Cách đơn giản
public static String getHexString(byte[] b) throws Exception {
String result = "";
for (int i=0; i < b.length; i++) {
result +=
Integer.toString( ( b[i] & 0xff ) + 0x100, 16).substring( 1 );
}
return result;
}
Cách nhanh hơn:
import java.io.UnsupportedEncodingException;
public class StringUtils {
static final byte[] HEX_CHAR_TABLE = {
(byte)'0', (byte)'1', (byte)'2', (byte)'3',
(byte)'4', (byte)'5', (byte)'6', (byte)'7',
(byte)'8', (byte)'9', (byte)'a', (byte)'b',
(byte)'c', (byte)'d', (byte)'e', (byte)'f'
};
private StringUtils () {}
public static String getHexString(byte[] raw)
throws UnsupportedEncodingException
{
byte[] hex = new byte[2 * raw.length];
int index = 0;
for (byte b : raw) {
int v = b & 0xFF;
hex[index++] = HEX_CHAR_TABLE[v >>> 4];
hex[index++] = HEX_CHAR_TABLE[v & 0xF];
}
return new String(hex, "ASCII");
}
public static void main(String args[]) throws Exception{
byte[] byteArray = {
(byte)255, (byte)254, (byte)253,
(byte)252, (byte)251, (byte)250
};
System.out.println(StringUtils.getHexString(byteArray));
/*
* output :
* fffefdfcfbfa
*/
}
}
Được hơn:
static final String HEXES = "0123456789ABCDEF";
public static String getHex( byte [] raw ) {
if ( raw == null ) {
return null;
}
final StringBuilder hex = new StringBuilder( 2 * raw.length );
for ( final byte b : raw ) {
hex.append(HEXES.charAt((b & 0xF0) >> 4))
.append(HEXES.charAt((b & 0x0F)));
}
return hex.toString();
}