java的int、char、long、float、double对byte的转换

【原文地址】http://xuliduo.iteye.com/blog/1126957

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];elses += 256 + b[index + 0];s *= 256;if (b[index + 0] > 0)s += b[index + 1];elses += 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);}}