Now, let's see how you could use that to return a custom response.

Let's say that you want to return an <a href="https://en.wikipedia.org/wiki/XML" class="external-link" target="_blank">XML</a> response.

You could put your XML content in a string, put that in a `Response`, and return it:

{* ../../docs_src/response_directly/tutorial002_py39.py hl[1,18] *}

    return new Stats(count, mean, sumOfSquaresOfDeltas, min, max);
  }

  /** Returns the number of values. */
  public long count() {
    return count;
  }

  /**
   * Returns the <a href="http://en.wikipedia.org/wiki/Arithmetic_mean">arithmetic mean</a> of the
   * values. The count must be non-zero.
   *
   * <p>If these values are a sample drawn from a population, this is also an unbiased estimator of

  fun run() {
    val formBody =
      FormBody
        .Builder()
        .add("search", "Jurassic Park")
        .build()
    val request =
      Request(
        url = "https://en.wikipedia.org/w/index.php".toHttpUrl(),
        body = formBody,
      )

    client.newCall(request).execute().use { response ->
      if (!response.isSuccessful) throw IOException("Unexpected code $response")

///

## 사용자 정의 `Response` 반환하기
위 예제는 필요한 모든 부분을 보여주지만, 아직 유용하지는 않습니다. 사실 데이터를 직접 반환하면 **FastAPI**가 이를 `JSONResponse`에 넣고 `dict`로 변환하는 등 모든 작업을 자동으로 처리합니다.

이제, 사용자 정의 응답을 반환하는 방법을 알아보겠습니다.

예를 들어 <a href="https://en.wikipedia.org/wiki/XML" class="external-link" target="_blank">XML</a> 응답을 반환하고 싶다고 가정해보겠습니다.

XML 내용을 문자열에 넣고, 이를 `Response`에 넣어 반환할 수 있습니다:

{* ../../docs_src/response_directly/tutorial002.py hl[1,18] *}

## 참고 사항

///

## 返回自定义 `Response`

上面的例子展示了需要的所有部分，但还不够实用，因为你本可以只是直接返回 `item`，而**FastAPI** 默认帮你把这个 `item` 放到 `JSONResponse` 中，又默认将其转换成了 `dict`等等。

现在，让我们看看你如何才能返回一个自定义的响应。

假设你想要返回一个 <a href="https://en.wikipedia.org/wiki/XML" class="external-link" target="_blank">XML</a> 响应。

你可以把你的 XML 内容放到一个字符串中，放到一个 `Response` 中，然后返回。

{* ../../docs_src/response_directly/tutorial002.py hl[1,18] *}

## 说明

    * Однако у этого есть **решение**.
* Есть **расширение** протокола **TLS** (того самого, что занимается шифрованием на уровне TCP, до HTTP) под названием **<a href="https://en.wikipedia.org/wiki/Server_Name_Indication" class="external-link" target="_blank"><abbr title="Server Name Indication – Указание имени сервера">SNI</abbr></a>**.

/**
 * A {@link ListenableFuture} which forwards all its method calls to another future. Subclasses
 * should override one or more methods to modify the behavior of the backing future as desired per
 * the <a href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p>Most subclasses can just use {@link SimpleForwardingListenableFuture}.
 *
 * @author Shardul Deo
 * @since 4.0
 */
@GwtCompatible

## 結論

透過這個教學，你應該對**環境變數**是什麼以及如何在 Python 中使用它們有了基本的了解。

你也可以在<a href="https://zh.wikipedia.org/wiki/%E7%8E%AF%E5%A2%83%E5%8F%98%E9%87%8F" class="external-link" target="_blank">環境變數 - 維基百科</a> (<a href="https://en.wikipedia.org/wiki/Environment_variable" class="external-link" target="_blank">Wikipedia for Environment Variable</a>) 中了解更多關於它們的資訊。

在許多情況下，環境變數的用途和適用性可能不會立刻顯現。但是在開發過程中，它們會在許多不同的場景中出現，因此瞭解它們是非常必要的。

For example, it doesn't receive `datetime` objects, as those are not compatible with JSON.

So, a `datetime` object would have to be converted to a `str` containing the data in <a href="https://en.wikipedia.org/wiki/ISO_8601" class="external-link" target="_blank">ISO format</a>.

The same way, this database wouldn't receive a Pydantic model (an object with attributes), only a `dict`.

You can use `jsonable_encoder` for that.

 * service. Subclasses should override one or more methods to modify the behavior of the backing
 * executor service as desired per the <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p><b>{@code default} method warning:</b> This class does <i>not</i> forward calls to {@code