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;}