开源软件名称（OpenSource Name）：

javalin/javalin

开源软件地址(OpenSource Url)：

https://github.com/javalin/javalin

开源编程语言(OpenSource Language)：

Kotlin 82.3%

开源软件介绍(OpenSource Introduction)：

Javalin - A simple web framework for Java and Kotlin

Javalin is a very lightweight web framework for Kotlin and Java which supports WebSockets, HTTP2 and async requests. Javalin’s main goals are simplicity, a great developer experience, and first class interoperability between Kotlin and Java.

Javalin is more of a library than a framework. Some key points:

You don't need to extend anything
There are no @Annotations
There is no reflection
There is no other magic; just code.

General information:

❤️ Sponsor Javalin
The project webpage is javalin.io (repo for webpage is at github.com/javalin/javalin.github.io).
Documentation: javalin.io/documentation
Chat on Discord: https://discord.gg/sgak4e5NKv
Chat on Gitter: https://gitter.im/javalin-io/general
Contributions are very welcome: CONTRIBUTING.md
License summary: https://tldrlegal.com/license/apache-license-2.0-(apache-2.0)
Interesting issues: /tipsy/javalin/issues?q=label:INFO

Quickstart

Add dependency

Maven

<dependency>
    <groupId>io.javalin</groupId>
    <artifactId>javalin</artifactId>
    <version>4.6.4</version>
</dependency>

Gradle

implementation "io.javalin:javalin:4.6.4"

Start programming (Java)

import io.javalin.Javalin;

public class HelloWorld {
    public static void main(String[] args) {
        Javalin app = Javalin.create().start(7000);
        app.get("/", ctx -> ctx.result("Hello World"));
    }
}

Start programming (Kotlin)

import io.javalin.Javalin

fun main() {
    val app = Javalin.create().start(7000)
    app.get("/") { ctx -> ctx.result("Hello World") }
}

Examples

This section contains a few examples, mostly just extracted from the docs. All examples are in Kotlin, but you can find them in Java in the documentation (it's just syntax changes).

Api structure and server config

val app = Javalin.create { config ->
    config.defaultContentType = "application/json"
    config.autogenerateEtags = true
    config.staticFiles.add("/public")
    config.asyncRequestTimeout = 10_000L
    config.dynamicGzip = true
    config.enforceSsl = true
}.routes {
    path("users") {
        get(UserController::getAll)
        post(UserController::create)
        path(":user-id") {
            get(UserController::getOne)
            patch(UserController::update)
            delete(UserController::delete)
        }
        ws("events", userController::webSocketEvents)
    }
}.start(port)

WebSockets

app.ws("/websocket/:path") { ws ->
    ws.onConnect { ctx -> println("Connected") }
    ws.onMessage { ctx ->
        val user = ctx.message<User>(); // convert from json string to object
        ctx.send(user); // convert to json string and send back
    }
    ws.onClose { ctx -> println("Closed") }
    ws.onError { ctx -> println("Errored") }
}

Filters and Mappers

app.before("/some-path/*") { ctx ->  ... } // runs before requests to /some-path/*
app.before { ctx -> ... } // runs before all requests
app.after { ctx -> ... } // runs after all requests
app.exception(Exception.class) { e, ctx -> ... } // runs if uncaught Exception
app.error(404) { ctx -> ... } // runs if status is 404 (after all other handlers)

app.wsBefore("/some-path/*") { ws ->  ... } // runs before ws events on /some-path/*
app.wsBefore { ws -> ... } // runs before all ws events
app.wsAfter { ws -> ... } // runs after all ws events
app.wsException(Exception.class) { e, ctx -> ... } // runs if uncaught Exception in ws handler

JSON-mapping

var todos = arrayOf(...)
app.get("/todos") { ctx -> // map array of Todos to json-string
    ctx.json(todos)
}
app.put("/todos") { ctx -> // map request-body (json) to array of Todos
    todos = ctx.body<Array<Todo>>()
    ctx.status(204)
}

File uploads

app.post("/upload") { ctx ->
    ctx.uploadedFiles("files").forEach { (contentType, content, name, extension) ->
        FileUtil.streamToFile(content, "upload/$name")
    }
}