multithreading - 如何在 JavaFX 中实时更新 textarea(console) 而不会丢失流量或卡住应用程序

Question

我是新的 JFX，我正在为此苦苦挣扎。我正在尝试运行一个必须将输出(system.out 和 system.err)打印到 textarea 的简单模拟。

 public class ConsoleController {
    @FXML
    public TextArea consoleLogscreen;

    private class Console extends OutputStream {

        @Override
        public void write(int b) throws IOException {
            consoleLogscreen.appendText(String.valueOf((char) b));
        }
    }

    @FXML
    public void initialize() throws IOException {
        Console console = new Console();
        PrintStream ps = new PrintStream(console, true);
        System.setOut(ps);
        System.setErr(ps);
        System.err.flush();
        System.out.flush();
    }
}

模拟 Controller :

 public class SimulationController {
    @FXML
    private Button homebutton;
    @FXML
    private Button abortbutton;
    private volatile Service<Void> backgroundThread;
    private volatile Thread t;
    private volatile Simulate sim;
    @FXML
    public void initialize() {
        sim = new Simulate();
        t = new Thread(sim);
        backgroundThread = new Service<Void>() {
            @Override
            protected Task<Void> createTask() {
                return new Task<Void>() {
                    @Override
                    protected Void call() throws Exception {
                        t.run();
                        return null;
                    }
                };
            }
        };
        backgroundThread.setOnCancelled(new EventHandler<WorkerStateEvent>() {
            @Override
            public void handle(WorkerStateEvent event) {
                t.interrupt();
                sim.shutDown(true);
            }
        });
        backgroundThread.restart();
        abortbutton.setDisable(false);
        homebutton.setDisable(true);
    }
    @FXML
    void onAbortClicked(ActionEvent event) throws IOException {
        if (event.getSource() == abortbutton) {
            backgroundThread.cancel();
        }
    }
    @FXML
    void onHomeClicked(ActionEvent event) throws IOException {
        if (event.getSource() == homebutton) {
            Utility.getHome((Stage) homebutton.getScene().getWindow());
        }
    }
}

模拟.fxml:

<Pane prefHeight="500.0" prefWidth="750.0"xmlns="http://javafx.com/javafx/8"      xmlns:fx="http://javafx.com/fxml/1" fx:controller="com.jfxabstract.view.SimulationController">
   <children>
      <Button fx:id="abortbutton" alignment="CENTER" contentDisplay="CENTER" layoutX="250.0" layoutY="430.0" mnemonicParsing="false" onAction="#onAbortClicked" styleClass="custombutton" text="Abort" textAlignment="CENTER" />
      <Button fx:id="homebutton" alignment="CENTER" contentDisplay="CENTER" layoutX="450.0" layoutY="430.0" mnemonicParsing="false" onAction="#onHomeClicked" styleClass="custombutton" text="Home" textAlignment="CENTER" />
      <fx:include source="Console.fxml" />
   </children>
</Pane>

我正在使用 javafx.concurrent.service 来运行我的任务，但应用程序卡住并且打印输出不是实时的。

任何人都可以建议我可能哪里出错了。

提前致谢。

更新:

run 方法从数据库中检索数据并通过调用同一类中的其他方法运行少量验证。对于简单的抽象应用程序，我正在使用这个

public void run() {
    long i = 1;
    while (i < 90) {
        double k = Math.sqrt(Math.pow(i, 2) / Math.sqrt(i));
        System.out.println("i: " + i + " Count: " + k);
        if (!shutdown) {
            break;
        }
        i++;
    }
}

Answer 1

如果不想使用 Platform.runLater() 方法，可以使用表示任务(服务)结果的值属性:

consoleLogscreen.textProperty().bind(backgroundThread.valueProperty());

这是一个完整的例子:

simulation.xml

<?xml version="1.0" encoding="UTF-8"?>
<?import java.lang.*?>
<?import java.util.*?>
<?import javafx.scene.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>

<Pane prefHeight="563.0" prefWidth="750.0" xmlns="http://javafx.com/javafx/8.0.40" xmlns:fx="http://javafx.com/fxml/1" fx:controller="SimulationController">
    <children>
        <ProgressBar fx:id="progressBar" layoutX="309.0" layoutY="14.0" prefHeight="18.0" prefWidth="162.0" progress="0.0" />
        <Button fx:id="abortbutton" alignment="CENTER" contentDisplay="CENTER" layoutX="250.0" layoutY="520.0" mnemonicParsing="false" onAction="#onAbortClicked" styleClass="custombutton" text="Abort" textAlignment="CENTER" />
        <Button fx:id="homebutton" alignment="CENTER" contentDisplay="CENTER" layoutX="450.0" layoutY="520.0" mnemonicParsing="false" onAction="#onHomeClicked" styleClass="custombutton" text="Home" textAlignment="CENTER" />
        <TextArea fx:id="consoleLogscreen" layoutX="15.0" layoutY="10.0" prefHeight="487.0" prefWidth="287.0" wrapText="true" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="0.0" />
        <Label fx:id="progress" layoutX="484.0" layoutY="15.0" text="Label" />

    </children>
</Pane>

SimulationController 类

import java.net.URL;
import java.util.ResourceBundle;
import javafx.beans.binding.When;
import javafx.concurrent.Service;
import javafx.concurrent.Task;
import javafx.concurrent.WorkerStateEvent;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.ProgressBar;
import javafx.scene.control.TextArea;

/**
 * FXML Controller class
 *
 * @author 
 */
public class SimulationController implements Initializable {

    @FXML
    private Button abortbutton;
    @FXML
    private Button homebutton;

    private volatile Service<String> backgroundThread;
    @FXML
    private TextArea consoleLogscreen;
    @FXML
    private ProgressBar progressBar;
    @FXML
    private Label progress;

    /**
     * Initializes the controller class.
     */
    @Override
    public void initialize(URL url, ResourceBundle rb) {

         backgroundThread = new Service<String>() {
            @Override
            protected Task<String> createTask() {
                return new Task<String>() {
                    StringBuilder results = new StringBuilder();
                    @Override
                    protected String call() throws Exception {
                        long i = 1;
                        String s = null;
                        while (i < 90) {
                            if(isCancelled()){
                                break;
                            }
                            double k = Math.sqrt(Math.pow(i, 2) / Math.sqrt(i));
                            results.append("i: ").append(i).append(" Count: ").append(k).append("\n");
                            updateValue(results.toString());
                            updateProgress((100*i)/90, 90);
                            Thread.sleep(100);
                            i++;
                        }

                        return results.toString();
                    }
                };
            }
        };
        consoleLogscreen.textProperty().bind(backgroundThread.valueProperty());
        progressBar.progressProperty().bind(backgroundThread.progressProperty());
        progress.textProperty().bind(new When(backgroundThread.progressProperty().isEqualTo(-1)).then("Unknown")
                .otherwise(backgroundThread.progressProperty().multiply(100).asString("%.2f%%")));
        backgroundThread.start();
        backgroundThread.setOnCancelled(new EventHandler<WorkerStateEvent>() {
            @Override
            public void handle(WorkerStateEvent event) {

            }
        });
        backgroundThread.restart();
        abortbutton.setDisable(false);
        homebutton.setDisable(true);
    }

    @FXML
    private void onAbortClicked(ActionEvent event) {
        if (event.getSource() == abortbutton) {
            backgroundThread.cancel();
        }
    }

    @FXML
    private void onHomeClicked(ActionEvent event) {
    }

}