val body = "hello".toRequestBody()
    val headers = headersOf("User-Agent", "RequestTest")
    val method = "PUT"
    val request =
      Request(
        url = url,
        headers = headers,
        method = method,
        body = body,
      )
    assertThat(request.url).isEqualTo(url)
    assertThat(request.headers).isEqualTo(headers)
    assertThat(request.method).isEqualTo(method)

   readTimeoutMillis, retryOnConnectionFailure, socketFactory, sslSocketFactory, writeTimeoutMillis
 * **PushPromise**: headers, method, path, response
 * **Request**: body, cacheControl, headers, method, url
 * **Response**: body, cacheControl, cacheResponse, code, handshake, headers, message,
   networkResponse, priorResponse, protocol, receivedResponseAtMillis, request, sentRequestAtMillis

from fastapi import FastAPI, Header
from pydantic import BaseModel

app = FastAPI()


class CommonHeaders(BaseModel):
    host: str
    save_data: bool
    if_modified_since: str | None = None
    traceparent: str | None = None
    x_tag: list[str] = []


@app.get("/items/")
async def read_items(headers: Annotated[CommonHeaders, Header()]):

from fastapi import FastAPI, Header
from pydantic import BaseModel

app = FastAPI()


class CommonHeaders(BaseModel):
    host: str
    save_data: bool
    if_modified_since: Union[str, None] = None
    traceparent: Union[str, None] = None
    x_tag: list[str] = []


@app.get("/items/")
async def read_items(headers: CommonHeaders = Header()):

from fastapi import Cookie, FastAPI, Header, Query
from fastapi.testclient import TestClient
from pydantic import BaseModel, Field

app = FastAPI()


class Model(BaseModel):
    param: str = Field(alias="param_alias")


@app.get("/query")
async def query_model(data: Model = Query()):
    return {"param": data.param}


@app.get("/header")
async def header_model(data: Model = Header()):
    return {"param": data.param}

        if (headers != null) {
            headers.forEach(header -> callback.accept(header.getFirst(), header.getSecond()));
        }
    }

	}
	extractedSignedHeaders := make(http.Header)
	for _, header := range signedHeaders {
		// `host` will not be found in the headers, can be found in r.Host.
		// but its always necessary that the list of signed headers containing host in it.
		val, ok := reqHeaders[http.CanonicalHeaderKey(header)]
		if !ok {
			// try to set headers from Query String
			val, ok = reqQueries[header]
		}
		if ok {

  }

  @Test
  fun headers() {
    var headers: Headers = headersOf("", "")
    headers = mapOf("" to "").toHeaders()
    val get: String? = headers[""]
    val date: Date? = headers.getDate("")
    val instant: Instant? = headers.getInstant("")
    val size: Int = headers.size
    val name: String = headers.name(0)
    val value: String = headers.value(0)
    val names: Set<String> = headers.names()

  }

  /** Accept headers from the network and store them until the client calls [takeHeaders]. */
  fun receiveHeaders(
    headers: Headers,
    inFinished: Boolean,
  ) {
    assertLockNotHeld()

    val open: Boolean
    withLock {
      if (!hasResponseHeaders ||
        headers[Header.RESPONSE_STATUS_UTF8] != null ||
        headers[Header.TARGET_METHOD_UTF8] != null
      ) {

# Header 参数

定义 `Header` 参数的方式与定义 `Query`、`Path`、`Cookie` 参数相同。

## 导入 `Header`

首先，导入 `Header`：

{* ../../docs_src/header_params/tutorial001_an_py310.py hl[3] *}

## 声明 `Header` 参数

然后，使用和 `Path`、`Query`、`Cookie` 一样的结构定义 header 参数。

第一个值是默认值，还可以传递所有验证参数或注释参数：

{* ../../docs_src/header_params/tutorial001_an_py310.py hl[9] *}

/// note | 技术细节

`Header` 是 `Path`、`Query`、`Cookie` 的**兄弟类**，都继承自共用的 `Param` 类。