Java中byte与short、int、long互相转换的方法分享

实现思路:
    直接使用位移的方式
	即可实现这些不同数据类型之间的转换

/**
 * 将int转为高字节在前，低字节在后的byte数组（大端）
 * @param n int
 * @return byte[]
 */
public static byte[] intToByteBig(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;
}

 /**
  * 将int转为低字节在前，高字节在后的byte数组（小端）
  * @param n int
  * @return byte[]
  */
public static byte[] intToByteLittle(int n) {
	byte[] b = new byte[4];
	b[0] = (byte) (n & 0xff);
	b[1] = (byte) (n >> 8 & 0xff);
	b[2] = (byte) (n >> 16 & 0xff);
	b[3] = (byte) (n >> 24 & 0xff);
	return b;
}

/**
 * byte数组到int的转换(小端)
 * @param bytes
 * @return
 */
public static int bytes2IntLittle(byte[] bytes )
{
	int int1=bytes[0]&0xff;
	int int2=(bytes[1]&0xff)<<8;
	int int3=(bytes[2]&0xff)<<16;
	int int4=(bytes[3]&0xff)<<24;

	return int1|int2|int3|int4;
}

/**
 * byte数组到int的转换(大端)
 * @param bytes
 * @return
 */
public static int bytes2IntBig(byte[] bytes )
{
	int int1=bytes[3]&0xff;
	int int2=(bytes[2]&0xff)<<8;
	int int3=(bytes[1]&0xff)<<16;
	int int4=(bytes[0]&0xff)<<24;

	return int1|int2|int3|int4;
}

/**
 * 将short转为高字节在前，低字节在后的byte数组（大端）
 * @param n short
 * @return byte[]
 */
public static byte[] shortToByteBig(short n) {
	byte[] b = new byte[2];
	b[1] = (byte) (n & 0xff);
	b[0] = (byte) (n >> 8 & 0xff);
	return b;
}

/**
 * 将short转为低字节在前，高字节在后的byte数组(小端)
 * @param n short
 * @return byte[]
 */
public static byte[] shortToByteLittle(short n) {
	byte[] b = new byte[2];
	b[0] = (byte) (n & 0xff);
	b[1] = (byte) (n >> 8 & 0xff);
	return b;
}

/**
 *  读取小端byte数组为short
 * @param b
 * @return
 */
public static short byteToShortLittle(byte[] b) {
	return (short) (((b[1] << 8) | b[0] & 0xff));
}

/**
 *  读取大端byte数组为short
 * @param b
 * @return
 */
public static short byteToShortBig(byte[] b) {
	return (short) (((b[0] << 8) | b[1] & 0xff));
}

/**
 * long类型转byte[] (大端)
 * @param n
 * @return
 */
public static byte[] longToBytesBig(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;
}

/**
 * long类型转byte[] (小端)
 * @param n
 * @return
 */
public static byte[] longToBytesLittle(long n) {
	byte[] b = new byte[8];
	b[0] = (byte) (n & 0xff);
	b[1] = (byte) (n >> 8  & 0xff);
	b[2] = (byte) (n >> 16 & 0xff);
	b[3] = (byte) (n >> 24 & 0xff);
	b[4] = (byte) (n >> 32 & 0xff);
	b[5] = (byte) (n >> 40 & 0xff);
	b[6] = (byte) (n >> 48 & 0xff);
	b[7] = (byte) (n >> 56 & 0xff);
	return b;
}

/**
 * byte[]转long类型(小端)
 * @param array
 * @return
 */
public static long bytesToLongLittle( byte[] array )
{
	return ((((long) array[ 0] & 0xff) << 0)
			| (((long) array[ 1] & 0xff) << 8)
			| (((long) array[ 2] & 0xff) << 16)
			| (((long) array[ 3] & 0xff) << 24)
			| (((long) array[ 4] & 0xff) << 32)
			| (((long) array[ 5] & 0xff) << 40)
			| (((long) array[ 6] & 0xff) << 48)
			| (((long) array[ 7] & 0xff) << 56));
}

/**
 * byte[]转long类型(大端)
 * @param array
 * @return
 */
public static long bytesToLongBig( 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));
}