通过使用简单的自定义日志记录框架的线程将消息记录到JavaFX TextArea的最有效方法

Question

我有一个简单的自定义日志框架，如下所示：

package something;

import javafx.scene.control.TextArea;

public class MyLogger {
    public final TextArea textArea;

    private boolean verboseMode = false;
    private boolean debugMode = false;

    public MyLogger(final TextArea textArea) {
        this.textArea = textArea;
    }

    public MyLogger setVerboseMode(boolean value) {
        verboseMode = value;
        return this;
    }

    public MyLogger setDebugMode(boolean value) {
        debugMode = value;
        return this;
    }

    public boolean writeMessage(String msg) {
        textArea.appendText(msg);
        return true;
    }

    public boolean logMessage(String msg) {
        return writeMessage(msg + "\n");
    }

    public boolean logWarning(String msg) {
        return writeMessage("Warning: " + msg + "\n");
    }

    public boolean logError(String msg) {
        return writeMessage("Error: " + msg + "\n");
    }

    public boolean logVerbose(String msg) {
        return verboseMode ? writeMessage(msg + "\n") : true;
    }

    public boolean logDebug(String msg) {
        return debugMode ? writeMessage("[DEBUG] " + msg + "\n") : true;
    }
}

现在我要做的是扩展它，使它能够正确地处理通过线程记录消息。我尝试过一些解决方案，比如使用带有AnimationTimer的消息队列。它可以工作，但会减慢GUI的速度。

我已经试着查阅了其他已知的日志记录框架解决方案，比如log4j和这里提到的一些工具，但它们似乎都没有给出通过线程到textarea进行日志记录的明显方法。我也不喜欢在它们上面构建日志系统的想法，因为它们已经有了预定义的机制，比如日志级别等。

我也见过这个。这意味着使用swingUtilities.invokelater(Runnable)来更新控件，但我已经尝试过使用javafx.application.platform.runlater()的类似方法，它在工作线程上执行。我不确定是不是我做错了什么，但它只是挂。它可以产生信息，但不是当它们足够具有攻击性时。我估计，以纯同步方式运行的工作线程实际上可以每秒产生大约20或更多的平均行，当它处于调试模式时更多。一个可能的解决办法是将消息队列也添加到它中，但这已经没有意义了。

Answer 1

日志-视图.css

.root {
    -fx-padding: 10px;
}

.log-view .list-cell {
    -fx-background-color: null; // removes alternating list gray cells.
}

.log-view .list-cell:debug {
    -fx-text-fill: gray;
}

.log-view .list-cell:info {
    -fx-text-fill: green;
}

.log-view .list-cell:warn {
    -fx-text-fill: purple;
}

.log-view .list-cell:error {
    -fx-text-fill: red;
}

LogViewer.java

import javafx.animation.Animation;
import javafx.animation.KeyFrame;
import javafx.animation.Timeline;
import javafx.application.Application;
import javafx.beans.binding.Bindings;
import javafx.beans.property.*;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.collections.transformation.FilteredList;
import javafx.css.PseudoClass;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.*;
import javafx.scene.layout.HBox;
import javafx.scene.layout.Priority;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
import javafx.util.Duration;

import java.text.SimpleDateFormat;
import java.util.Collection;
import java.util.Date;
import java.util.Random;
import java.util.concurrent.BlockingDeque;
import java.util.concurrent.LinkedBlockingDeque;

class Log {
    private static final int MAX_LOG_ENTRIES = 1_000_000;

    private final BlockingDeque<LogRecord> log = new LinkedBlockingDeque<>(MAX_LOG_ENTRIES);

    public void drainTo(Collection<? super LogRecord> collection) {
        log.drainTo(collection);
    }

    public void offer(LogRecord record) {
        log.offer(record);
    }
}

class Logger {
    private final Log log;
    private final String context;

    public Logger(Log log, String context) {
        this.log = log;
        this.context = context;
    }

    public void log(LogRecord record) {
        log.offer(record);
    }

    public void debug(String msg) {
        log(new LogRecord(Level.DEBUG, context, msg));
    }

    public void info(String msg) {
        log(new LogRecord(Level.INFO, context, msg));
    }

    public void warn(String msg) {
        log(new LogRecord(Level.WARN, context, msg));
    }

    public void error(String msg) {
        log(new LogRecord(Level.ERROR, context, msg));
    }

    public Log getLog() {
        return log;
    }
}

enum Level { DEBUG, INFO, WARN, ERROR }

class LogRecord {
    private Date   timestamp;
    private Level  level;
    private String context;
    private String message;

    public LogRecord(Level level, String context, String message) {
        this.timestamp = new Date();
        this.level     = level;
        this.context   = context;
        this.message   = message;
    }

