*  *➡* 💪 🔌 <a href="https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.0.2.md#key-expression" class="external-link" target="_blank">🗄 3️⃣ 🧬</a> (👀 🌖 🔛) 🌐❔ ⚫️ 💪 ⚙️ 🔢 ⏮️ 🔢 &amp; 🍕 ⏮️ 📨 📨 *👆 🛠️*.

### ⏲ ➡ 🧬

/// warning

Extra keys passed to `Field` will also be present in the resulting OpenAPI schema for your application.
As these keys may not necessarily be part of the OpenAPI specification, some OpenAPI tools, for example [the OpenAPI validator](https://validator.swagger.io/), may not work with your generated schema.

///

## Recap

   | Unless otherwise specified (by system property or command-line switch), the first proxy
   | specification in this list marked as active will be used.
   |-->
  <proxies>
    <!-- proxy
     | Specification for one proxy, to be used in connecting to the network.
     |
    <proxy>
      <id>optional</id>
      <active>true</active>
      <protocol>http</protocol>

In this section we'll see how to use other middlewares.

## Adding ASGI middlewares

As **FastAPI** is based on Starlette and implements the <abbr title="Asynchronous Server Gateway Interface">ASGI</abbr> specification, you can use any ASGI middleware.

A middleware doesn't have to be made for FastAPI or Starlette to work, as long as it follows the ASGI spec.

          SSLContext.getInstance("TLS")
        }
    }
  }

  companion object {
    val isAvailable: Boolean

    val majorVersion = System.getProperty("java.specification.version")?.toIntOrNull()

    init {
      isAvailable =
        if (majorVersion != null) {
          majorVersion >= 9
        } else {
          try {
            // also present on JDK8 after build 252.

package replication

import (
	"encoding/xml"
	"fmt"
	"strings"

	"github.com/minio/pkg/v3/wildcard"
)

// DestinationARNPrefix - destination ARN prefix as per AWS S3 specification.
const DestinationARNPrefix = "arn:aws:s3:::"

// DestinationARNMinIOPrefix - destination ARN prefix for MinIO.
const DestinationARNMinIOPrefix = "arn:minio:replication:"

        "sun.net.www.protocol"
    };

    private static URLStreamHandlerFactory factory;

    /**
     * Sets the URL stream handler factory for the environment.  This
     * allows specification of the factory used in creating underlying
     * stream handlers.  This can be called once per JVM instance.
     *
     * @param factory The URL stream handler factory.
     */

        <configuration>
          <!-- Passing `-subpackages com.google.common` breaks things, so we explicitly exclude everything else instead. -->
          <!-- excludePackageNames requires specification of packages separately from "all subpackages".
               https://issues.apache.org/jira/browse/MJAVADOC-584 -->
          <excludePackageNames>

创建表单（`Form`）参数的方式与 `Body` 和 `Query` 一样：

```Python hl_lines="7"
{!../../docs_src/request_forms/tutorial001.py!}
```

例如，OAuth2 规范的 "密码流" 模式规定要通过表单字段发送 `username` 和 `password`。

<abbr title="specification">该规范</abbr>要求字段必须命名为 `username` 和 `password`，并通过表单字段发送，不能用 JSON。

使用 `Form` 可以声明与 `Body` （及 `Query`、`Path`、`Cookie`）相同的元数据和验证。

/// info | "说明"

`Form` 是直接继承自 `Body` 的类。

///

/// tip | "提示"

所以 OpenAPI为了相似的目的定义了自己的 <a href="https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.0.3.md#fixed-fields-20" class="external-link" target="_blank">`example`</a> (使用 `example`, 而不是 `examples`), 这也是文档 UI 所使用的 (使用 Swagger UI).

所以，虽然 `example` 不是JSON Schema的一部分，但它是OpenAPI的一部分，这将被文档UI使用。