處理路徑或直接攔截管道時，將獲得ApplicationCall的上下文。 該呼叫包含一個名為response的屬性，允許發出響應。
上下文
使用路由功能時，您可以訪問路由處理程式中的call屬性：
routing {
get("/") {
call.respondText("Request uri: ${call.request.uri}")
}
}
複製程式碼當攔截請求時，攔截中的lambda處理程式也具有可用的call屬性：
intercept(ApplicationCallPipeline.Call) {
if (call.request.uri == "/") {
call.respondText("Test String")
}
}
複製程式碼控制HTTP headers和status
您可以控制響應的生成方式，HTTP status，headers，cookie等。
作為響應的一部分，您可以訪問其內部上下文：
val call: ApplicationCall = response.call
val pipeline: ApplicationSendPipeline = response.pipeline
複製程式碼headers:
val headers: ResponseHeaders = response.headers
複製程式碼用於設定Set-Cookie標頭的便捷cookie例項：
val cookies: ResponseCookies = response.cookies
複製程式碼獲取和更改HTTP status：
response.status(HttpStatusCode.OK) - Sets the HttpStatusCode to a predefined standard one
response.status(HttpStatusCode(418, "I'm a tea pot")) - Sets the HttpStatusCode to a custom status code
val status: HttpStatusCode? = response.status() - Gets the currently set HttpStatusCode if set
response.contentType(ContentType.Text.Plain.withCharset(Charsets.UTF_8)) - Typed way for setting the Content-Type (for ContentType.Application.Json the default charset is UTF_8 without making it explicit)
response.contentType("application/json; charset=UTF-8") - Untyped way for setting the Content-Type header
複製程式碼自定義headers:
response.header("X-My-Header", "my value") - Appends a custom header
response.header("X-My-Times", 1000) - Appends a custom header
response.header("X-My-Times", 1000L) - Appends a custom header
response.header("X-My-Date", Instant.EPOCH) - Appends a custom header
複製程式碼設定標頭的便捷方法：
response.etag("33a64df551425fcc55e4d42a148795d9f25f89d4") - Sets the ETag used for caching
response.lastModified(ZonedDateTime.now()) - Sets the Last-Modified header
response.contentLength(1024L) - Sets the Content-Length. This is generally automatically set when sending the payload
response.cacheControl(CacheControl.NoCache(CacheControl.Visibility.Private)) - Sets the Cache-Control header in a typed way
response.expires(LocalDateTime.now()) - Sets the Expires header
response.contentRange(1024L until 2048L, 4096L) - Sets the Content-Range header (check the PartialContent feature)
複製程式碼HTTP/2 Pushing和HTTP/1連結頭
call支援Pushing功能。
- 在HTTP/2中，使用Pushing功能
- 在HTTP/1.2中，它將連結頭新增為一個提示
routing {
get("/") {
call.push("/style.css")
}
}
複製程式碼注：Pushing減少了請求和頁面顯示之間的時間。但請注意，事先傳送內容可能會傳送已由客戶端快取的內容。
重定向
您可以使用respondRedirect方法輕鬆生成重定向響應，使用Location標頭髮送301 Moved Permanently或302 Found重定向。
call.respondRedirect("/moved/here", permanent = true)
複製程式碼傳送響應內容
傳送通用內容（與Content negotiation相容）：
call.respond(MyDataClass("hello", "world")) - Check the Content Negotiation section
call.respond(HttpStatusCode.NotFound, MyDataClass("hello", "world")) - Specifies a status code, and sends a payload in a single call. Check StatusPages
複製程式碼傳送文字資訊：
call.respondText("text") - Just a string with the body
call.respondText("p { background: red; }", contentType = ContentType.Text.CSS, status = HttpStatusCode.OK) { ... } - Sending a text specifying the ContentType, the HTTP Status and configuring the OutgoingContent
call.respondText { "string" } - Responding a string with a suspend provider
call.respondText(contentType = ..., status = ...) { "string" } - Responding a string with a suspend provider
call.respond(TextContent("{}", ContentType.Application.Json)) - Responding a string without adding a charset to the Content-Type
複製程式碼傳送byte陣列：
call.respondBytes(byteArrayOf(1, 2, 3)) - A ByteArray with a binary body
複製程式碼傳送檔案：
call.respondFile(File("/path/to/file")) - Sends a file
call.respondFile(File("basedir"), "filename") { ... } - Send a file and configures the OutgoingContent
複製程式碼傳送URL編碼的表單（application/x-www-form-urlencoded）：
Use Parameters.formUrlEncode. Check the Utilities page for more information about this.
複製程式碼使用Writer傳送分塊內容：
call.respondWrite { write("hello"); write("world") } - Sends text using a writer. This is used with the HTML DSL
call.respondWrite(contentType = ..., status = ...) { write("hello"); write("world") } - Sends text using a writer and specifies a contentType and a status
複製程式碼使檔案可下載
您可以通過新增Content-Disposition標頭使檔案“可下載”。以無型別的方式，您可以執行以下操作：
call.response.header(HttpHeaders.ContentDisposition, "attachment; filename=\"myfilename.bin\"")
複製程式碼但是Ktor還提供了一種帶有正確轉義的型別化方法來生成此標頭：
call.response.header(HttpHeaders.ContentDisposition, ContentDisposition.Attachment.withParameter(ContentDisposition.Parameters.FileName, "myfilename.bin").toString())
複製程式碼Content negotiation(介紹)
在配置用於Content negotiation的外掛時，管道可以接受call.respond方法的其他型別。
- 傳送 HTML DSL
- 傳送 HTMLFreeMarker
- 傳送data class生成的json