老物，java的int、char、long、float、double对byte的变换，在通信的时候会用到

老物，java的int、char、long、float、double对byte的转换，在通信的时候会用到

package com.util;

/**
 * 
 * <ul>
 * <li>文件名称: com.born.util.ByteUtil.java</li>
 * <li>文件描述: byte转换工具</li>
 * <li>版权所有: 版权所有(C)2001-2006</li>
 * <li>公 司: bran</li>
 * <li>内容摘要:</li>
 * <li>其他说明:</li>
 * <li>完成日期：2011-7-18</li>
 * <li>修改记录0：无</li>
 * </ul>
 * 
 * @version 1.0
 * @author 许力多
 */
public class ByteUtil {
	/**
	 * 转换short为byte
	 * 
	 * @param b
	 * @param s
	 *            需要转换的short
	 * @param index
	 */
	public static void putShort(byte b[], short s, int index) {
		b[index + 1] = (byte) (s >> 8);
		b[index + 0] = (byte) (s >> 0);
	}

	/**
	 * 通过byte数组取到short
	 * 
	 * @param b
	 * @param index
	 *            第几位开始取
	 * @return
	 */
	public static short getShort(byte[] b, int index) {
		return (short) (((b[index + 1] << 8) | b[index + 0] & 0xff));
	}

	/**
	 * 转换int为byte数组
	 * 
	 * @param bb
	 * @param x
	 * @param index
	 */
	public static void putInt(byte[] bb, int x, int index) {
		bb[index + 3] = (byte) (x >> 24);
		bb[index + 2] = (byte) (x >> 16);
		bb[index + 1] = (byte) (x >> 8);
		bb[index + 0] = (byte) (x >> 0);
	}

	/**
	 * 通过byte数组取到int
	 * 
	 * @param bb
	 * @param index
	 *            第几位开始
	 * @return
	 */
	public static int getInt(byte[] bb, int index) {
		return (int) ((((bb[index + 3] & 0xff) << 24)
				| ((bb[index + 2] & 0xff) << 16)
				| ((bb[index + 1] & 0xff) << 8) | ((bb[index + 0] & 0xff) << 0)));
	}

	/**
	 * 转换long型为byte数组
	 * 
	 * @param bb
	 * @param x
	 * @param index
	 */
	public static void putLong(byte[] bb, long x, int index) {
		bb[index + 7] = (byte) (x >> 56);
		bb[index + 6] = (byte) (x >> 48);
		bb[index + 5] = (byte) (x >> 40);
		bb[index + 4] = (byte) (x >> 32);
		bb[index + 3] = (byte) (x >> 24);
		bb[index + 2] = (byte) (x >> 16);
		bb[index + 1] = (byte) (x >> 8);
		bb[index + 0] = (byte) (x >> 0);
	}

	/**
	 * 通过byte数组取到long
	 * 
	 * @param bb
	 * @param index
	 * @return
	 */
	public static long getLong(byte[] bb, int index) {
		return ((((long) bb[index + 7] & 0xff) << 56)
				| (((long) bb[index + 6] & 0xff) << 48)
				| (((long) bb[index + 5] & 0xff) << 40)
				| (((long) bb[index + 4] & 0xff) << 32)
				| (((long) bb[index + 3] & 0xff) << 24)
				| (((long) bb[index + 2] & 0xff) << 16)
				| (((long) bb[index + 1] & 0xff) << 8) | (((long) bb[index + 0] & 0xff) << 0));
	}

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

	/**
	 * 字节到字符转换
	 * 
	 * @param b
	 * @return
	 */
	public static char getChar(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 < 8; i++) {
			bb[index + i] = new Long(l).byteValue();
			l = l >> 8;
		}
	}

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