/** * java的int、char、long、float、double對byte的轉換，在通信的時候會用到 * <ul> * <li>文件名稱: com.born.util.ByteUtil.java</li> * <li>文件描述: byte轉換工具</li> * <li>版權所有: 版權所有(C)2001-2006</li> * <li>公 司: bran</li> * <li>內容摘要:</li> * <li>其他說明:</li> * <li>完成日期：2011-7-18</li> * <li>修改記錄0：無</li> * </ul> * * @version 1.0 * @author 許力多 */ public class ByteUtil { /** * 轉換short為byte * * @param b * @param s * 需要轉換的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); } /** * 通過byte數組取到short * * @param b * @param index * 第幾位開始取 * @return */ public static short getShort(byte[] b, int index) { return (short) (((b[index + 1] << 8) | b[index + 0] & 0xff)); } /** * 轉換int為byte數組 * * @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); } /** * 通過byte數組取到int * * @param bb * @param index * 第幾位開始 * @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))); } /** * 轉換long型為byte數組 * * @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); } /** * 通過byte數組取到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)); } /** * 字符到字節轉換 * * @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(); // 將最高位保存在最低位 temp = temp >> 8; // 向右移8位 } } /** * 字節到字符轉換 * * @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轉換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; } } /** * 通過byte數組取得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轉換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; } } /** * 通過byte數組取得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); } }

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