更新 `get_current_user`，讓它仍接收相同的權杖，但這次改用 JWT 權杖。

解碼收到的權杖、驗證它，並回傳目前的使用者。

如果權杖無效，立即回傳一個 HTTP 錯誤。

{* ../../docs_src/security/tutorial004_an_py310.py hl[93:110] *}

## 更新 `/token` 路徑操作 { #update-the-token-path-operation }

用權杖有效期建立一個 `timedelta`。

建立真正的 JWT access token 並回傳它。

{* ../../docs_src/security/tutorial004_an_py310.py hl[121:136] *}

### 關於 JWT「主體」`sub` 的技術細節 { #technical-details-about-the-jwt-subject-sub }

解码接收到的令牌，进行校验，并返回当前用户。

如果令牌无效，立即返回一个 HTTP 错误。

{* ../../docs_src/security/tutorial004_an_py310.py hl[93:110] *}

## 更新 `/token` 路径操作 { #update-the-token-path-operation }

用令牌的过期时间创建一个 `timedelta`。

创建一个真正的 JWT 访问令牌并返回它。

{* ../../docs_src/security/tutorial004_an_py310.py hl[121:136] *}

### 关于 JWT “主题” `sub` 的技术细节 { #technical-details-about-the-jwt-subject-sub }

  }

  /**
   * Guaranteed to throw an exception and leave the set unmodified.
   *
   * @since 12.0
   * @throws UnsupportedOperationException always
   * @deprecated Unsupported operation.
   */
  @CanIgnoreReturnValue
  @Deprecated
  @GwtIncompatible // NavigableSet
  @Override
  @DoNotCall("Always throws UnsupportedOperationException")
  public final @Nullable E pollFirst() {

     * read operations anyway:
     *
     * - All (unsynchronized) read operations must first read the "count" field, and should not
     * look at table entries if it is 0.
     *
     * - All (synchronized) write operations should write to the "count" field after structurally
     * changing any bin. The operations must not take any action that could even momentarily

```

... c’est parce que le générateur de client utilise l’**operation ID** interne OpenAPI pour chaque *chemin d'accès*.

OpenAPI exige que chaque operation ID soit unique parmi tous les *chemins d'accès*, donc FastAPI utilise le **nom de la fonction**, le **chemin**, et la **méthode/opération HTTP** pour générer cet operation ID, car de cette façon il peut s’assurer que les operation IDs sont uniques.

 * retrieval operations obtain elements at the head of the queue.
 *
 * <p>This is a classic &quot;bounded buffer&quot;, in which a fixed-sized array holds elements
 * inserted by producers and extracted by consumers. Once created, the capacity cannot be increased.
 * Attempts to {@code put} an element into a full queue will result in the operation blocking;

            if (existing != null) {
                return existing;
            }
        }

        // Check pool size limits using atomic operation
        if (!nonPooled) {
            int currentSize = this.connections.size();
            if (currentSize >= maxPoolSize) {
                // Try to remove idle connections
                removeIdleConnections();

Similar a como puedes [agregar `dependencies` a los *path operation decorators*](dependencies-in-path-operation-decorators.md), puedes agregarlos a la aplicación de `FastAPI`.

En ese caso, se aplicarán a todas las *path operations* en la aplicación:

{* ../../docs_src/dependencies/tutorial012_an_py310.py hl[17] *}

Ayrıca, bu router içindeki tüm *path operation*’lara uygulanacak bir `tags` listesi ve ek `responses` da ekleyebiliriz.

Ve router’daki tüm *path operation*’lara eklenecek, her request için çalıştırılıp çözülecek bir `dependencies` listesi de ekleyebiliriz.

/// tip | İpucu

participant dep_func as Dep scope="function"
participant operation as Path Operation

    client ->> dep_req: Start request
    Note over dep_req: Run code up to yield
    dep_req ->> dep_func: Pass dependency
    Note over dep_func: Run code up to yield
    dep_func ->> operation: Run path operation with dependency
    operation ->> dep_func: Return from path operation
    Note over dep_func: Run code after yield