code: public static int charLength(CharSequence str) {
          int clength = 0;
          for (int i = 0; i < str.length(); i++) {
              clength += isFullWidthCharacter(str.charAt(i)) ? 2 : 1;
          }
          return clength;
      }
docs: 计算字符串的字符长度(全角算2, 半角算1)
  
  @param str
  被计算的字符串
  @return 字符串的字符长度