ByteConvert.java

package com.jerome.utils.format;
import java.util.Arrays;

public class ByteConvert {
	
	public static void main(String[] args) {
		char ch = 'a';
		byte[] bb = new byte[2];
		char2bytes(bb, ch, 0);
		System.out.println(Arrays.toString(bb));
		System.out.println(bytes2char(bb,0));
	}
	// 以下 是整型数 和 网络字节序的 byte[] 数组之间的转换
	public static byte[] longToBytes(long n) {
		byte[] b = new byte[8];
		b[7] = (byte) (n & 0xff);
		b[6] = (byte) (n >> 8 & 0xff);
		b[5] = (byte) (n >> 16 & 0xff);
		b[4] = (byte) (n >> 24 & 0xff);
		b[3] = (byte) (n >> 32 & 0xff);
		b[2] = (byte) (n >> 40 & 0xff);
		b[1] = (byte) (n >> 48 & 0xff);
		b[0] = (byte) (n >> 56 & 0xff);
		return b;
	}

	public static void longToBytes(long n, byte[] array, int offset) {
		array[7 + offset] = (byte) (n & 0xff);
		array[6 + offset] = (byte) (n >> 8 & 0xff);
		array[5 + offset] = (byte) (n >> 16 & 0xff);
		array[4 + offset] = (byte) (n >> 24 & 0xff);
		array[3 + offset] = (byte) (n >> 32 & 0xff);
		array[2 + offset] = (byte) (n >> 40 & 0xff);
		array[1 + offset] = (byte) (n >> 48 & 0xff);
		array[0 + offset] = (byte) (n >> 56 & 0xff);
	}

	public static long bytesToLong(byte[] array) {
		return ((((long) array[0] & 0xff) << 56)
				| (((long) array[1] & 0xff) << 48)
				| (((long) array[2] & 0xff) << 40)
				| (((long) array[3] & 0xff) << 32)
				| (((long) array[4] & 0xff) << 24)
				| (((long) array[5] & 0xff) << 16)
				| (((long) array[6] & 0xff) << 8) | (((long) array[7] & 0xff) << 0));
	}

	public static long bytesToLong(byte[] array, int offset) {
		return ((((long) array[offset + 0] & 0xff) << 56)
				| (((long) array[offset + 1] & 0xff) << 48)
				| (((long) array[offset + 2] & 0xff) << 40)
				| (((long) array[offset + 3] & 0xff) << 32)
				| (((long) array[offset + 4] & 0xff) << 24)
				| (((long) array[offset + 5] & 0xff) << 16)
				| (((long) array[offset + 6] & 0xff) << 8) 
				| (((long) array[offset + 7] & 0xff) << 0));
	}

	public static byte[] intToBytes(int n) {
		byte[] b = new byte[4];
		b[3] = (byte) (n & 0xff);
		b[2] = (byte) (n >> 8 & 0xff);
		b[1] = (byte) (n >> 16 & 0xff);
		b[0] = (byte) (n >> 24 & 0xff);
		return b;
	}

	public static void intToBytes(int n, byte[] array, int offset) {
		array[3 + offset] = (byte) (n & 0xff);
		array[2 + offset] = (byte) (n >> 8 & 0xff);
		array[1 + offset] = (byte) (n >> 16 & 0xff);
		array[offset] = (byte) (n >> 24 & 0xff);
	}

	public static int bytesToInt(byte b[]) {
		return b[3] & 0xff | (b[2] & 0xff) << 8 | (b[1] & 0xff) << 16
				| (b[0] & 0xff) << 24;
	}

	public static int bytesToInt(byte b[], int offset) {
		return b[offset + 3] & 0xff | (b[offset + 2] & 0xff) << 8
				| (b[offset + 1] & 0xff) << 16 | (b[offset] & 0xff) << 24;
	}

	public static byte[] uintToBytes(long n) {
		byte[] b = new byte[4];
		b[3] = (byte) (n & 0xff);
		b[2] = (byte) (n >> 8 & 0xff);
		b[1] = (byte) (n >> 16 & 0xff);
		b[0] = (byte) (n >> 24 & 0xff);

		return b;
	}

	public static void uintToBytes(long n, byte[] array, int offset) {
		array[3 + offset] = (byte) (n);
		array[2 + offset] = (byte) (n >> 8 & 0xff);
		array[1 + offset] = (byte) (n >> 16 & 0xff);
		array[offset] = (byte) (n >> 24 & 0xff);
	}

	public static long bytesToUint(byte[] array) {
		return ((long) (array[3] & 0xff)) | ((long) (array[2] & 0xff)) << 8
				| ((long) (array[1] & 0xff)) << 16
				| ((long) (array[0] & 0xff)) << 24;
	}

	public static long bytesToUint(byte[] array, int offset) {
		return ((long) (array[offset + 3] & 0xff))
				| ((long) (array[offset + 2] & 0xff)) << 8
				| ((long) (array[offset + 1] & 0xff)) << 16
				| ((long) (array[offset] & 0xff)) << 24;
	}

