Play Framework 2.5 JavaAsync抛出CompletionException
作者：互联网
我正在使用Play 2.5构建一个简单的应用程序.为了获得更好的性能,我使用了Akka chunked响应和Java 8 CompletionStage策略.下面是生成分块响应的代码(不使用ComperableFuture时工作正常)：
@Singleton
public class AbstractSource {
public Source<ByteString, ?> getChunked(String html) {
return Source.<ByteString>actorRef(256, OverflowStrategy.dropNew())
.mapMaterializedValue(sourceActor -> {
sourceActor.tell(ByteString.fromString(html), null);
sourceActor.tell(new Status.Success(NotUsed.getInstance()), null);
return null;
});
}
}
这是我的控制器：
@Singleton
@AddCSRFToken
public class Application extends Controller {
@Inject
private AbstractSource abstractSource;
public CompletionStage<Result> index() {
CompletionStage<Source<ByteString, ?>> source = CompletableFuture.supplyAsync(() ->
abstractSource.getChunked(index.render(CSRF.getToken(request()).map(t ->
t.value()).orElse("no token")).body()
)
);
return source.thenApply( chunks -> ok().chunked(chunks));
}
}
现在,当我运行应用程序时,它会抛出以下异常：
play.api.http.HttpErrorHandlerExceptions$$anon$1: Execution exception[[CompletionException: java.lang.RuntimeException: There is no HTTP Context available from here.]]
at play.api.http.HttpErrorHandlerExceptions$.throwableToUsefulException(HttpErrorHandler.scala:269)
at play.api.http.DefaultHttpErrorHandler.onServerError(HttpErrorHandler.scala:195)
at play.api.GlobalSettings$class.onError(GlobalSettings.scala:160)
at play.api.DefaultGlobal$.onError(GlobalSettings.scala:188)
at play.api.http.GlobalSettingsHttpErrorHandler.onServerError(HttpErrorHandler.scala:98)
at play.core.server.netty.PlayRequestHandler$$anonfun$2$$anonfun$apply$1.applyOrElse(PlayRequestHandler.scala:99)
at play.core.server.netty.PlayRequestHandler$$anonfun$2$$anonfun$apply$1.applyOrElse(PlayRequestHandler.scala:98)
at scala.concurrent.Future$$anonfun$recoverWith$1.apply(Future.scala:344)
at scala.concurrent.Future$$anonfun$recoverWith$1.apply(Future.scala:343)
at scala.concurrent.impl.CallbackRunnable.run(Promise.scala:32)
Caused by: java.util.concurrent.CompletionException: java.lang.RuntimeException: There is no HTTP Context available from here.
at java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:273)
at java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:280)
at java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1592)
at java.util.concurrent.CompletableFuture$AsyncSupply.exec(CompletableFuture.java:1582)
at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289)
at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056)
at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692)
at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157)
Caused by: java.lang.RuntimeException: There is no HTTP Context available from here.
at play.mvc.Http$Context.current(Http.java:57)
at play.mvc.Controller.request(Controller.java:36)
at com.mabsisa.ui.web.controllers.Application.lambda$index$1(Application.java:31)
at java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1590)
... 5 common frames omitted
我没有在任何地方使用HTTP上下文,所以为什么这不起作用我没有得到.使用分块响应返回正常结果时,相同的代码正在运行.请帮忙
解决方法:
在处理CompletableFuture / CompletionStage时,您必须提供HTTP执行上下文.在Scala中,上下文信息通过implicits传递,这些在Java中不可用 – 这就是Play使用ThreadLocal的原因.
但是,在切换线程时,您可能会丢失此信息,这就是您遇到问题的原因.您可能认为您不访问HTTP上下文,但实际上您正在使用request().
因此,您必须更改代码以将SupplyAsync与Executor一起使用：
由此：
CompletableFuture.supplyAsync(() -> abstractSource.getChunked(index.render(CSRF.getToken(request()).map(t ->
t.value()).orElse("no token")).body()
)
);
对此：
CompletableFuture.supplyAsync(() -> abstractSource.getChunked(index.render(CSRF.getToken(request()).map(t ->
t.value()).orElse("no token")).body()
)
, ec.current());
其中ec是你的上下文：@Inject HttpExecutionContext ec;
标签：java,sbt,playframework,playframework-2-0 来源： https://codeday.me/bug/20191001/1838838.html