{* ../../docs_src/request_files/tutorial001_an_py39.py hl[14] *}

Using `UploadFile` has several advantages over `bytes`:

* You don't have to use `File()` in the default value of the parameter.
* It uses a "spooled" file:
    * A file stored in memory up to a maximum size limit, and after passing this limit it will be stored in disk.

{* ../../docs_src/request_files/tutorial001_an_py39.py hl[14] *}

Utilizar `UploadFile` tem várias vantagens sobre `bytes`:

* Você não precisa utilizar o `File()` no valor padrão do parâmetro.
* Ele utiliza um arquivo "spooled":
    * Um arquivo armazenado na memória até um limite máximo de tamanho, e após passar esse limite, ele será armazenado no disco.

{* ../../docs_src/request_files/tutorial001_an_py39.py hl[14] *}

Usar `UploadFile` tiene varias ventajas sobre `bytes`:

* No tienes que usar `File()` en el valor por defecto del parámetro.
* Usa un archivo "spooled":
    * Un archivo almacenado en memoria hasta un límite de tamaño máximo, y después de superar este límite, se almacenará en el disco.

这种方式把文件的所有内容都存储在内存里，适用于小型文件。

不过，很多情况下，`UploadFile` 更好用。

## 含 `UploadFile` 的文件参数

定义文件参数时使用 `UploadFile`：

{* ../../docs_src/request_files/tutorial001.py hl[12] *}

`UploadFile` 与 `bytes` 相比有更多优势：

* 使用 `spooled` 文件：
    * 存储在内存的文件超出最大上限时，FastAPI 会把文件存入磁盘；
* 这种方式更适于处理图像、视频、二进制文件等大型文件，好处是不会占用所有内存；
* 可获取上传文件的元数据；

    return planConnectToRoute(newRouteSelection.next(), newRouteSelection.routes)
  }

  /**
   * Returns a plan to reuse a pooled connection, or null if the pool doesn't have a connection for
   * this address.
   *
   * If [planToReplace] is non-null, this will swap it for a pooled connection if that pooled
   * connection uses HTTP/2. That results in fewer sockets overall and thus fewer TCP slow starts.
   */

    /**
     * Process a model object, potentially returning a pooled or optimized version.
     *
     * <p>This method is called during model building for various model objects.
     * Implementations can:</p>
     * <ul>
     *   <li>Return the same object if no processing is desired</li>
     *   <li>Return a pooled equivalent object to reduce memory usage</li>

 *     list of available routes.
 *
 * If the pool gains an eligible connection while DNS, TCP, or TLS work is in flight, this finder
 * will prefer pooled connections. Only pooled HTTP/2 connections are used for such de-duplication.
 *
 * It is possible to cancel the finding process by canceling its call.
 *

 * Fix: Support the `PATCH` method.
 * Fix: Support request bodies on `DELETE` method.
 * Fix: Drop the `okhttp-protocols` module.
 * Internal: Replaced internal byte array buffers with pooled buffers ("OkBuffer").


## Version 1.3.0

_2014-01-11_

 * New: Support for "PATCH" HTTP method in client and MockWebServer.
 * Fix: Drop `Content-Length` header when redirected from POST to GET.

System.out.println("REQUEST 1 (new connection)");
try (Response response = client.newCall(request).execute()) {
  // Consume and discard the response body.
  response.body().source().readByteString();
}

System.out.println("REQUEST 2 (pooled connection)");
try (Response response = client.newCall(request).execute()) {
  // Consume and discard the response body.
  response.body().source().readByteString();
}
```

    // If we raced another call connecting to this host, coalesce the connections. This makes for
    // 3 different lookups in the connection pool!
    val pooled3 = routePlanner.planReusePooledConnection(this, routes)
    if (pooled3 != null) return pooled3.connection

    connection.withLock {
      connectionPool.put(connection)
      call.acquireConnectionNoEvents(connection)
    }