conocer_tipo_archivo.java

private String getMimeFromByte(byte[] src) {
        
  if (src[0] == 0x25 && src[1] == 0x50 && src[2] == 0x44 && src[3] == 0x46) {
      return "application/pdf";
  }
  if (src[0] == 0x50 && src[1] == 0x4b) {
      return "application/zip";
  }
  if (src[0] == 0xd0 && src[1] == 0xcf && src[2] == 0x11 && src[3] == 0xe0 && src[4] == 0xa1 && src[5] == 0xb1 && src[6] == 0x1a && src[7] == 0xe1) {
      return "application/vnd.ms-powerpoint";
  }
    return "application/octet-stream";
}