byte数组转化为int 以及int转为4个byte

public static int getINTFromByte(byte[] buffer)
	{
		int a = 0;
		a = (0xff000000&(((int)buffer[0])<<24)
		    |0x00ff0000&(((int)buffer[1])<<16)
		    |0x0000ff00&(((int)buffer[2])<<8)
		    |0x000000ff&(((int)buffer[3])<<0));
		return a;
	}


private byte[] getBytesFromInt(int length)
	{
		byte b[] = new byte[4];
		b[0] = (byte)(length>>24 & 0xFF);
		b[1] = (byte)(length>>16 & 0xFF);
		b[2] = (byte)(length>>8 & 0xFF);
		b[3] = (byte)(length>>0 & 0xFF);
		return b;			
	}