java - 在 Controller 之外渲染 scala 模板？ ( Play 2)

Question

我正在尝试将通知电子邮件的发送与导致通知电子邮件的事件分离。到目前为止，我将邮件对象 (DocumentIssuedMail) 从 Controller 传递到 Akka actor(EmailDispatcher)，然后通过 Play 邮件程序插件的 play-easymail 包装器发送邮件。电子邮件正文由邮件对象在传递给参与者后生成，并且 HTML 是从 Scala 模板生成的。

此模板包含带有绝对 URL 的链接，通过调用获取

@routes.SomeController.someAction().absoluteURL()

但是，我在尝试渲染模板时遇到了 RuntimeException。

堆栈跟踪如下:

java.lang.RuntimeException: There is no HTTP Context available from here.
    at play.mvc.Http$Context.current(Http.java:30)
    at play.mvc.Http$Context$Implicit.ctx(Http.java:196)
    at play.core.j.PlayMagicForJava$.requestHeader(TemplateMagicForJava.scala:56)
    at views.html.email._learner_main$.apply(_learner_main.template.scala:41)
    at views.html.documents.email.new_doc_unregistered$.apply(new_doc_unregistered.template.scala:47)
    at views.html.documents.email.new_doc_unregistered$.render(new_doc_unregistered.template.scala:67)
    at views.html.documents.email.new_doc_unregistered.render(new_doc_unregistered.template.scala)
    at email.DocumentIssuedMail.getUnregisteredMail(DocumentIssuedMail.java:71)
    at email.DocumentIssuedMail.getMail(DocumentIssuedMail.java:67)
    at actors.email.EmailDispatcher.onReceive(EmailDispatcher.java:32)
    at akka.actor.UntypedActor$$anonfun$receive$1.applyOrElse(UntypedActor.scala:167)
    at akka.actor.ActorCell.receiveMessage(ActorCell.scala:498)
    at akka.actor.ActorCell.invoke(ActorCell.scala:456)
    at akka.dispatch.Mailbox.processMailbox(Mailbox.scala:237)
    at akka.dispatch.Mailbox.run(Mailbox.scala:219)
    at akka.dispatch.ForkJoinExecutorConfigurator$AkkaForkJoinTask.exec(AbstractDispatcher.scala:386)
    at scala.concurrent.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260)
    at scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1339)
    at scala.concurrent.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979)
    at scala.concurrent.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107)

是否可以在该位置渲染模板，或者我是否需要在原始线程上进行渲染？

Answer 1

此问题的一个可能的解决方案是将 http 请求显式传递给您的参与者，然后传递给邮件模板。

在模板中，您将此请求传递给 absoluteURL() 方法:

@(requestHeader: play.api.mvc.RequestHeader)

@main("") {
    @routes.Application.someAction().absoluteURL()(requestHeader)
}

与DocumentIssuedMail一起，您需要将请求传递给参与者。这是一个简单的 DTO。

import play.api.mvc.RequestHeader;

public class DocumentIssuedMailWrapper {
    private DocumentIssuedMail documentIssuedMail;
    private RequestHeader requestHeader;

    public DocumentIssuedMailWrapper(DocumentIssuedMail documentIssuedMail, RequestHeader requestHeader) {
        this.documentIssuedMail = documentIssuedMail;
        this.requestHeader = requestHeader;
    }

    public DocumentIssuedMail getDocumentIssuedMail() {
        return documentIssuedMail;
    }

    public RequestHeader getRequestHeader() {
        return requestHeader;
    }
}

参与者将请求作为普通参数从 DTO 传递到邮件模板。

import akka.actor.UntypedActor;
import play.api.templates.Html;
import views.html.mail;

public class EmailDispatcher extends UntypedActor {

    @Override
    public void onReceive(Object message) throws Exception {
        if (message instanceof DocumentIssuedMailWrapper) {
            DocumentIssuedMailWrapper wrapper = (DocumentIssuedMailWrapper) message;
            Html mailTemplate = mail.render(wrapper.getRequestHeader());
            //sending mail
        }
    }

}

在 Controller 中，您可以通过调用 ctx()._requestHeader() 方法来获取请求。现在您只需要与参与者安排一个工作并向 DTO 传递请求即可。

import akka.actor.ActorRef;
import akka.actor.Props;
import play.libs.Akka;
import play.mvc.*;

import scala.concurrent.duration.Duration;

import java.util.concurrent.TimeUnit;

public class Application extends Controller {

    public static Result sendMail() {
        DocumentIssuedMailWrapper wrapper = new DocumentIssuedMailWrapper(new DocumentIssuedMail(), ctx()._requestHeader());

        ActorRef emailDispatcher = Akka.system().actorOf(Props.create(EmailDispatcher.class));
        Akka.system().scheduler().scheduleOnce(Duration.create(0, TimeUnit.MILLISECONDS), emailDispatcher, wrapper, Akka.system().dispatcher(), null);
        return ok("Mail sent");
    }

    public static Result someAction() {
        return ok("Some other action");
    }

}