Kotlin 在 Web 方面的应用
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- Kotlin is a general-purpose programming language that is static typed, supports OOP and FP, and was developed by JetBrains. Ktor is a web framework for Kotlin that supports asynchronous servers and clients. - Ktor allows building web applications using routing to define endpoints, application calls to handle requests and responses, and features like HTML rendering, JSON serialization, and database access using Exposed. - A full-stack Kotlin web application example was demonstrated using Ktor, Exposed ORM, and a MySQL database to build both a web UI and RESTful API for a todo list application.
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Kotlin 在 Web 方面的应用
- 1. Kotlin Web — (Shengyou Fan) GDG Shanghai Kotlin Everywhere 2019/11/02
- 2. — • Developer Advocate • Backend Developer • Open Source Community Organizer
- 3. Kotlin https://youtu.be/hg8oYJ8Ez8s • General-purpose • Static typing • OOP + FP • Developed by JetBrains • Open Source (Apache 2.0) https://kotlinlang.org/ Kotlin —
- 6. Ktor — https://ktor.io/ • Web Framework • Asynchronous • Servers + Clients • Developed by JetBrains • Open Source (Apache 2.0)
- 7. — OpenJDK 8+ IntelliJ IDEA Ktor Plugin
- 8. OpenJDK — $ curl -s "https://get.sdkman.io" | bash $ source "$HOME/.sdkman/bin/sdkman-init.sh" $ sdk install java $ sdk list java $ sdk current java $ sdk use java <version> $ sdk default java <version> $ sdk upgrade java https://sdkman.io/
- 13. HTTP Method — routing { get("/") { } }
- 16. — routing { get("/") { call.respondText("Hello, world") } }
- 17. ContentType HttpStatusCode — routing { get("/") { call.respondText( "Hello, world”, ContentType.Text.Plain, HttpStatusCode.OK ) } }
- 18. Auto build & reload — // resources/application.conf ktor { deployment { port = 8080 port = ${?PORT} } application { modules = [ ... ] } }
- 19. Auto build & reload — // resources/application.conf ktor { deployment { port = 8080 port = ${?PORT} watch = [ ... ] } application { modules = [ ... ] } }
- 21. Gradle — // build.gradle dependencies { //... implementation "io.ktor:ktor-html-builder:$ver" }
- 22. HTML DSL — get("/") { call.respondHtml { head { title { +"ToDo List" } } body { h1 { +"ToDo List" } p { +"a simple ToDo application" } } } }
- 23. HTML — <!DOCTYPE html> <html lang="zh-Hans"> <head> <meta charset="UTF-8"> <title>ToDo List</title> </head> <body> <h1>ToDo List</h1> <p>a simple ToDo application</p> </body> </html>
- 24. HTML DSL — get("/") { val tasks = mutableListOf<String>() for (i in 0..9) { tasks.add("Task $i") } call.respondHtml { head { title { +"ToDo List" } } body { h1 { +"ToDo List" } p { +"a simple ToDo application" } ul { tasks.map { li { +it } } } } } }
- 26. Gradle — // build.gradle dependencies { //... implementation "io.ktor:ktor-jackson:$ver" }
- 28. Ktor Feature — Client Ktor App HTTP Server Feature Feature Feature
- 29. JSON respond — data class TaskRespond ( val title: String, val completed: Boolean = false ) get("/api/v1/tasks") { val task = TaskRespond("Task 1”) call.respond( mapOf("task" to task) ) }
- 30. JSON respond — get("/api/v1/tasks") { val tasks = mutableListOf<TaskRespond>() for (i in 1..10) { tasks.add(TaskRespond("Task $i")) } call.respond( mapOf("tasks" to tasks) ) }
- 31. — version: "2" services: database: image: mysql:5.7 ports: - "...:3306" environment: MYSQL_ROOT_PASSWORD: ... MYSQL_DATABASE: ...
- 32. Exposed DB MySQL Connector — // build.gradle dependencies { //... implementation "org.jetbrains.exposed:exposed:$ver" implementation "mysql:mysql-connector-java:$ver" }
- 33. Table — object Tasks: IntIdTable() { val title = varchar("title", 255) val completed = bool("completed") val createdAt = datetime("created_at") val updatedAt = datetime("updated_at") }
- 34. Entity — class Task(id: EntityID<Int>) : IntEntity(id) { companion object : IntEntityClass<Task>(Tasks) var title by Tasks.title var completed by Tasks.completed var createdAt by Tasks.createdAt var updatedAt by Tasks.updatedAt }
- 35. — Database.connect( url = "...", driver = "com.mysql.jdbc.Driver", user = "...", password = "..." )
- 36. — transaction { SchemaUtils.drop(Tasks) SchemaUtils.create(Tasks) } transaction { for (i in 1..10) { Task.new { title = "Task $i" completed = listOf(true, false, false) .shuffled() .first() createdAt = DateTime.now() updatedAt = DateTime.now() } } }
- 37. Page & API — Database.connect( url = "...", driver = "com.mysql.jdbc.Driver", user = "...", password = "..." ) val tasks = transaction { Task.all().sortedByDescending { it.id }.map { TaskRespond(it.title, it.completed) } }
- 38. Page — get("/") { call.respondHtml { head { title { +"ToDo List" } } body { h1 { +"ToDo List" } p { +"a simple ToDo application" } ul { tasks.map { li { +it.title } } } } } }
- 39. API — get("/api/v1/tasks") { call.respond( mapOf("tasks" to tasks) ) }
- 41. — • Kotlin • Ktor • • Application Call Request & Response • Routing • Exposed DB • • API
- 42. — Talking Kotlin http://talkingkotlin.com/ktor-with-ryan-harter/Ktor https://ktor.io/servers/index.html KotlinConf https://youtu.be/V4PS3IjIzlw