    public Date getTimestamp() {
        return timestamp;
    }

    public Level getLevel() {
        return level;
    }

    public String getContext() {
        return context;
    }

    public String getMessage() {
        return message;
    }
}

class LogView extends ListView<LogRecord> {
    private static final int MAX_ENTRIES = 10_000;

    private final static PseudoClass debug = PseudoClass.getPseudoClass("debug");
    private final static PseudoClass info  = PseudoClass.getPseudoClass("info");
    private final static PseudoClass warn  = PseudoClass.getPseudoClass("warn");
    private final static PseudoClass error = PseudoClass.getPseudoClass("error");

    private final static SimpleDateFormat timestampFormatter = new SimpleDateFormat("HH:mm:ss.SSS");

    private final BooleanProperty       showTimestamp = new SimpleBooleanProperty(false);
    private final ObjectProperty<Level> filterLevel   = new SimpleObjectProperty<>(null);
    private final BooleanProperty       tail          = new SimpleBooleanProperty(false);
    private final BooleanProperty       paused        = new SimpleBooleanProperty(false);
    private final DoubleProperty        refreshRate   = new SimpleDoubleProperty(60);

    private final ObservableList<LogRecord> logItems = FXCollections.observableArrayList();

    public BooleanProperty showTimeStampProperty() {
        return showTimestamp;
    }

    public ObjectProperty<Level> filterLevelProperty() {
        return filterLevel;
    }

    public BooleanProperty tailProperty() {
        return tail;
    }

    public BooleanProperty pausedProperty() {
        return paused;
    }

    public DoubleProperty refreshRateProperty() {
        return refreshRate;
    }

    public LogView(Logger logger) {
        getStyleClass().add("log-view");

        Timeline logTransfer = new Timeline(
                new KeyFrame(
                        Duration.seconds(1),
                        event -> {
                            logger.getLog().drainTo(logItems);

                            if (logItems.size() > MAX_ENTRIES) {
                                logItems.remove(0, logItems.size() - MAX_ENTRIES);
                            }

                            if (tail.get()) {
                                scrollTo(logItems.size());
                            }
                        }
                )
        );
        logTransfer.setCycleCount(Timeline.INDEFINITE);
        logTransfer.rateProperty().bind(refreshRateProperty());

        this.pausedProperty().addListener((observable, oldValue, newValue) -> {
            if (newValue && logTransfer.getStatus() == Animation.Status.RUNNING) {
                logTransfer.pause();
            }

            if (!newValue && logTransfer.getStatus() == Animation.Status.PAUSED && getParent() != null) {
                logTransfer.play();
            }
        });

        this.parentProperty().addListener((observable, oldValue, newValue) -> {
            if (newValue == null) {
                logTransfer.pause();
            } else {
                if (!paused.get()) {
                    logTransfer.play();
                }
            }
        });

        filterLevel.addListener((observable, oldValue, newValue) -> {
            setItems(
                    new FilteredList<LogRecord>(
                            logItems,
                            logRecord ->
                                logRecord.getLevel().ordinal() >=
                                filterLevel.get().ordinal()
                    )
            );
        });
        filterLevel.set(Level.DEBUG);

        setCellFactory(param -> new ListCell<LogRecord>() {
            {
                showTimestamp.addListener(observable -> updateItem(this.getItem(), this.isEmpty()));
            }

            @Override
            protected void updateItem(LogRecord item, boolean empty) {
                super.updateItem(item, empty);

                pseudoClassStateChanged(debug, false);
                pseudoClassStateChanged(info, false);
                pseudoClassStateChanged(warn, false);
                pseudoClassStateChanged(error, false);

                if (item == null || empty) {
                    setText(null);
                    return;
                }

                String context =
                        (item.getContext() == null)
                                ? ""
                                : item.getContext() + " ";

                if (showTimestamp.get()) {
                    String timestamp =
                            (item.getTimestamp() == null)
                                    ? ""
                                    : timestampFormatter.format(item.getTimestamp()) + " ";
                    setText(timestamp + context + item.getMessage());
                } else {
                    setText(context + item.getMessage());
                }

                switch (item.getLevel()) {
                    case DEBUG:
                        pseudoClassStateChanged(debug, true);
                        break;

                    case INFO:
                        pseudoClassStateChanged(info, true);
                        break;

                    case WARN:
                        pseudoClassStateChanged(warn, true);
                        break;

                    case ERROR:
                        pseudoClassStateChanged(error, true);
                        break;
                }
            }
        });
    }
}

