code: public static String getFileName(String filePath) {
          if (StringUtils.isEmpty(filePath)) {
              return filePath;
          }
  
          int filePosi = filePath.lastIndexOf(File.separator);
          return (filePosi == -1) ? filePath : filePath.substring(filePosi + 1);
      }
docs: get file name from path, include suffix
  <p/>
  <pre>
  getFileName(null)               =   null
  getFileName("")                 =   ""
  getFileName("   ")              =   "   "
  getFileName("a.mp3")            =   "a.mp3"
  getFileName("a.b.rmvb")         =   "a.b.rmvb"
  getFileName("abc")              =   "abc"
  getFileName("c:\\")              =   ""
  getFileName("c:\\a")             =   "a"
  getFileName("c:\\a.b")           =   "a.b"
  getFileName("c:a.txt\\a")        =   "a"
  getFileName("/home/admin")      =   "admin"
  getFileName("/home/admin/a.txt/b.mp3")  =   "b.mp3"
  </pre>
  
  @param filePath
  @return file name from path, include suffix