ktor-sample

Ktor

Ktor is an asynchronous framework for creating microservices, web applications and more. Written in Kotlin from the ground up.

  • Application.kt

import io.ktor.server.engine.*
import io.ktor.server.netty.*
import com.example.plugins.*

fun main() {
    embeddedServer(Netty, port = 8080, host = "127.0.0.1") {
        configureRouting()
    }.start(wait = true)
}
  • Routing.kt

import io.ktor.routing.*
import io.ktor.application.*
import io.ktor.response.*


fun Application.configureRouting() {

    routing {
        get("/") {
                call.respondText("Hello Ktor!")
            }
    }
}
  • Runs embedded web server on localhost:8080
  • Installs routing and responds with Hello, world! when receiving a GET http request for the root path

==================================================

  • Ktor Request API With PostMan
  • Routing.kt

import io.ktor.routing.*
import io.ktor.application.*
import io.ktor.request.*
import io.ktor.response.*


fun Application.configureRouting() {

    routing {
        get("/") {
            println("URI: ${call.request.uri}")
            println("Headers: ${call.request.headers.names()}")

            // Request
            println("User-Agent: ${call.request.headers["User-Agent"]}")
            println("Accept: ${call.request.headers["Accept"]}")
            println("Query Params: ${call.request.queryParameters.names()}")
            println("Name: ${call.request.queryParameters["name"]}")
            println("Email: ${call.request.queryParameters["email"]}")


            call.respondText("Hello Ktor!")
        }
    }
}


Put This Url In Postman And Send Request
http://127.0.0.1:8080?name=Your Name&[email protected]


This Is Result After Send Url In Run Application IntelliJ IDEA Ultimate

URI: /?name=YourName&[email protected]
Headers: [User-Agent, Accept, Postman-Token, Host, Accept-Encoding, Connection]
User-Agent: PostmanRuntime/7.28.4
Accept: */*
Query Params: [name, email]
Name: YourName
Email: [email protected]

==================================================

  • Ktor Url Parameters With PostMan

  • Routing.kt

import io.ktor.routing.*
import io.ktor.application.*
import io.ktor.request.*
import io.ktor.response.*


fun Application.configureRouting() {

    routing {
        
        // Url Parameters
        get("iphones/{page}") {
            val pageNumber = call.parameters["page"]
            call.respondText("Your are no Page number : $pageNumber")
        }
    }
}


Put This Url In Postman And Send Request
http://127.0.0.1:8080/iphones/2

==================================================

  • Ktor Request Body With PostMan

  • build.gradle.kts

plugins {
    application
    kotlin("jvm") version "1.5.31" // or kotlin("multiplatform") or any other kotlin plugin
    kotlin("plugin.serialization") version "1.5.31"
}

dependencies {
    implementation("io.ktor:ktor-serialization:$ktor_version")
}
  • Routing.kt

import io.ktor.routing.*
import io.ktor.application.*
import io.ktor.request.*
import io.ktor.response.*
import kotlinx.serialization.*

fun Application.configureRouting() {

    routing {
        
        // Request Body
        post("/login") {
            val userInfo = call.receive<UserInfo>()
            println(userInfo)
            call.respondText("Everything Working Fine!")
        }
    }
}


@Serializable
data class UserInfo(
    val name:String,
    val email:String
)
  • Application.kt

install(ContentNegotiation){
    json()
}


1- Put This Url In Postman And Send Request
http://127.0.0.1:8080/login

2- select POST

3- In Body choose format JSON and write json code
{
    "name": "YourName",
    "email": "[email protected]"
}
4- Send


This Is Result After Send Url In Run Application IntelliJ IDEA Ultimate

UserInfo(name=YourName, [email protected])

==================================================

  • Ktor Response – Sending JSON Response With PostMan

  • Routing.kt

//GatewayTimeout
call.respondText("Wrong!!!!!!!!!", status = HttpStatusCode.GatewayTimeout)

// OR NotFound
call.respondText("Not Found !!!!!!!!!", status = HttpStatusCode.NotFound)
  • if you want Sending JSON Response To PostMan

@Serializable
data class UserInfo(
    val name:String,
    val email:String
)


    val responseObj = UserInfo("YourName","[email protected]")
    call.respond(responseObj)


In PostMan
Select GET and Put This Url http://127.0.0.1:8080/
and SEND
The Result in PostMan
=======
{
    "name": "YourName",
    "email": "[email protected]"
}

==================================================

  • Ktor Response – Downloading a File

— Step one

1- First create a New Directory name = files
2- add some photo in file

— Step Two

  • Routing.kt

        // Ktor Response - Downloading a File
        get("/fileDownload") {
            val file = File("files/pic.png")

            call.response.header(
                HttpHeaders.ContentDisposition,
                ContentDisposition.Attachment.withParameter(
                    ContentDisposition.Parameters.FileName, "pic.png"
                ).toString()
            )
            call.respondFile(file)

        }


        // Ktor Response - Open a File In Browser
        get("/fileOpen") {
            val file = File("files/pic.png")

            call.response.header(
                HttpHeaders.ContentDisposition,
                ContentDisposition.Inline.withParameter(
                    ContentDisposition.Parameters.FileName, "pic.png"
                ).toString()
            )
            call.respondFile(file)

        }

GitHub

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