* 它接收你的应用程序的每一个**请求**.
* 然后它可以对这个**请求**做一些事情或者执行任何需要的代码.
* 然后它将**请求**传递给应用程序的其他部分 (通过某种*路径操作*).
* 然后它获取应用程序生产的**响应** (通过某种*路径操作*).
* 它可以对该**响应**做些什么或者执行任何需要的代码.
* 然后它返回这个 **响应**.

/// note | "技术细节"

如果你使用了 `yield` 关键字依赖, 依赖中的退出代码将在执行中间件*后*执行.

如果有任何后台任务(稍后记录), 它们将在执行中间件*后*运行.

///

## 创建中间件

要创建中间件你可以在函数的顶部使用装饰器 `@app.middleware("http")`.

中间件参数接收如下参数:

* `request`.

        """
        return await super().close()

    @classmethod
    def __get_validators__(cls: Type["UploadFile"]) -> Iterable[Callable[..., Any]]:
        yield cls.validate

    @classmethod
    def validate(cls: Type["UploadFile"], v: Any) -> Any:
        if not isinstance(v, StarletteUploadFile):
            raise ValueError(f"Expected UploadFile, received: {type(v)}")

```

1. Das ist die Generatorfunktion. Es handelt sich um eine „Generatorfunktion“, da sie `yield`-Anweisungen enthält.
2. Durch die Verwendung eines `with`-Blocks stellen wir sicher, dass das dateiähnliche Objekt geschlossen wird, nachdem die Generatorfunktion fertig ist. Also, nachdem sie mit dem Senden der Response fertig ist.

 * accounts. SIDs are commonly represented using a textual format such as
 * <tt>S-1-5-21-1496946806-2192648263-3843101252-1029</tt> but they may
 * also be resolved to yield the name of the associated Windows account
 * such as <tt>Administrators</tt> or <tt>MYDOM\alice</tt>.
 * <p>
 * Consider the following output of <tt>examples/SidLookup.java</tt>:
 * 
 * <pre>

## [Calls](https://square.github.io/okhttp/4.x/okhttp/okhttp3/-call/)

      afe.initCause(t);
      throw afe;
    }
  }

  /**
   * Delays, via Thread.sleep, for the given millisecond delay, but if the sleep is shorter than
   * specified, may re-sleep or yield until time elapses.
   */
  @SuppressWarnings("ThreadPriorityCheck") // TODO: b/175898629 - Consider onSpinWait?
  static void delay(long millis) throws InterruptedException {
    long startTime = System.nanoTime();

      afe.initCause(t);
      throw afe;
    }
  }

  /**
   * Delays, via Thread.sleep, for the given millisecond delay, but if the sleep is shorter than
   * specified, may re-sleep or yield until time elapses.
   */
  @SuppressWarnings("ThreadPriorityCheck") // TODO: b/175898629 - Consider onSpinWait?
  static void delay(long millis) throws InterruptedException {
    long startTime = System.nanoTime();

            // this test is mainly checking that the contents of /dontdelete aren't deleted under
            // any circumstances
            assertEquals(3, MoreFiles.listFiles(symlinkTarget).size());

            Thread.yield();
          }
        } finally {
          executor.shutdownNow();
        }
      }
    }
  }

  public void testDeleteRecursively_nonDirectoryFile() throws IOException {

              @SuppressWarnings("ThreadPriorityCheck") // doing our best to test for races
              public void realRun() {
                while (!at.compareAndSet(2.0, 3.0)) {
                  Thread.yield();
                }
              }
            });

    assertTrue(at.compareAndSet(1.0, 2.0));
    awaitTermination(t);
    assertBitEquals(3.0, at.get());
  }

```

1. Essa é a função geradora. É definida como "função geradora" porque contém declarações `yield` nela.
2. Ao utilizar o bloco `with`, nós garantimos que o objeto semelhante a um arquivo é fechado após a função geradora ser finalizada. Isto é, após a resposta terminar de ser enivada.