code: @Override
      public int readInt() {
          final char[] text0 = this.text;
          final int eof = this.limit;
          int currpos = this.position;
          char firstchar = text0[++currpos];
          if (firstchar <= ' ') {
              for (;;) {
                  firstchar = text0[++currpos];
                  if (firstchar > ' ') break;
              }
          }
          boolean quote = false;
          if (firstchar == '"' || firstchar == '\'') {
              quote = true;
              firstchar = text0[++currpos];
              if (firstchar <= ' ') {
                  for (;;) {
                      firstchar = text0[++currpos];
                      if (firstchar > ' ') break;
                  }
              }
              if (firstchar == '"' || firstchar == '\'') {
                  this.position = currpos;
                  return 0;
              }
          }
          int value = 0;
          final boolean negative = firstchar == '-';
          if (!negative) {
              if (firstchar < '0' || firstchar > '9') throw new ConvertException("illegal escape(" + firstchar + ") (position = " + currpos + ") in (" + new String(this.text) + ")");
              value = firstchar - '0';
          }
          for (;;) {
              if (currpos == eof) break;
              char ch = text0[++currpos];
              int val = digits[ch];
              if (quote && val == -3) continue;
              if (val <= -3) break;
              if (val == -1) throw new ConvertException("illegal escape(" + ch + ") (position = " + currpos + ") but '" + ch + "' in (" + new String(this.text) + ")");
              if (val != -2) value = value * 10 + val;
          }
          this.position = currpos - 1;
          return negative ? -value : value;
      }
docs: 读取一个int值
  
  @return int值