JAVA byte[], int, long三者之间的相互转换代码

public final static byte[] getBytes(short s, boolean asc) {
    byte[] buf = new byte[2];
    if (asc)
      for (int i = buf.length - 1; i >= 0; i--) {
        buf[i] = (byte) (s & 0x00ff);
        s >>= 8;
      }
    else
      for (int i = 0; i < buf.length; i++) {
        buf[i] = (byte) (s & 0x00ff);
        s >>= 8;
      }
    return buf;
  }
  public final static byte[] getBytes(int s, boolean asc) {
    byte[] buf = new byte[4];
    if (asc)
      for (int i = buf.length - 1; i >= 0; i--) {
        buf[i] = (byte) (s & 0x000000ff);
        s >>= 8;
      }
    else
      for (int i = 0; i < buf.length; i++) {
        buf[i] = (byte) (s & 0x000000ff);
        s >>= 8;
      }
    return buf;
  }
  public final static byte[] getBytes(long s, boolean asc) {
    byte[] buf = new byte[8];
    if (asc)
      for (int i = buf.length - 1; i >= 0; i--) {
        buf[i] = (byte) (s & 0x00000000000000ff);
        s >>= 8;
      }
    else
      for (int i = 0; i < buf.length; i++) {
        buf[i] = (byte) (s & 0x00000000000000ff);
        s >>= 8;
      }
    return buf;
  }
  public final static short getShort(byte[] buf, boolean asc) {
    if (buf == null) {
      throw new IllegalArgumentException("byte array is null!");
    }
    if (buf.length > 2) {
      throw new IllegalArgumentException("byte array size > 2 !");
    }
    short r = 0;
    if (asc)
      for (int i = buf.length - 1; i >= 0; i--) {
        r <<= 8;
        r |= (buf[i] & 0x00ff);
      }
    else
      for (int i = 0; i < buf.length; i++) {
        r <<= 8;
        r |= (buf[i] & 0x00ff);
      }
    return r;
  }
  public final static int getInt(byte[] buf, boolean asc) {
    if (buf == null) {
      throw new IllegalArgumentException("byte array is null!");
    }
    if (buf.length > 4) {
      throw new IllegalArgumentException("byte array size > 4 !");
    }
    int r = 0;
    if (asc)
      for (int i = buf.length - 1; i >= 0; i--) {
        r <<= 8;
        r |= (buf[i] & 0x000000ff);
      }
    else
      for (int i = 0; i < buf.length; i++) {
        r <<= 8;
        r |= (buf[i] & 0x000000ff);
      }
    return r;
  }
  public final static long getLong(byte[] buf, boolean asc) {
    if (buf == null) {
      throw new IllegalArgumentException("byte array is null!");
    }
    if (buf.length > 8) {
      throw new IllegalArgumentException("byte array size > 8 !");
    }
    long r = 0;
    if (asc)
      for (int i = buf.length - 1; i >= 0; i--) {
        r <<= 8;
        r |= (buf[i] & 0x00000000000000ff);
      }
    else
      for (int i = 0; i < buf.length; i++) {
        r <<= 8;
        r |= (buf[i] & 0x00000000000000ff);
      }
    return r;
  }