Play 框架 Mailer 在 maile.send() 方法中抛出 NullPointerException [英] Play framework Mailer throwing NullPointerException at maile.send() method

问题描述

我正在使用 play Mailer 模块.我在 ma​​ilerClient.send(email) 处收到 NullPointerException.

I am using play Mailer module. I am getting NullPointerException at mailerClient.send(email).

发送邮件代码

import javax.inject.Inject;
import play.libs.mailer.Email;
import play.libs.mailer.MailerClient;
public class MailerService {
    @Inject MailerClient mailerClient;
    public void sendEmail() {
        Email email = new Email();
        email.setSubject("Activation Link");
        email.setFrom("[e-mail]");
        email.addTo("[e-mail]");
        email.setBodyText("hello");
        mailerClient.send(email);
    }
}

application.conf

 # Logger provided to your application:
logger.application=DEBUG
play{
  modules {
    enabled += "play.api.libs.mailer.MailerModule"
    #enabled += "play.api.libs.mailer.SMTPConfigurationModule"
  }
  mailer {
  host=smtp.gmail.com
  port=465
  ssl=yes
  tls=no
  user="my gmail username"
  password="gmail password"
  debug=yes
}
}

我还在 build.sbt 中添加了 "com.typesafe.play" %% "play-mailer" % "3.0.1"

Also i have added "com.typesafe.play" %% "play-mailer" % "3.0.1" in build.sbt

播放版本:- 2.4

Java 版本:1.8

java version: 1.8

我正在添加堆栈跟踪

play.api.http.HttpErrorHandlerExceptions$$anon$1: Execution exception[[NullPointerException: null]]
    at play.api.http.HttpErrorHandlerExceptions$.throwableToUsefulException(HttpErrorHandler.scala:265) ~[play_2.11-2.4.6.jar:2.4.6]
    at play.api.http.DefaultHttpErrorHandler.onServerError(HttpErrorHandler.scala:191) ~[play_2.11-2.4.6.jar:2.4.6]
    at play.api.GlobalSettings$class.onError(GlobalSettings.scala:179) [play_2.11-2.4.6.jar:2.4.6]
    at play.api.DefaultGlobal$.onError(GlobalSettings.scala:212) [play_2.11-2.4.6.jar:2.4.6]
    at play.api.http.GlobalSettingsHttpErrorHandler.onServerError(HttpErrorHandler.scala:94) [play_2.11-2.4.6.jar:2.4.6]
    at play.core.server.netty.PlayDefaultUpstreamHandler$$anonfun$9$$anonfun$apply$1.applyOrElse(PlayDefaultUpstreamHandler.scala:151) [play-netty-server_2.11-2.4.6.jar:2.4.6]
    at play.core.server.netty.PlayDefaultUpstreamHandler$$anonfun$9$$anonfun$apply$1.applyOrElse(PlayDefaultUpstreamHandler.scala:148) [play-netty-server_2.11-2.4.6.jar:2.4.6]
    at scala.runtime.AbstractPartialFunction.apply(AbstractPartialFunction.scala:36) [scala-library-2.11.6.jar:na]
    at scala.util.Failure$$anonfun$recover$1.apply(Try.scala:215) [scala-library-2.11.6.jar:na]
    at scala.util.Try$.apply(Try.scala:191) [scala-library-2.11.6.jar:na]
    at scala.util.Failure.recover(Try.scala:215) [scala-library-2.11.6.jar:na]
    at scala.concurrent.Future$$anonfun$recover$1.apply(Future.scala:324) [scala-library-2.11.6.jar:na]
    at scala.concurrent.Future$$anonfun$recover$1.apply(Future.scala:324) [scala-library-2.11.6.jar:na]
    at scala.concurrent.impl.CallbackRunnable.run(Promise.scala:32) [scala-library-2.11.6.jar:na]
    at play.api.libs.iteratee.Execution$trampoline$.executeScheduled(Execution.scala:109) [play-iteratees_2.11-2.4.6.jar:2.4.6]
    at play.api.libs.iteratee.Execution$trampoline$.execute(Execution.scala:71) [play-iteratees_2.11-2.4.6.jar:2.4.6]
    at scala.concurrent.impl.CallbackRunnable.executeWithValue(Promise.scala:40) [scala-library-2.11.6.jar:na]
    at scala.concurrent.impl.Promise$DefaultPromise.tryComplete(Promise.scala:248) [scala-library-2.11.6.jar:na]
    at scala.concurrent.Promise$class.complete(Promise.scala:55) [scala-library-2.11.6.jar:na]
    at scala.concurrent.impl.Promise$DefaultPromise.complete(Promise.scala:153) [scala-library-2.11.6.jar:na]
    at scala.concurrent.impl.Future$PromiseCompletingRunnable.run(Future.scala:23) [scala-library-2.11.6.jar:na]
    at akka.dispatch.TaskInvocation.run(AbstractDispatcher.scala:40) [akka-actor_2.11-2.3.13.jar:na]
    at akka.dispatch.ForkJoinExecutorConfigurator$AkkaForkJoinTask.exec(AbstractDispatcher.scala:397) [akka-actor_2.11-2.3.13.jar:na]
    at scala.concurrent.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260) [scala-library-2.11.6.jar:na]
    at scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1339) [scala-library-2.11.6.jar:na]
    at scala.concurrent.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979) [scala-library-2.11.6.jar:na]
    at scala.concurrent.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107) [scala-library-2.11.6.jar:na]

