如何在使用 Gradle 的 AppEngine 项目中使用 Kotlin

因为AppEngine执行编译.类文件，它不关心JVM语言生成了这些文件.这意味着我们可以使用Kotlin .

One way to do this is by using Gradle and the Gradle App Engine plugin. Create a project with a build.gradle that looks something like this. Then add the Kotlin dependencies and apply the plugin. The final build file looks something like this:

buildscript {
    ext.kotlin_version = '1.0.6' //replace with latest Kotlin version
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath 'com.google.appengine:gradle-appengine-plugin:1.9.32' //Replace with latest GAE plugin version
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
    }
}

repositories {
    mavenCentral();
}

apply plugin: 'java'
apply plugin: 'kotlin'
apply plugin: 'war'
apply plugin: 'appengine'

sourceCompatibility = JavaVersion.VERSION_1_7
targetCompatibility = JavaVersion.VERSION_1_7

dependencies {
    appengineSdk 'com.google.appengine:appengine-java-sdk:1.9.32' //Replace with latest GAE SDK version
    compile 'javax.servlet:servlet-api:2.5'
    compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
}

appengine {
    downloadSdk = true
    appcfg {
        oauth2 = true
    }
}

Since M11 you don't need to have a separate directory for Kotlin files so you can just add your .kt files to src/main/java.