assertThat(request.header("Host")).isNull()
    assertThat(request.header("Accept-Encoding")).isNull()

    // No extra headers in the application's response.
    val response = client.newCall(request).execute()
    assertThat(request.header("Content-Encoding")).isNull()
    assertThat(response.body.string()).isEqualTo("abcabcabc")
  }

  @Test
  fun networkInterceptorsCanChangeRequestMethodFromGetToPost() {

				w.Header().Set(xhttp.AmzServerSideEncryptionKmsContext, kmsCtx)
			}
		case crypto.SSEC:
			w.Header().Set(xhttp.AmzServerSideEncryptionCustomerAlgorithm, r.Header.Get(xhttp.AmzServerSideEncryptionCustomerAlgorithm))
			w.Header().Set(xhttp.AmzServerSideEncryptionCustomerKeyMD5, r.Header.Get(xhttp.AmzServerSideEncryptionCustomerKeyMD5))
		}
		objInfo.ETag = getDecryptedETag(r.Header, objInfo, false)
	}

            Doc(
                """
                By default, if no HTTP Authorization header is provided, required for
                OpenID Connect authentication, it will automatically cancel the request
                and send the client an error.

                If `auto_error` is set to `False`, when the HTTP Authorization header
                is not available, instead of erroring out, the dependency result will

			headerMap[strings.ToLower(k)] = vv
		}
	}

	// Get header keys.
	headers := []string{"host"}
	for k := range headerMap {
		headers = append(headers, k)
	}
	sort.Strings(headers)

	// Get canonical headers.
	var buf bytes.Buffer
	for _, k := range headers {
		buf.WriteString(k)
		buf.WriteByte(':')
		switch {
		case k == "host":

 */
package okhttp3.internal.http1

import okhttp3.Headers
import okio.BufferedSource

/**
 * Parse all headers delimited by "\r\n" until an empty line. This throws if headers exceed 256 KiB.
 */
class HeadersReader(val source: BufferedSource) {
  private var headerLimit = HEADER_LIMIT.toLong()

  /** Read a single line counted against the header size limit. */
  fun readLine(): String {

```

而且你还可以根据你的需要响应不同的对象，比如常用的 `dict`，数据库model等。

如果你定义了 `response_model`，程序会自动根据`response_model`来过滤和转换你响应的对象。

**FastAPI** 会使用这个 *临时* 响应对象去装在这些cookies信息 (同样还有headers和状态码等信息), 最终会将这些信息和通过`response_model`转化过的数据合并到最终的响应里。

你也可以在depend中定义`Response`参数，并设置cookie和header。

## 直接响应 `Response`

你还可以在直接响应`Response`时直接创建cookies。

你可以参考[Return a Response Directly](response-directly.md){.internal-link target=_blank}来创建response

from fastapi import FastAPI, HTTPException

app = FastAPI()

items = {"foo": "The Foo Wrestlers"}


@app.get("/items-header/{item_id}")
async def read_item_header(item_id: str):
    if item_id not in items:
        raise HTTPException(
            status_code=404,
            detail="Item not found",
            headers={"X-Error": "There goes my error"},
        )

    assertThat(response.protocol).isEqualTo(protocol)
    val logs = testLogHandler.takeAll()
    assertThat(firstFrame(logs, "HEADERS")!!, "header logged")
      .contains("HEADERS       END_HEADERS")
    // While MockWebServer waits to read the client's HEADERS frame before sending the response, it
    // doesn't wait to read the client's DATA frame and may send a DATA frame before the client

* `path` - The file path to the file to stream.
* `headers` - Any custom headers to include, as a dictionary.
* `media_type` - A string giving the media type. If unset, the filename or path will be used to infer a media type.
* `filename` - If set, this will be included in the response `Content-Disposition`.

File responses will include appropriate `Content-Length`, `Last-Modified` and `ETag` headers.

```Python hl_lines="2  10"

**FastAPI** verwendet diese *vorübergehende* Response, um die Cookies (auch Header und Statuscode) zu extrahieren und fügt diese in die endgültige Response ein, die den von Ihnen zurückgegebenen Wert enthält, gefiltert nach einem beliebigen `response_model`.

Sie können den `Response`-Parameter auch in Abhängigkeiten deklarieren und darin Cookies (und Header) setzen.

## Eine `Response` direkt zurückgeben