
try {
return input[key];
} catch (Exception e){
return (byte)0x00;
}
}
public String printByte(byte[] input){
try {
return new String(input, "UTF-8");
} catch (UnsupportedEncodingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return "";
}
public String printHex(String input){
return input;
}
因此,当我写东西时,结果并不是我所期待的。它要么根本不写,要么只是写部分,而不是覆盖,之前标记上的内容。
这是输出:
11-05 15:32:33.139: I/System.out(1390): 1:.. 00
11-05 15:32:33.249: I/System.out(1390): 1:.. 00
11-05 15:32:33.349: I/System.out(1390): 1:.. 00
11-05 15:32:33.449: I/System.out(1390): 1:.. 00
11-05 15:32:33.549: I/System.out(1390): 1:.. 00
11-05 15:32:33.649: I/System.out(1390): 1:.. 00
11-05 15:32:33.759: I/System.out(1390): 1:.. 00
11-05 15:32:33.859: I/System.out(1390): 1:.. 00
11-05 15:32:33.959: I/System.out(1390): 1:.. 00
11-05 15:32:34.059: I/System.out(1390): 1:.. 00
11-05 15:32:34.159: I/System.out(1390): 1:.. 00
11-05 15:32:34.259: I/System.out(1390): 1:.. 00
11-05 15:32:34.359: I/System.out(1390): 1:.. 00
11-05 15:32:34.469: I/System.out(1390): 1:.. 00
11-05 15:32:34.569: I/System.out(1390): 1:.. 00
11-05 15:32:34.669: I/System.out(1390): 1:.. 00
11-05 15:32:34.769: I/System.out(1390): 1:.. 00
11-05 15:32:34.869: I/System.out(1390): 1:.. 00
11-05 15:32:34.979: I/System.out(1390): 1:.. 00
11-05 15:32:35.079: I/System.out(1390): 1:.. 00
11-05 15:32:35.179: I/System.out(1390): 1:.. 00
11-05 15:32:35.289: I/System.out(1390): 1:.. 00
11-05 15:32:35.389: I/System.out(1390): 1:.. 00
11-05 15:32:35.489: I/System.out(1390): 1:.. 00
11-05 15:32:35.589: I/System.out(1390): 1:.. 00
11-05 15:32:35.689: I/System.out(1390): 1:.. 00
11-05 15:32:35.789: I/System.out(1390): 1:.. 00
11-05 15:32:35.889: I/System.out(1390): 1:.. 00
11-05 15:32:35.989: I/System.out(1390): Transceive failed
答案 0 :(得分:2)
总结初始帖子中的各种问题:
NfcV.getMaxTransceiveLength()
返回有关一个命令/一个响应中可以交换的最大字节数的信息。它不提供有关标记大小的信息!。Tag.getId()
获取ID并根据标记制造商对其进行解析。数据表)。另一种方法是读取直到第一个IOException并从该信息推断标记大小。您可以稍后重新连接标记以继续读/写。但是,请记住,通信中的任何其他中断(例如,用户未正确扫描标记)也可能导致IOExceptions,并可能因此伪造您的估计标记大小。答案 1 :(得分:1)
对于英飞凌科技不知道,但对于恩智浦ICODE和TI标签(ISO15693)存在Get System Information
命令。我将附加一个带响应字节的图像。在此示例中,块的数量是0x3F + 1. 0x03 + 1是每个块的字节数。所以3f = 63和03 = 3,总内存=(63 + 1)*(3 + 1)= 256字节
我这样使用它(我正在发送一个已命令的命令,命令中包含标记id,但这不是必需的):
nfcV = NfcV.get(tag);
byte[] id = tag.getId();
if (nfcV != null) {
byte[] infoCmd = new byte[2 + id.length];
// set "addressed" flag
infoCmd[0] = 0x20;
// ISO 15693 Get System Information command byte
infoCmd[1] = 0x2B;
//adding the tag id
System.arraycopy(id, 0, infoCmd, 2, id.length);
int memoryBlocks = null;
try {
nfcV.connect();
byte[] data = nfcV.transceive(infoCmd);
memoryBlocks = Integer.parseInt(String.format("%02X", data[data.length-3]), 16);
}
catch (IOException e) {
e.printStackTrace();
}
finally {
try {
nfcV.close();
}
catch (IOException e) {
e.printStackTrace();
}
}