JavaFX：在运行时更改应用程序语言

Question

我正在使用FXML中描述的核心组件制作JavaFX桌面应用程序，我想为用户提供更改语言的选项。但是，一旦从FXML加载了组件，我还没有找到任何直接的方法来更改语言。

问题是，有什么标准方法可以处理JavaFX中的语言切换。

Answer 1

你可以做这样的事情。正如您在回答中一样，您可能希望将其实现为单例，或者使用DI框架在需要的地方注入单个实例：

public class ObservableResourceFactory {

    private ObjectProperty<ResourceBundle> resources = new SimpleObjectProperty<>();
    public ObjectProperty<ResourceBundle> resourcesProperty() {
        return resources ;
    }
    public final ResourceBundle getResources() {
        return resourcesProperty().get();
    }
    public final void setResources(ResourceBundle resources) {
        resourcesProperty().set(resources);
    }

    public StringBinding getStringBinding(String key) {
        return new StringBinding() {
            { bind(resourcesProperty()); }
            @Override
            public String computeValue() {
                return getResources().getString(key);
            }
        };
    }
}

现在，您可以执行以下操作：

ObservableResourceFactory resourceFactory = .... ;

resourceBundle.setResources(...);

Label greetingLabel = new Label();
greetingLabel.textProperty().bind(resourceFactory.getStringBinding("greeting"));

而且任何时候您使用

resourceFactory.setResources(...);

将导致标签更新其文本。

这是一个SSCCE（对将a强制ResourceBundle为单个可运行类的极其丑陋的方式表示歉意…）

import java.util.ListResourceBundle;
import java.util.Locale;
import java.util.ResourceBundle;

import javafx.application.Application;
import javafx.beans.binding.StringBinding;
import javafx.beans.property.ObjectProperty;
import javafx.beans.property.SimpleObjectProperty;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.ComboBox;
import javafx.scene.control.Label;
import javafx.scene.control.ListCell;
import javafx.scene.layout.BorderPane;
import javafx.stage.Stage;

public class ResourceBundleBindingExample extends Application {

    private static final String RESOURCE_NAME = Resources.class.getTypeName() ;

    private static final ObservableResourceFactory RESOURCE_FACTORY = new ObservableResourceFactory();

    static {
        RESOURCE_FACTORY.setResources(ResourceBundle.getBundle(RESOURCE_NAME));
    }

    @Override
    public void start(Stage primaryStage) {
        ComboBox<Locale> languageSelect = new ComboBox<>();
        languageSelect.getItems().addAll(Locale.ENGLISH, Locale.FRENCH);
        languageSelect.setValue(Locale.ENGLISH);
        languageSelect.setCellFactory(lv -> new LocaleCell());
        languageSelect.setButtonCell(new LocaleCell());

        languageSelect.valueProperty().addListener((obs, oldValue, newValue) -> {
            if (newValue != null) {
                RESOURCE_FACTORY.setResources(ResourceBundle.getBundle(RESOURCE_NAME, newValue));
            }
        });

        Label label = new Label();
        label.textProperty().bind(RESOURCE_FACTORY.getStringBinding("greeting"));

        BorderPane root = new BorderPane(null, languageSelect, null, label, null);
        root.setPadding(new Insets(10));
        Scene scene = new Scene(root, 400, 400);
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    public static class LocaleCell extends ListCell<Locale> {
        @Override
        public void updateItem(Locale locale, boolean empty) {
            super.updateItem(locale, empty);
            if (empty) {
                setText(null);
            } else {
                setText(locale.getDisplayLanguage(locale));
            }
        }
    }

    public static class ObservableResourceFactory {

        private ObjectProperty<ResourceBundle> resources = new SimpleObjectProperty<>();
        public ObjectProperty<ResourceBundle> resourcesProperty() {
            return resources ;
        }
        public final ResourceBundle getResources() {
            return resourcesProperty().get();
        }
        public final void setResources(ResourceBundle resources) {
            resourcesProperty().set(resources);
        }

        public StringBinding getStringBinding(String key) {
            return new StringBinding() {
                { bind(resourcesProperty()); }
                @Override
                public String computeValue() {
                    return getResources().getString(key);
                }
            };
        }

    }

    public static class Resources extends ListResourceBundle {

        @Override
        protected Object[][] getContents() {
            return new Object[][] {
                    {"greeting", "Hello"}
            };
        }

    }

    public static class Resources_fr extends ListResourceBundle {

        @Override
        protected Object[][] getContents() {
            return new Object[][] {
                    {"greeting", "Bonjour"}
            };
        }

    }

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