code: public static String[] splitByLength(String str, int len) {
  		int partCount = str.length() / len;
  		int lastPartCount = str.length() % len;
  		int fixPart = 0;
  		if (lastPartCount != 0) {
  			fixPart = 1;
  		}
  
  		final String[] strs = new String[partCount + fixPart];
  		for (int i = 0; i < partCount + fixPart; i++) {
  			if (i == partCount + fixPart - 1 && lastPartCount != 0) {
  				strs[i] = str.substring(i * len, i * len + lastPartCount);
  			} else {
  				strs[i] = str.substring(i * len, i * len + len);
  			}
  		}
  		return strs;
  	}
docs: 根据给定长度，将给定字符串截取为多个部分
  
  @param str 字符串
  @param len 每一个小节的长度
  @return 截取后的字符串数组