code: public String readLine() throws IOException{
          StringBuilder sb = new StringBuilder();
          for(;;){
              int v = peek();
              if(v == '\r' || v == '\n'){
                  poll();
                  v = peekNext();
                  if(v == '\r' || v == '\n'){
                      poll();
                  }
                  break;
              }
              sb.append((char)poll());
          }
          return sb.toString();
      }
docs: 读取一行
  @return 一行数据
  @throws IOException