`UploadFile` 支持以下 `async` 方法，（使用内部 `SpooledTemporaryFile`）可调用相应的文件方法。

* `write(data)`：把 `data` （`str` 或 `bytes`）写入文件；
* `read(size)`：按指定数量的字节或字符（`size` (`int`)）读取文件内容；
* `seek(offset)`：移动至文件 `offset` （`int`）字节处的位置；
    * 例如，`await myfile.seek(0) ` 移动到文件开头；
    * 执行 `await myfile.read()` 后，需再次读取已读取内容时，这种方法特别好用；
* `close()`：关闭文件。

因为上述方法都是 `async` 方法，要搭配「await」使用。

例如，在 `async` *路径操作函数* 内，要用以下方式读取文件内容：

            this.responseFields = responseFields;
            return this;
        }

        public SearchConditionBuilder offset(final int offset) {
            this.offset = offset;
            return this;
        }

        public SearchConditionBuilder size(final int size) {
            this.size = size;
            return this;
        }

    }


    /**
     * 
     * @param str
     * @param offset
     * @return string length
     */
    public int stringWireLength ( String str, int offset ) {
        int len = str.length() + 1;
        if ( this.useUnicode ) {
            len = str.length() * 2 + 2;
            len = ( offset % 2 ) != 0 ? len + 1 : len;
        }
        return len;
    }

                                        </div>
                                    </div>
                                    <div class="form-group row">
                                        <div class="offset-sm-2 col-sm-10">
                                            <button type="submit" class="btn btn-primary" id="submit"
                                                    name="search"

   * the line and the line separator itself are passed to the abstract {@link #handleLine} method.
   *
   * @param cbuf the character buffer to process
   * @param off the offset into the buffer
   * @param len the number of characters to process
   * @throws IOException if an I/O error occurs
   * @see #finish
   */
  protected void add(char[] cbuf, int off, int len) throws IOException {

  /**
   * Puts a chunk of an array of bytes into this sink. {@code bytes[off]} is the first byte written,
   * {@code bytes[off + len - 1]} is the last.
   *
   * @param bytes a byte array
   * @param off the start offset in the array
   * @param len the number of bytes to write
   * @return this instance
   * @throws IndexOutOfBoundsException if {@code off < 0} or {@code off + len > bytes.length} or
   *     {@code len < 0}
   */

   * the line and the line separator itself are passed to the abstract {@link #handleLine} method.
   *
   * @param cbuf the character buffer to process
   * @param off the offset into the buffer
   * @param len the number of characters to process
   * @throws IOException if an I/O error occurs
   * @see #finish
   */
  protected void add(char[] cbuf, int off, int len) throws IOException {

		if left < shardSize {
			shardSize = left
		}

		read, err := io.CopyBuffer(h, io.LimitReader(r, shardSize), *bufp)
		if err != nil {
			// Read's failed for object with right size, at different offsets.
			return errFileCorrupt
		}

		left -= read
		if !bytes.Equal(h.Sum(nil), hashBuf[:n]) {
			return errFileCorrupt
		}
	}
	return nil
}

	if !st.Mode().IsRegular() {
		file.Close()
		return nil, errIsNotRegular
	}

	if st.Size() < offset+length {
		// Expected size cannot be satisfied for
		// requested offset and length
		file.Close()
		return nil, errFileCorrupt
	}

	if offset > 0 {
		if _, err = file.Seek(offset, io.SeekStart); err != nil {
			file.Close()
			return nil, err
		}
	}

11;\n}\n\n.order-12 {\n  -ms-flex-order: 12;\n  order: 12;\n}\n\n.offset-1 {\n  margin-left: 8.333333%;\n}\n\n.offset-2 {\n  margin-left: 16.666667%;\n}\n\n.offset-3 {\n  margin-left: 25%;\n}\n\n.offset-4 {\n  margin-left: 33.333333%;\n}\n\n.offset-5 {\n  margin-left: 41.666667%;\n}\n\n.offset-6 {\n  margin-left: 50%;\n}\n\n.offset-7 {\n  margin-left: 58.333333%;\n}\n\n.offset-8 {\n  margin-left: 66.666667%;\n}\n\n.offset-9 {\n  margin-left: 75%;\n}\n\n.offset-10 {\n  margin-left: 83.333333%;\n}\n\n.offset-11 {\n...