运行示例并访问 <a href="http://127.0.0.1:8000/items/3" class="external-link" target="_blank">http://127.0.0.1:8000/items/3</a>，返回的响应如下：

```JSON
{"item_id":3}
```

!!! check "检查"

    注意，函数接收并返回的值是 `3`（ `int`），不是 `"3"`（`str`）。

    **FastAPI** 通过类型声明自动<abbr title="将来自 HTTP 请求中的字符串转换为 Python 数据类型">**解析**请求中的数据</abbr>。

## 数据校验

public final class okhttp3/android/AndroidAsyncDns : okhttp3/AsyncDns {
	public static final field Companion Lokhttp3/android/AndroidAsyncDns$Companion;
	public fun <init> (Lokhttp3/AsyncDns$DnsClass;Landroid/net/Network;)V
	public synthetic fun <init> (Lokhttp3/AsyncDns$DnsClass;Landroid/net/Network;ILkotlin/jvm/internal/DefaultConstructorMarker;)V
	public fun query (Ljava/lang/String;Lokhttp3/AsyncDns$Callback;)V
}

### ✅ ⚫️

📂 👆 🖥 <a href="http://127.0.0.1:8000" class="external-link" target="_blank">http://127.0.0.1:8000</a>.

👆 🔜 👀 🎻 📨:

```JSON
{"message": "Hello World"}
```

### 🎓 🛠️ 🩺

🔜 🚶 <a href="http://127.0.0.1:8000/docs" class="external-link" target="_blank">http://127.0.0.1:8000/docs</a>.

👆 🔜 👀 🏧 🎓 🛠️ 🧾 (🚚 <a href="https://github.com/swagger-api/swagger-ui" class="external-link" target="_blank">🦁 🎚</a>):

Thanks to <a href="https://www.starlette.io/testclient/" class="external-link" target="_blank">Starlette</a>, testing **FastAPI** applications is easy and enjoyable.

It is based on <a href="https://www.python-httpx.org" class="external-link" target="_blank">HTTPX</a>, which in turn is designed based on Requests, so it's very familiar and intuitive.

        return analyze(listOf(element), mode)
    }

    fun getOrigin(file: VirtualFile): KtSymbolOrigin

    enum class AnalysisMode {
        ALL_COMPILER_CHECKS,
        FULL,
        PARTIAL_WITH_DIAGNOSTICS,
        PARTIAL
    }
}

class Fe10AnalysisContext(
    facade: Fe10AnalysisFacade,
    val resolveSession: ResolveSession,
    val deprecationResolver: DeprecationResolver,

 */
class HpackRoundTripTest : HpackDecodeTestBase() {
  internal class StoriesTestProvider : SimpleProvider() {
    override fun arguments(): List<Any> = createStories(RAW_DATA)
  }

  private val bytesOut = Buffer()
  private val hpackWriter = Hpack.Writer(out = bytesOut)

  @ParameterizedTest
  @ArgumentsSource(StoriesTestProvider::class)
  fun testRoundTrip(story: Story) {
    assumeFalse(

      // Oracle JDK. Note that we don't support HTTP/2 or other nice features on Robolectric.
      val sslContextClass = Class.forName("sun.security.ssl.SSLContextImpl")
      val context = readFieldOrNull(sslSocketFactory, sslContextClass, "context") ?: return null
      readFieldOrNull(context, X509TrustManager::class.java, "trustManager")
    } catch (e: ClassNotFoundException) {
      null
    } catch (e: RuntimeException) {

* 업로드 된 파일의 메타데이터를 얻을 수 있습니다.
* <a href="https://docs.python.org/3/glossary.html#term-file-like-object" class="external-link" target="_blank">file-like</a>  `async` 인터페이스를 갖고 있습니다.
* file-like object를 필요로하는 다른 라이브러리에 직접적으로 전달할 수 있는 파이썬 <a href="https://docs.python.org/3/library/tempfile.html#tempfile.SpooledTemporaryFile" class="external-link" target="_blank">`SpooledTemporaryFile`</a> 객체를 반환합니다.

### `UploadFile`

  fun clear(hostname: String): FakeDns {
    hostAddresses.remove(hostname)
    return this
  }

  @Throws(UnknownHostException::class)
  fun lookup(
    hostname: String,
    index: Int,
  ): InetAddress {
    return hostAddresses[hostname]!![index]
  }

  @Throws(UnknownHostException::class)
  override fun lookup(hostname: String): List<InetAddress> {
    requestedHosts.add(hostname)

## Let's Encrypt

Antes de Let's Encrypt, esses certificados HTTPS eram vendidos por terceiros confiáveis.

O processo de aquisição de um desses certificados costumava ser complicado, exigia bastante papelada e os certificados eram bastante caros.