code: public void write(byte value) {
          if (count >= content.length - 1) {
              byte[] ns = new byte[content.length + 8];
              System.arraycopy(content, 0, ns, 0, count);
              this.content = ns;
          }
          content[count++] = value;
      }
docs: 写入一个byte值
  
  @param value byte值