code: public static String join(final String[] seq, final String delimiter) {
      if (null == seq || seq.length < 1) return "";
      Assert.notNull(delimiter);
      StringBuilder aim = new StringBuilder();
      for (int i = 0; i < seq.length; i++) {
        if (aim.length() > 0) aim.append(delimiter);
        aim.append(seq[i]);
      }
      return aim.toString();
    }
docs: 将数组中的字符串，用delimiter串接起来.<br>
  首尾不加delimiter
  
  @param seq an array of {@link java.lang.String} objects.
  @param delimiter a {@link java.lang.String} object.
  @return a {@link java.lang.String} object.