JavaFX多次运行线程

我创建了一个食品订购系统，当按下按钮时，它将调用一个方法，然后查询数据库以找出当前数量，然后查询另一个表以找出数量每道菜需要，然后用新数量更新数据库。这需要一两秒钟的时间，所以我想在用户每次订购一个项目时在新的线程上运行它，以便在每次按下按钮后都不会挂起。我试图用executorService，但我仍然得到一个InvocationTargetException错误。JavaFX多次运行线程

下面是代码：

public ExecutorService executorService = Executors.newSingleThreadExecutor(); 

Task<Boolean> buyDish = new Task<Boolean>() { 
    @Override 
    protected Boolean call() throws Exception { 
     return Datasource.getInstance().insertDishSale(dishId, cost); 
    } 
}; 

public void orderFood(ActionEvent event){ 
    if (event.getSource() == salmon) { 
     dishId = 1; 
     cost = 4.99; 
     executorService.execute(buyDish); 
    } 
}

我的问题是;

如何在数据库更新完成时运行此方法并且不会导致应用程序挂起？
在另一个线程上这样做是一个好主意，因为我只是在想，如果另一个线程试图更新数据库，它将处理的数据不是最新的，直到所有其他线程都有也更新了数据库。

编辑 -

Exception in thread "JavaFX Application Thread" java.lang.RuntimeException: java.lang.reflect.InvocationTargetException 
at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1774) 
at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1657) 
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86) 
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238) 
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191) 
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59) 
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58) 
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) 
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56) 
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) 
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56) 
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) 
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74) 
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49) 
at javafx.event.Event.fireEvent(Event.java:198) 
at javafx.scene.Node.fireEvent(Node.java:8413) 
at javafx.scene.control.Button.fire(Button.java:185) 
at com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(ButtonBehavior.java:182) 
at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:96) 
at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:89) 
at com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:218) 
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80) 
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238) 
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191) 
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59) 
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58) 
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) 
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56) 
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) 
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56) 
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) 
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74) 
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54) 
at javafx.event.Event.fireEvent(Event.java:198) 
at javafx.scene.Scene$MouseHandler.process(Scene.java:3757) 
at javafx.scene.Scene$MouseHandler.access$1500(Scene.java:3485) 
at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1762) 
at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2494) 
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:381) 
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:295) 
at java.security.AccessController.doPrivileged(Native Method) 
at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$354(GlassViewEventHandler.java:417) 
at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:389) 
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:416) 
at com.sun.glass.ui.View.handleMouseEvent(View.java:555) 
at com.sun.glass.ui.View.notifyMouse(View.java:937) 
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method) 
at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191) 
at java.lang.Thread.run(Thread.java:745) 

Caused by: java.lang.reflect.InvocationTargetException 
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) 
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
at java.lang.reflect.Method.invoke(Method.java:498) 
at sun.reflect.misc.Trampoline.invoke(MethodUtil.java:71) 
at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source) 
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
at java.lang.reflect.Method.invoke(Method.java:498) 
at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:275) 
at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1769) 
... 48 more 

Caused by: java.util.concurrent.RejectedExecutionException: Task [email protected] rejected from [email protected][Terminated, pool size = 0, active threads = 0, queued tasks = 0, completed tasks = 1] 
at java.util.concurrent.ThreadPoolExecutor$AbortPolicy.rejectedExecution(ThreadPoolExecutor.java:2047) 
at java.util.concurrent.ThreadPoolExecutor.reject(ThreadPoolExecutor.java:823) 
at java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:1369) 
at java.util.concurrent.Executors$DelegatedExecutorService.execute(Executors.java:668) 
at com.lukedavies.controller.TestController.orderFood(TestController.java:44)

来源

2017-09-13 Johnny B.

堆栈跟踪看起来像您试图在执行程序服务关闭后执行任务。 –

就是这样，在那种方法中还有其他不相干的东西，我遗漏了（这是重复的），我错过了方法结束时的关闭。我应该什么时候关闭执行器服务？ –

关闭应用程序时（例如，从Application.stop（）方法）关闭执行程序服务。 –

堆栈跟踪表明您要执行任务，你已经关闭了执行售后服务。您通常只应在退出应用程序时关闭执行程序服务，例如

public class MyApplication extends Application { 

    private ExecutorService executorService = Executors.newSingleThreadExecutor(); 

    @Override 
    public void start(Stage primaryStage) { 
     // ... 
    } 

    @Override 
    public void stop() { 
     executorService.shutdown(); 
    } 
}

或者，如果你正在使用FXML和控制器：

public class MainController { 

    private ExecutorService executorService = Executors.newSingleThreadExecutor(); 

    public void shutdown() { 
     executorService.shutdown(); 
    } 
}

和

public class MyApplication extends Application { 

    private MainController mainController ; 

    @Override 
    public void start(Stage primaryStage) { 
     FXMLLoader loader = new FXMLLoader(...); 
     Parent root = loader.load(); 
     mainController = loader.getController(); 

     // ... 

    } 

    @Override 
    public void stop() { 
     mainController.shutdown(); 
    } 
}

此外，作为documentation

与FutureTask指出，一个任务是一次性课程，不能是r eused。

（顺便说一句，请注意，它也是一个非常糟糕的主意引用在不同的线程可变数据。你dishId和cost似乎是同时从FX应用程序线程和后台线程引用的实例字段。）

因此，您不能多次使用相同的Task。每次只需创建一个新的文件：

private ExecutorService executorService = Executors.newSingleThreadExecutor(); 

private Task<Boolean> createBuyDishTask(int dishId, double cost) { 
    return new Task<Boolean>() { 
     @Override 
     protected Boolean call() throws Exception { 
      return Datasource.getInstance().insertDishSale(dishId, cost); 
     } 
    }; 
} 

public void orderFood(ActionEvent event){ 
    if (event.getSource() == salmon) { 
     executorService.execute(createBuyDishTask(1, 4.99)); 
    } 
}

来源

2017-09-13 18:13:47

复制了确切的代码并仍然得到相同的错误 - 线程“JavaFX Application Thread”中的异常java.lang.RuntimeException：java.lang.reflect.InvocationTargetException –

@JohnnyB。在你的问题中发布完整的堆栈跟踪（不只是错误消息）。 –

JavaFX多次运行线程

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