	public static byte[] shortToBytes(short n) {
		byte[] b = new byte[2];
		b[1] = (byte) (n & 0xff);
		b[0] = (byte) ((n >> 8) & 0xff);
		return b;
	}

	public static void shortToBytes(short n, byte[] array, int offset) {
		array[offset + 1] = (byte) (n & 0xff);
		array[offset] = (byte) ((n >> 8) & 0xff);
	}

	public static short bytesToShort(byte[] b) {
		return (short) (b[1] & 0xff | (b[0] & 0xff) << 8);
	}

	public static short bytesToShort(byte[] b, int offset) {
		return (short) (b[offset + 1] & 0xff | (b[offset] & 0xff) << 8);
	}

	public static byte[] ushortToBytes(int n) {
		byte[] b = new byte[2];
		b[1] = (byte) (n & 0xff);
		b[0] = (byte) ((n >> 8) & 0xff);
		return b;
	}

	public static void ushortToBytes(int n, byte[] array, int offset) {
		array[offset + 1] = (byte) (n & 0xff);
		array[offset] = (byte) ((n >> 8) & 0xff);
	}

	public static int bytesToUshort(byte b[]) {
		return b[1] & 0xff | (b[0] & 0xff) << 8;
	}

	public static int bytesToUshort(byte b[], int offset) {
		return b[offset + 1] & 0xff | (b[offset] & 0xff) << 8;
	}

	public static byte[] ubyteToBytes(int n) {
		byte[] b = new byte[1];
		b[0] = (byte) (n & 0xff);
		return b;
	}

	public static void ubyteToBytes(int n, byte[] array, int offset) {
		array[0] = (byte) (n & 0xff);
	}

	public static int bytesToUbyte(byte array) {
		return array & 0xff;
	}

	public static int bytesToUbyte(byte[] array, int offset) {
		return array[offset] & 0xff;
	}

	/**
	 * 字符到字节转换
	 * 
	 * @param ch
	 * @return
	 */
	public static void char2bytes(byte[] bb, char ch, int index) {
		int temp = (int) ch;
		for (int i = 0; i < 2; i++) {
			// 将最高位保存在最低位
			bb[index + i] = new Integer(temp & 0xff).byteValue();
			temp = temp >> 8; // 向右移8位
		}
	}

	/**
	 * 字节到字符转换
	 * 
	 * @param b
	 * @return
	 */
	public static char bytes2char(byte[] b, int index) {
		int s = 0;
		if (b[index + 1] > 0)
			s += b[index + 1];
		else
			s += 256 + b[index + 0];
		s *= 256;
		if (b[index + 0] > 0)
			s += b[index + 1];
		else
			s += 256 + b[index + 0];
		char ch = (char) s;
		return ch;
	}

	/**
	 * float转换byte
	 * 
	 * @param bb
	 * @param x
	 * @param index
	 */
	public static void putFloat(byte[] bb, float x, int index) {
		// byte[] b = new byte[4];
		int l = Float.floatToIntBits(x);
		for (int i = 0; i < 4; i++) {
			bb[index + i] = new Integer(l).byteValue();
			l = l >> 8;
		}
	}

	/**
	 * 通过byte数组取得float
	 * 
	 * @param bb
	 * @param index
	 * @return
	 */
	public static float getFloat(byte[] b, int index) {
		int l;
		l = b[index + 0];
		l &= 0xff;
		l |= ((long) b[index + 1] << 8);
		l &= 0xffff;
		l |= ((long) b[index + 2] << 16);
		l &= 0xffffff;
		l |= ((long) b[index + 3] << 24);
		return Float.intBitsToFloat(l);
	}

	/**
	 * double转换byte
	 * 
	 * @param bb
	 * @param x
	 * @param index
	 */
	public static void putDouble(byte[] bb, double x, int index) {
		// byte[] b = new byte[8];
		long l = Double.doubleToLongBits(x);
		for (int i = 0; i < 4; i++) {
			bb[index + i] = new Long(l).byteValue();
			l = l >> 8;
		}
	}

	/**
	 * 通过byte数组取得float
	 * 
	 * @param bb
	 * @param index
	 * @return
	 */
	public static double getDouble(byte[] b, int index) {
		long l;
		l = b[0];
		l &= 0xff;
		l |= ((long) b[1] << 8);
		l &= 0xffff;
		l |= ((long) b[2] << 16);
		l &= 0xffffff;
		l |= ((long) b[3] << 24);
		l &= 0xffffffffl;
		l |= ((long) b[4] << 32);
		l &= 0xffffffffffl;
		l |= ((long) b[5] << 40);
		l &= 0xffffffffffffl;
		l |= ((long) b[6] << 48);
		l &= 0xffffffffffffffl;
		l |= ((long) b[7] << 56);
		return Double.longBitsToDouble(l);
	}
}