java 16进制Util转换类
《代码来自c3p0》
import java.io.StringReader;
import java.io.StringWriter;
import java.io.IOException;
public final class ByteUtils {
public final static short UNSIGNED_MAX_VALUE = (Byte.MAX_VALUE * 2) + 1;
public static short toUnsigned(byte b) {
return (short) (b < 0 ? (UNSIGNED_MAX_VALUE + 1) + b : b);
}
public static String toHexAscii(byte b) {
StringWriter sw = new StringWriter(2);
addHexAscii(b, sw);
return sw.toString();
}
public static String toHexAscii(byte[] bytes) {
int len = bytes.length;
StringWriter sw = new StringWriter(len * 2);
for (int i = 0; i < len; ++i)
addHexAscii(bytes[i], sw);
return sw.toString();
}
public static byte[] fromHexAscii(String s) throws NumberFormatException {
try {
int len = s.length();
if ((len % 2) != 0)
throw new NumberFormatException("Hex ascii must be exactly two digits per byte.");
int out_len = len / 2;
byte[] out = new byte[out_len];
int i = 0;
StringReader sr = new StringReader(s);
while (i < out_len) {
int val = (16 * fromHexDigit(sr.read())) + fromHexDigit(sr.read());
out[i++] = (byte) val;
}
return out;
} catch (IOException e) {
throw new InternalError("IOException reading from StringReader?!?!");
}
}
static void addHexAscii(byte b, StringWriter sw) {
short ub = toUnsigned(b);
int h1 = ub / 16;
int h2 = ub % 16;
sw.write(toHexDigit(h1));
sw.write(toHexDigit(h2));
}
private static int fromHexDigit(int c) throws NumberFormatException {
if (c >= 0x30 && c < 0x3A)
return c - 0x30;
else if (c >= 0x41 && c < 0x47)
return c - 0x37;
else if (c >= 0x61 && c < 0x67)
return c - 0x57;
else
throw new NumberFormatException('\'' + c + "' is not a valid hexadecimal digit.");
}
private static char toHexDigit(int h) {
char out;
if (h <= 9)
out = (char) (h + 0x30);
else
out = (char) (h + 0x37);
// System.err.println(h + ": " + out);
return out;
}
private ByteUtils() {
}
}