你可以在 **FastAPI** 应用中使用 `CORSMiddleware` 来配置它。

* 导入 `CORSMiddleware`。
* 创建一个允许的源列表（由字符串组成）。
* 将其作为「中间件」添加到你的 **FastAPI** 应用中。

你也可以指定后端是否允许：

* 凭证（授权 headers，Cookies 等）。
* 特定的 HTTP 方法（`POST`，`PUT`）或者使用通配符 `"*"` 允许所有方法。
* 特定的 HTTP headers 或者使用通配符 `"*"` 允许所有 headers。

{* ../../docs_src/cors/tutorial001.py hl[2,6:11,13:19] *}

默认情况下，这个 `CORSMiddleware` 实现所使用的默认参数较为保守，所以你需要显式地启用特定的源、方法或者 headers，以便浏览器能够在跨域上下文中使用它们。

    // Test default state of not started.
    assertEquals(1, listenerLatch.getCount());
    assertFalse(task.isDone());
    assertFalse(task.isCancelled());

    // Start the task to put it in the RUNNING state.  Have to use a separate
    // thread because the task will block on the task latch after unblocking
    // the run latch.
    exec.execute(task);
    runLatch.await();

Com o **FastAPI**, utilizando o OpenAPI, você pode definir os nomes destes webhooks, os tipos das operações HTTP que a sua aplicação pode enviar (e.g. `POST`, `PUT`, etc.) e os **corpos** da requisição que a sua aplicação enviaria.

        public void onStartHtmlElement(String name) {
            attributes.clear();
        }

        @Override
        public void onHtmlElementAttribute(String name, String value) {
            attributes.put(name, value);
        }

        @Override
        public void onStartHtmlElementComplete(String name) {
            if (name.equals("li")) {
                unwindTo(Arrays.asList("ul", "ol"), visitor);

    @Override
    protected Map<AnEnum, String> create(Entry<AnEnum, String>[] entries) {
      Map<AnEnum, String> map = new HashMap<>();
      for (Entry<AnEnum, String> entry : entries) {
        map.put(entry.getKey(), entry.getValue());
      }
      return Maps.immutableEnumMap(map);
    }
  }

  @J2ktIncompatible
  @GwtIncompatible // suite
  @AndroidIncompatible // test-suite builders

        return false;
      } else if (candidate.equals(target)) {
        return true;
      }
    }
  }

  @Override
  public int size() {
    return elements.length;
  }

  // We're careful to put only E instances into the array in the mainline.
  // (In the backport, we don't need this suppression, but we keep it to minimize diffs.)
  @SuppressWarnings("unchecked")
  @Override
  public UnmodifiableIterator<E> iterator() {

   * simultaneously adopted and removed.
   */
  private val connections = ConcurrentLinkedQueue<RealConnection>()

  init {
    // Put a floor on the keep alive duration, otherwise cleanup will spin loop.
    require(keepAliveDuration > 0L) { "keepAliveDuration <= 0: $keepAliveDuration" }
  }

  fun idleConnectionCount(): Int =
    connections.count {

                                    .setMessage(e.getMessage())
                                    .setException(e));
                        }
                        cache.put(value, c);
                    }
                    return c;
                }
                return value;
            }
        };
    }

    private static final class InterpolateObjectAction {

 * CompactLinkedHashMap is an implementation of a Map with insertion or LRU iteration order,
 * maintained with a doubly linked list through the entries. All optional operations (put and
 * remove) are supported. Null keys and values are supported.
 *
 * <p>{@code containsKey(k)}, {@code put(k, v)} and {@code remove(k)} are all (expected and
 * amortized) constant time operations. Expected in the hashtable sense (depends on the hash

   * performance of a Bloom filter (yet only needs two 32bit hash functions).
   */
  MURMUR128_MITZ_32() {
    @Override
    public <T extends @Nullable Object> boolean put(
        @ParametricNullness T object,
        Funnel<? super T> funnel,
        int numHashFunctions,
        LockFreeBitArray bits) {
      long bitSize = bits.bitSize();