字节处理工具类，可以从byte[]数组中读取Int16，Int32，Int64，以及int或long与byte[]数组的相互转换。
package com.itshidu.util;
/**
- 位处理，字节处理
@author Master.Xia Date:2017年12月15日
*/
public class BitConverter {public static short ToInt16(byte[] bytes, int offset) {
short result = (short) ((int)bytes[offset]&0xff); result |= ((int)bytes[offset+1]&0xff) << 8; return (short) (result & 0xffff);}
public static int ToUInt16(byte[] bytes, int offset) {int result = (int)bytes[offset+1]&0xff; result |= ((int)bytes[offset]&0xff) << 8; return result & 0xffff;}
public static int ToInt32(byte[] bytes, int offset) {int result = (int)bytes[offset]&0xff; result |= ((int)bytes[offset+1]&0xff) << 8; result |= ((int)bytes[offset+2]&0xff) << 16; result |= ((int)bytes[offset+3]&0xff) << 24; return result;}
public static long ToUInt32(byte[] bytes, int offset) {long result = (int)bytes[offset]&0xff; result |= ((int)bytes[offset+1]&0xff) << 8; result |= ((int)bytes[offset+2]&0xff) << 16; result |= ((int)bytes[offset+3]&0xff) << 24; return result & 0xFFFFFFFFL;}
public static long ToInt64(byte[] buffer,int offset) {long values = 0; for (int i = 0; i < 8; i++) { values <<= 8; values |= (buffer[offset+i] & 0xFF); } return values;}
public static long ToUInt64(byte[] bytes, int offset) {long result = 0; for (int i = 0; i <= 56; i += 8) { result |= ((int)bytes[offset++]&0xff) << i; } return result;}
public static float ToFloat(byte[] bs, int index) {return Float.intBitsToFloat(ToInt32(bs, index));}
public static double ToDouble(byte[] arr,int offset) {return Double.longBitsToDouble(ToUInt64(arr, offset));}
public static boolean ToBoolean(byte[] bytes,int offset) {return (bytes[offset]==0x00)? false:true;}
public static byte[] GetBytes(short value) {
byte[] bytes = new byte[2]; bytes[0] = (byte) (value & 0xff); bytes[1] = (byte) ((value & 0xff00) >> 8); return bytes;}
public static byte[] GetBytes(int value) {byte[] bytes = new byte[4]; bytes[0] = (byte) ((value)&0xFF); //最低位 bytes[1] = (byte) ((value >> 8)&0xFF); bytes[2] = (byte) ((value >> 16)&0xFF); bytes[3] = (byte) ((value >>> 24)); //最高位，无符号右移 return bytes;}
public static byte[] GetBytes(long values) {byte[] buffer = new byte[8]; for (int i = 0; i < 8; i++) { int offset = 64 - (i + 1) * 8; buffer[i] = (byte)((values >> offset) & 0xff); } return buffer;}
public static byte[] GetBytes(float value) {return GetBytes(Float.floatToIntBits(value));}
public static byte[] GetBytes(double val) {long value = Double.doubleToLongBits(val); return GetBytes(value);}
public static byte[] GetBytes(boolean value) {return new byte[]{(byte)(value? 1:0)};}
public static byte IntToByte(int x) {
return (byte) x;}
public static int ByteToInt(byte b) {return b & 0xFF;}
public static char ToChar(byte[] bs,int offset) {return (char) (((bs[offset] & 0xFF) << 8) | (bs[offset+1] & 0xFF));}
public static byte[] GetBytes(char value) {byte[] b = new byte[2]; b[0] = (byte) ((value & 0xFF00) >> 8); b[1] = (byte) (value & 0xFF); return b;}
public static byte[] Concat(byte[]... bs) {
int len = 0,idx=0; for(byte[] b:bs)len+=b.length; byte[] buffer = new byte[len]; for(byte[] b:bs) { System.arraycopy(b,0, buffer, idx, b.length); idx+=b.length; } return buffer;}
public static void main(String[] args) {long a = 123456; byte[] b1=GetBytes(a); long b= ToInt64(b1, 0); System.out.println(b);}
}
