首先，我建议根据您的要求使用任何富文本控件（RichTextFX）。但是，如果您对使用 TextArea 非常具体，请检查以下方法。
我提供的方法可能不是正确的解决方案，也可能不适合您的确切要求。但它可以帮助您朝那个方向思考。
这是基于Highlighting Strings in JavaFX TextArea 中提供的想法（@en_Knight）。我建议先通读这个 OP，然后检查我的以下实现。
我创建了一个自定义 TextArea 控件，它的工作原理与上述 OP 中提供的相同。即，混合节点以获得所需的效果。您可以通过更改演示中组合框的值来检查不同的混合效果。我假设您可能需要 BlendMode.ADD
在您选择文本时，突出显示仍然存在。
import javafx.application.Application;
import javafx.application.Platform;
import javafx.geometry.Insets;
import javafx.scene.Group;
import javafx.scene.Node;
import javafx.scene.Scene;
import javafx.scene.control.*;
import javafx.scene.effect.BlendMode;
import javafx.scene.layout.*;
import javafx.scene.shape.Path;
import javafx.scene.shape.PathElement;
import javafx.stage.Stage;
import java.util.ArrayList;
import java.util.List;
public class CustomTextAreaDemo extends Application {
@Override
public void start(Stage stage) throws Exception {
final VBox root = new VBox();
root.setSpacing(10);
root.setPadding(new Insets(10));
final Scene sc = new Scene(root, 600, 300);
stage.setScene(sc);
stage.show();
final CustomTextArea customTextArea = new CustomTextArea();
customTextArea.setText(
"Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.");
customTextArea.setWrapText(true);
customTextArea.setStyle("-fx-font-size: 15px;");
VBox.setVgrow(customTextArea, Priority.ALWAYS);
final Button highlight = new Button("Highlight");
final TextField stF = new TextField("40");
final TextField enF = new TextField("51");
final HBox hb = new HBox(highlight, stF, enF);
hb.setSpacing(10);
highlight.setOnAction(e -> {
customTextArea.highlight(Integer.parseInt(stF.getText()), Integer.parseInt(enF.getText()));
});
final Button remove = new Button("Remove Highlight");
remove.setOnAction(e -> customTextArea.removeHighlight());
final Label lbl = new Label("Resize the window to see if the highlight is in align with text");
lbl.setStyle("-fx-font-size: 17px;-fx-font-style:italic;");
final HBox rb = new HBox(remove, lbl);
rb.setSpacing(10);
ComboBox<BlendMode> blendModes = new ComboBox<>();
blendModes.getItems().addAll(BlendMode.values());
blendModes.getSelectionModel().selectedItemProperty().addListener((obs, old, blend) -> {
customTextArea.getHighlightPath().setBlendMode(blend);
});
blendModes.getSelectionModel().select(BlendMode.ADD);
root.getChildren().addAll(hb, rb,blendModes, customTextArea);
}
public static void main(String[] args) {
Application.launch(args);
}
class CustomTextArea extends TextArea {
/**
* Start position of the highlight.
*/
private int highlightStartPos = -1;
/**
* End position of the highlight.
*/
private int highlightEndPos = -1;
/**
* Path node to act as highlight.
*/
private final Path highlightPath = new Path();
/**
* Node to keep reference of the selectionGroup node of the TextArea.
*/
private Group selectionGroup;
/**
* Node to keep reference of the all contents of the TextArea.
*/
private StackPane contentPane;
/**
* Node to keep reference of the content node.
*/
private Region textContent;
/**
* Specifies whether the selection of text is done for purpose of highlighting.
*/
private boolean highlightInProgress = false;
public CustomTextArea() {
highlightPath.setStyle("-fx-fill:red");
highlightPath.setMouseTransparent(true);
highlightPath.setManaged(false);
highlightPath.setStroke(null);
textProperty().addListener((obs, oldVal, newVal) -> removeHighlight());
widthProperty().addListener((obs, oldVal, newVal) -> {
if (highlightStartPos > -1 && highlightEndPos > -1 && selectionGroup != null) {
highlightInProgress = true;
selectRange(highlightStartPos, highlightEndPos);
}
});
}
/**
* Highlights the range of characters in the text area.
*
* @param startPos Start position of the character in the text
* @param endPos End position of the character in the text
*/
public void highlight(final int startPos, final int endPos) {
highlightStartPos = startPos;
highlightEndPos = endPos;
highlightInProgress = true;
selectRange(highlightStartPos, highlightEndPos);
}
public Path getHighlightPath() {
return highlightPath;
}
@Override
protected void layoutChildren() {
super.layoutChildren();
if (selectionGroup == null || contentPane == null) {
final Region content1 = (Region) lookup(".content");
if (content1 != null) {
// Looking for the Group node that is responsible for selection
content1
.getChildrenUnmodifiable()
.stream()
.filter(node -> node instanceof Group)
.map(node -> (Group) node)
.filter(grp -> {
final boolean notSelectionGroup =
grp.getChildren().stream().anyMatch(node -> !(node instanceof Path));
return !notSelectionGroup;
})
.findFirst()
.ifPresent(n -> {
n.boundsInLocalProperty().addListener((obs, old, bil) -> {
if (highlightInProgress) {
updateHightlightBounds();
}
});
selectionGroup = n;
});
contentPane = (StackPane) content1.getParent();
textContent = content1;
}
}
}
/**
* Updates the highlight with the provided bounds.
*/
private void updateHightlightBounds() {
if (!selectionGroup.getChildren().isEmpty()) {
final Path p = (Path) selectionGroup.getChildren().get(0);
final List<PathElement> elements = new ArrayList<>(p.getElements());
highlightPath.getElements().clear();
highlightPath.getElements().addAll(elements);
final Node textNode = textContent.lookup(".text");
highlightPath.setLayoutX(textNode.getLayoutX());
highlightPath.setLayoutY(textNode.getLayoutY());
if (contentPane != null && !contentPane.getChildren().contains(highlightPath)) {
contentPane.getChildren().add(highlightPath);
}
highlightInProgress = false;
Platform.runLater(this::deselect);
}
}
/**
* Removes the highlight in the text area.
*/
public void removeHighlight() {
if (contentPane != null) {
contentPane.getChildren().remove(highlightPath);
}
highlightStartPos = -1;
highlightEndPos = -1;
}
}
}