通过 JavaFX UI Controller 事件,我想暂停后台服务,即以该 UI Controller 启动的服务(如以下代码所示)。
我发现了类似的帖子 JavaFX2: Can I pause a background Task / Service 。但在那篇文章中,它将提供使用其自己的事件暂停服务的解决方案,而不是使用外部 UI Controller 触发的事件。
实际上在这种情况下,我似乎必须设置服务的内部状态以使其暂停,但工作器接口(interface)不包含这样的状态。举个例子,我们可以强制服务失败,包括 FAILED 状态等。
谢谢。
UI Controller 类
public class CommandController implements Initializable {
private CommandService commandService;
private ExecutorService sequentialServiceExecutor;
private List<IOCommandService> servicePool = new ArrayList<>();
@Override
public void initialize(URL location, Resources resources) {
doProceedInitialSteps();
}
private void doProceedInitialSteps() {
// Select available IOCommands
List<IOCommand> commandList = commandService.getCommands();
// Initialised ExecutorService on sequential manner
sequentialServiceExecutor = Executors.newFixedThreadPool(
1,
new ServiceThreadFactory()
);
for (final IOCommand command : commandList) {
IOCommandService service = new IOCommandService(command, this);
service.setExecutor(sequentialServiceExecutor);
service.setOnRunning(new EventHandler<IOCommand>() { }
service.setOnSucceeded(new EventHandler<IOCommand>() { }
service.setOnFailed(new EventHandler<IOCommand>() { }
service.start();
servicePool.add(service);
}
}
@FXML
public void onCancel() {
// TODO: Need to pause current executing IOCommandService until receive the user response from the DialogBox
// Unless pause current executing IOCommandService, that will over lap this dialog box with IOCommandService related dialog boxes etc
Dialogs.DialogResponse response = Dialogs.showWarningDialog();
if(response.toString.equals("OK") {
}
}
}
服务等级
public class IOCommandService extends Service<IOCommand> {
private IOCommand command;
private CommandController controller;
public IOCommandService (IOCommand command, CommandController controller) {
this.command = command;
this.controller = controller;
}
@Override
protected Task<IOCommand> createTask() {
return new Task<IOCommand>() {
@Override
protected Integer call() throws Exception {
// Execute the IO command by,
// 1) updating some UI components (label, images etc) on CommandController
// 2) make enable popup some Dialog boxes for get user response
return command;
}
}
}
}
最佳答案
海吉·查纳,
这里是一个示例,说明如何“暂停”Service
并在关闭Dialog
后恢复它。
这是 FXML ;)
<?xml version="1.0" encoding="UTF-8"?>
<?import java.lang.*?>
<?import java.util.*?>
<?import javafx.scene.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>
<AnchorPane id="AnchorPane" prefHeight="200" prefWidth="320" xmlns:fx="http://javafx.com/fxml" fx:controller="de.professional_webworkx.stopservice.FXMLController">
<children>
<Button layoutX="126" layoutY="90" text="Click Me!" onAction="#handleButtonAction" fx:id="button" />
<Label layoutX="126" layoutY="120" minHeight="16" minWidth="69" fx:id="label" />
</children>
</AnchorPane>
主应用程序
import javafx.application.Application;
import static javafx.application.Application.launch;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;
public class MainApp extends Application {
@Override
public void start(Stage stage) throws Exception {
Parent root = FXMLLoader.load(getClass().getResource("/fxml/Scene.fxml"));
Scene scene = new Scene(root);
stage.setTitle("JavaFX and Concurrency");
stage.setScene(scene);
stage.show();
}
public static void main(String[] args) {
launch(args);
}
}
Controller
import java.net.URL;
import java.util.ResourceBundle;
import javafx.application.Platform;
import javafx.concurrent.Worker;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.stage.Stage;
public class FXMLController implements Initializable {
@FXML
private Label label;
private MyService ms;
@FXML
private void handleButtonAction(ActionEvent event) {
onCancel();
}
@Override
public void initialize(URL url, ResourceBundle rb) {
ms = new MyService();
Platform.runLater(() -> {
ms.start();
});
}
public void onCancel() {
if(ms.getState().equals(Worker.State.RUNNING)) {
ms.cancel();
}
Scene s = new Scene(new Label("Dialog"), 640, 480);
Stage dialog = new Stage();
dialog.setScene(s);
dialog.showAndWait();
if(!dialog.isShowing()) {
ms.resume();
}
}
}
以及 MyService 类
我在控制台上运行 for 循环并打印出数字。如果我调用 MyService
的 pause()
方法,我会 cancel()
并在调用 resume()
方法。
Thread.sleep(2000L);我添加只是为了模拟长时间运行的任务。
import javafx.concurrent.ScheduledService;
import javafx.concurrent.Service;
import javafx.concurrent.Task;
/**
*
* @author Patrick Ott
* @version 1.0
*/
public class MyService extends ScheduledService<Void> {
Task<Void> task;
int n = 1000000000;
@Override
protected Task<Void> createTask() {
return new Task() {
@Override
protected Object call() throws Exception {
for (int i = 0; i < n; i++) {
System.out.println("Halllo " + n);
Thread.sleep(2000);
n--;
}
return null;
}
};
}
public void pause() {
this.cancel();
}
public void resume() {
System.out.println("n="+n);
this.restart();
}
}
帕特里克
关于JavaFX - 如何使用 UI Controller 事件暂停后台服务?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/25027835/