**FastAPI** 會保留 `responses` 提供的額外資訊，並把它和你模型的 JSON Schema 結合。

例如，你可以宣告一個狀態碼為 `404` 的回應，使用一個 Pydantic 模型，並帶有自訂的 `description`。

以及一個狀態碼為 `200` 的回應，使用你的 `response_model`，但包含自訂的 `example`：

{* ../../docs_src/additional_responses/tutorial003_py310.py hl[20:31] *}

以上都會被結合並包含在你的 OpenAPI 中，並顯示在 API 文件：

<img src="/img/tutorial/additional-responses/image01.png">

			// For metadata values like "ö", "ÄMÄZÕÑ S3", and "öha, das sollte eigentlich
			// funktionieren", tested against a real AWS S3 bucket, S3 may encode incorrectly. For
			// example, "ö" was encoded as =?UTF-8?B?w4PCtg==?=, producing invalid UTF-8 instead
			// of =?UTF-8?B?w7Y=?=. This mirrors errors like the ä½ in another string.
			//

 * project to be able to run in a given runtime, all of its dependencies must also
 * support running in that runtime.
 *
 * Some projects have a strict set of runtimes they must support. For example, a
 * plugin that only runs in the daemon would declare the daemon as a target runtime,
 * while a worker action that executes in a worker must declare that it executes in
 * a worker.
 *

0.083 callEnd
```

Notice how no connect events are fired for the second call. It reused the connection from the first request for dramatically better performance.

### EventListener.Factory

/**
 * Tester to ensure forwarding wrapper works by delegating calls to the corresponding method with
 * the same parameters forwarded and return value forwarded back or exception propagated as is.
 *
 * <p>For example:
 *
 * {@snippet :
 * new ForwardingWrapperTester().testForwarding(Foo.class, new Function<Foo, Foo>() {
 *   public Foo apply(Foo foo) {
 *     return new ForwardingFoo(foo);
 *   }
 * });
 * }
 *

 * <a href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p><b>Warning:</b> The methods of {@code ForwardingCollection} forward <b>indiscriminately</b> to
 * the methods of the delegate. For example, overriding {@link #add} alone <b>will not</b> change
 * the behavior of {@link #addAll}, which can lead to unexpected behavior. In this case, you should

   * case the call may even time out before the target method is ever invoked.
   *
   * @param executor the ExecutorService that will execute the method calls on the target objects;
   *     for example, a {@link Executors#newCachedThreadPool()}.
   * @since 22.0
   */
  public static SimpleTimeLimiter create(ExecutorService executor) {
    return new SimpleTimeLimiter(executor);
  }

  @Override

   * context class loader will find resources from the class path. In environments where different
   * threads can have different class loaders, for example app servers, the context class loader
   * will typically have been set to an appropriate loader for the current thread.
   *
   * <p>In the unusual case where the context class loader is null, the class loader that loaded

 * <a href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p><b>Warning:</b> The methods of {@code ForwardingCollection} forward <b>indiscriminately</b> to
 * the methods of the delegate. For example, overriding {@link #add} alone <b>will not</b> change
 * the behavior of {@link #addAll}, which can lead to unexpected behavior. In this case, you should

 * access, the {@code ForwardingList} subclass should implement the {@code RandomAccess} interface.
 *
 * <p><b>Warning:</b> The methods of {@code ForwardingList} forward <b>indiscriminately</b> to the
 * methods of the delegate. For example, overriding {@link #add} alone <b>will not</b> change the
 * behavior of {@link #addAll}, which can lead to unexpected behavior. In this case, you should