NumberUtil

public final class NumberUtil {
  private final static char[] HEX = { '0', '1', '2', '3', '4', '5', '6', '7',
			'8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };

	private Util() {
	}

	public static byte[] toBytes(int a) {
		return new byte[] { (byte) (0x000000ff & (a >>> 24)),
				(byte) (0x000000ff & (a >>> 16)),
				(byte) (0x000000ff & (a >>> 8)), (byte) (0x000000ff & (a)) };
	}

	public static int toInt(byte[] b, int s, int n) {
		int ret = 0;

		final int e = s + n;
		for (int i = s; i < e; ++i) {
			ret <<= 8;
			ret |= b[i] & 0xFF;
		}
		return ret;
	}

	public static int toIntR(byte[] b, int s, int n) {
		int ret = 0;

		for (int i = s; (i >= 0 && n > 0); --i, --n) {
			ret <<= 8;
			ret |= b[i] & 0xFF;
		}
		return ret;
	}

	public static int toInt(byte... b) {
		int ret = 0;
		for (final byte a : b) {
			ret <<= 8;
			ret |= a & 0xFF;
		}
		return ret;
	}

  //字节转为十六位显示
	public static String toHexString(byte[] d, int s, int n) {
		final char[] ret = new char[n * 2];
		final int e = s + n;

		int x = 0;
		for (int i = s; i < e; ++i) {
			final byte v = d[i];
			ret[x++] = HEX[0x0F & (v >> 4)];
			ret[x++] = HEX[0x0F & v];
		}
		return new String(ret);
	}

	public static String toHexStringR(byte[] d, int s, int n) {
		final char[] ret = new char[n * 2];

		int x = 0;
		for (int i = s + n - 1; i >= s; --i) {
			final byte v = d[i];
			ret[x++] = HEX[0x0F & (v >> 4)];
			ret[x++] = HEX[0x0F & v];
		}
		return new String(ret);
	}

	public static int parseInt(String txt, int radix, int def) {
		int ret;
		try {
			ret = Integer.valueOf(txt, radix);
		} catch (Exception e) {
			ret = def;
		}

		return ret;
	}
	
	public static String toAmountString(float value) {
		return String.format("%.2f", value);
	}
}