class Lorem {
    private static final String[] IPSUM = "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Quisque hendrerit imperdiet mi quis convallis. Pellentesque fringilla imperdiet libero, quis hendrerit lacus mollis et. Maecenas porttitor id urna id mollis. Suspendisse potenti. Cum sociis natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Cras lacus tellus, semper hendrerit arcu quis, auctor suscipit ipsum. Vestibulum venenatis ante et nulla commodo, ac ultricies purus fringilla. Aliquam lectus urna, commodo eu quam a, dapibus bibendum nisl. Aliquam blandit a nibh tincidunt aliquam. In tellus lorem, rhoncus eu magna id, ullamcorper dictum tellus. Curabitur luctus, justo a sodales gravida, purus sem iaculis est, eu ornare turpis urna vitae dolor. Nulla facilisi. Proin mattis dignissim diam, id pellentesque sem bibendum sed. Donec venenatis dolor neque, ut luctus odio elementum eget. Nunc sed orci ligula. Aliquam erat volutpat.".split(" ");
    private static final int MSG_WORDS = 8;
    private int idx = 0;

    private Random random = new Random(42);

    synchronized public String nextString() {
        int end = Math.min(idx + MSG_WORDS, IPSUM.length);

        StringBuilder result = new StringBuilder();
        for (int i = idx; i < end; i++) {
            result.append(IPSUM[i]).append(" ");
        }

        idx += MSG_WORDS;
        idx = idx % IPSUM.length;

        return result.toString();
    }

    synchronized public Level nextLevel() {
        double v = random.nextDouble();

        if (v < 0.8) {
            return Level.DEBUG;
        }

        if (v < 0.95) {
            return Level.INFO;
        }

        if (v < 0.985) {
            return Level.WARN;
        }

        return Level.ERROR;
    }

}

public class LogViewer extends Application {
    private final Random random = new Random(42);

    @Override
    public void start(Stage stage) throws Exception {
        Lorem  lorem  = new Lorem();
        Log    log    = new Log();
        Logger logger = new Logger(log, "main");

        logger.info("Hello");
        logger.warn("Don't pick up alien hitchhickers");

        for (int x = 0; x < 20; x++) {
            Thread generatorThread = new Thread(
                    () -> {
                        for (;;) {
                            logger.log(
                                    new LogRecord(
                                            lorem.nextLevel(),
                                            Thread.currentThread().getName(),
                                            lorem.nextString()
                                    )
                            );

                            try {
                                Thread.sleep(random.nextInt(1_000));
                            } catch (InterruptedException e) {
                                Thread.currentThread().interrupt();
                            }
                        }
                    },
                    "log-gen-" + x
            );
            generatorThread.setDaemon(true);
            generatorThread.start();
        }

        LogView logView = new LogView(logger);
        logView.setPrefWidth(400);

        ChoiceBox<Level> filterLevel = new ChoiceBox<>(
                FXCollections.observableArrayList(
                        Level.values()
                )
        );
        filterLevel.getSelectionModel().select(Level.DEBUG);
        logView.filterLevelProperty().bind(
                filterLevel.getSelectionModel().selectedItemProperty()
        );

        ToggleButton showTimestamp = new ToggleButton("Show Timestamp");
        logView.showTimeStampProperty().bind(showTimestamp.selectedProperty());

        ToggleButton tail = new ToggleButton("Tail");
        logView.tailProperty().bind(tail.selectedProperty());

        ToggleButton pause = new ToggleButton("Pause");
        logView.pausedProperty().bind(pause.selectedProperty());

        Slider rate = new Slider(0.1, 60, 60);
        logView.refreshRateProperty().bind(rate.valueProperty());
        Label rateLabel = new Label();
        rateLabel.textProperty().bind(Bindings.format("Update: %.2f fps", rate.valueProperty()));
        rateLabel.setStyle("-fx-font-family: monospace;");
        VBox rateLayout = new VBox(rate, rateLabel);
        rateLayout.setAlignment(Pos.CENTER);

        HBox controls = new HBox(
                10,
                filterLevel,
                showTimestamp,
                tail,
                pause,
                rateLayout
        );
        controls.setMinHeight(HBox.USE_PREF_SIZE);

        VBox layout = new VBox(
                10,
                controls,
                logView
        );
        VBox.setVgrow(logView, Priority.ALWAYS);

        Scene scene = new Scene(layout);
        scene.getStylesheets().add(
            this.getClass().getResource("log-view.css").toExternalForm()
        );
        stage.setScene(scene);
        stage.show();
    }

    public static void main(String[] args) {
        launch(args);
    }
}

下面关于可选文本的部分是对上面发布的解决方案的补充。如果不需要可选择的文本，可以忽略下面的选择。

null

尝试实现适合您的文本选择方法，如果您不能使其工作，创建一个特定于可选择文本日志的新问题，使用MCVE。