聽完這場分享後，您將了解如何用 Kotlin 打造全平台應用，並且對 Ktor 的 Client 元件及 Server 運作有更進一步的認識。 詳細資訊：https://tw.kotlin.tips/webinars/r6tibc/full-stack-development-with-kotlin

1. Kotlin
—
(Shengyou Fan)
JetBrains
2020/07/24

2. —

3. API
—
{
"data": [
{
"id": "...UUID...",
"title": "...",
"description": "...",
"completed": true
}
]
}

4. Ktor
—
https://ktor.io/
• Web Framework
• Asynchronous
• Servers + Clients
• Developed by
JetBrains
• Open Source
(Apache 2.0)

5. Ktor API
—
Server
Database
Client
Kotlin/JVM

6. —
https://plugins.jetbrains.com/plugin/10823-ktor

7. Exposed
Kotlin SQL Framework
—
https://github.com/JetBrains/Exposed

8. —
// gradle.properties
exposed_version=0.21.1
h2_version=1.4.200
// build.gradle
dependencies {
//...
// Exposed SQL Library
implementation "org.jetbrains.exposed:exposed-core:$ver"
implementation "org.jetbrains.exposed:exposed-dao:$ver"
implementation "org.jetbrains.exposed:exposed-jdbc:$ver"
implementation "org.jetbrains.exposed:exposed-jodatime:$ver"
// H2 database
implementation "com.h2database:h2:$ver"
}

9. DAO
—
object Tasks : UUIDTable() {
val title = varchar("title", 255)
val description = text("description")
var completed = bool("completed")
val createdAt = datetime("created_at")
val updatedAt = datetime("updated_at")
}
class Task(id: EntityID<UUID>) : UUIDEntity(id) {
companion object : UUIDEntityClass<Task>(Tasks)
var title by Tasks.title
var description by Tasks.description
var completed by Tasks.completed
var createdAt by Tasks.createdAt
var updatedAt by Tasks.updatedAt
}

10. —
data class TaskResponse (
val id:UUID,
val title: String,
val description: String,
val completed: Boolean
)

11. Ktor Feature
—
Client
Ktor App
HTTP Server
Feature
Feature
Feature

12. —
// build.gradle
dependencies {
//...
// GSON
implementation "io.ktor:ktor-gson:$ver"
}

13. Feature
—
install(ContentNegotiation) {
gson {
}
}

14. —
Database.connect(
url = "...",
driver = "..."
)

15. —
transaction {
SchemaUtils.create(Tasks)
}
transaction {
for (i in 1..10) {
val task = Task.new {
title = "Task $i"
description = "..."
completed = false
createdAt = DateTime.now()
updatedAt = DateTime.now()
}
}
}

16. Routing
—
routing {
}

17. HTTP Method
—
routing {
get("/api/tasks") {
}
}

18. val tasks = transaction {
Task.all().map {
TaskResponse(
it.id.value,
it.title,
it.description,
it.completed,
it.createdAt.toString("..."),
it.updatedAt.toString("...")
)
}
}
—

19. Data Class
—
get("/api/tasks") {
// ...
call.respond(mapOf("data" to tasks))
}

20. —
post("/api/tasks") {
val request = call.receive<TaskRequest>()
val data = transaction {
val task = Task.new {
title = request.title
description = request.description
completed = false
createdAt = DateTime.now()
updatedAt = DateTime.now()
}
// ...
}
call.respond(mapOf("data" to data))
}

21. —
patch("/api/tasks/{id}/complete") {
val id = UUID.fromString(call.parameters["id"])
val data = transaction {
val task = Task.findById(id)
if (task != null) {
task.completed = true
} else {
throw ModelNotFoundException()
}
}
call.respond(mapOf("data" to data))
}

22. —
delete("/api/tasks/{id}/delete") {
val id = UUID.fromString(call.parameters["id"])
transaction {
val task = Task.findById(id)
if (task != null) {
task.delete()
} else {
throw ModelNotFoundException()
}
}
call.respond(HttpStatusCode.NoContent)
}

23. —
// build.gradle
plugins {
id 'com.google.cloud.tools.jib' version '2.2.0'
}
$ gradle jib --image=<MY IMAGE>
https://github.com/GoogleContainerTools/jib

24. —
• Ktor
• Application Call Request & Response
• Routing
• API (JSON)
• Exposed DB

25. (Shengyou)
shengyou.fan@jetbrains.com
Q&A
—
Kotlin