**Caused by: java.lang.NullPointerException: null**
    at mailer.MailerService.sendEmail(MailerService.java:17) ~[classes/:na]
    at controllers.Application.sendMailTest(Application.java:14) ~[classes/:na]
    at router.Routes$$anonfun$routes$1$$anonfun$applyOrElse$10$$anonfun$apply$10.apply(Routes.scala:324) ~[classes/:na]
    at router.Routes$$anonfun$routes$1$$anonfun$applyOrElse$10$$anonfun$apply$10.apply(Routes.scala:324) ~[classes/:na]
    at play.core.routing.HandlerInvokerFactory$$anon$4.resultCall(HandlerInvoker.scala:136) ~[play_2.11-2.4.6.jar:2.4.6]
    at play.core.routing.HandlerInvokerFactory$JavaActionInvokerFactory$$anon$14$$anon$3$$anon$1.invocation(HandlerInvoker.scala:127) ~[play_2.11-2.4.6.jar:2.4.6]
    at play.core.j.JavaAction$$anon$1.call(JavaAction.scala:70) ~[play_2.11-2.4.6.jar:2.4.6]

推荐答案

您似乎错误地初始化了 MailerClient.

It looks like you incorrectly initialize MailerClient.

示例 表明您需要将其注入控制器，控制器本身由播放框架.

The example shows that you need to inject it into the controller, that itself initialized by the Play Framework.

您将其注入到您自己的 MailerService 类中.我想您在 controllers.Application.sendMailTest 中执行了类似 new MailerService() 的操作.因此，MailerClient 不会注入到 MailerService 类中(如果您自己初始化 MailerService，谁会这样做?)

You inject it into your own MailerService class. I suppose that you do something like new MailerService() in the controllers.Application.sendMailTest. As a result, MailerClient does not inject into the MailerService class (Who will do this if you initialise MailerService yourself ?)

解决办法:您需要像示例中那样将 MailerClient 注入控制器，然后将其传递到您的 MailerService 类中.

Solution: You need to inject MailerClient into the controller, like in the example, and then pass it into your MailerService class.

import play.libs.mailer.Email;
import play.libs.mailer.MailerClient;
public class MailerService {
  MailerClient mailerClient;

  public MailerService(MailerClient mailerClient){
    this.mailerClient = mailerClient;
  }

  public void sendEmail() {
    Email email = new Email();
    email.setSubject("Activation Link");
    email.setFrom("[e-mail]");
    email.addTo("[e-mail]");
    email.setBodyText("hello");
    mailerClient.send(email);
  }
}

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