这是我直接从Spark documentation拍摄的CorsRoute:
class CorsRoute(origin: String, methods: String, headers: String) {
init {
options("/*") { request, response ->
val accessControlRequestHeaders = request.headers("Access-Control-Request-Headers")
if (accessControlRequestHeaders != null) {
response.header("Access-Control-Allow-Headers", accessControlRequestHeaders)
}
val accessControlRequestMethod = request.headers("Access-Control-Request-Method")
if (accessControlRequestMethod != null) {
response.header("Access-Control-Allow-Methods", accessControlRequestMethod)
}
"OK"
}
before { request, response ->
response.header("Access-Control-Allow-Origin", origin)
response.header("Access-Control-Request-Method", methods)
response.header("Access-Control-Allow-Headers", headers)
response.type("application/json")
}
}
}
以下是我对CorsRoute的实例:
abstract class Route {
init {
CorsRoute("*","*","*")
}
}
以下是我开始路线的方法:
class RestApiRoutes : Route() {
fun init() {
get("/test") {
req, res -> {
val obj = JsonObject().addProperty("foo", "bar")
Gson().toJson(obj).toString()
}
}
}
}
当我前往http://127.0.0.1:4567/test
时,我收到:
() - > kotlin.String
为什么页面返回此而不是我预期的JSON响应?
因为
{
req, res -> {
val obj = JsonObject().addProperty("foo", "bar")
Gson().toJson(obj).toString()
}
}
是一个lambda,它返回一个没有参数的lambda,而不是一个String
。内在的lambda的toString
返回() -> kotlin.String
。
删除内部{}
来解决问题:
{ req, res ->
val obj = JsonObject().addProperty("foo", "bar")
Gson().toJson(obj).toString()
}
(有关格式约定,请参阅https://kotlinlang.org/docs/reference/coding-conventions.html#lambda-formatting)