java编写带界面的词法分析器

Java中可以使用JavaFX来编写带界面的词法分析器。下面是一个示例代码：

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.TextArea;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.HBox;
import javafx.stage.FileChooser;
import javafx.stage.Stage;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class LexicalAnalyzer extends Application {

    private final String KEYWORDS = "\\b(int|float|double|String|if|else|while|for|do|switch|case|break|continue|return|void)\\b";
    private final String OPERATORS = "[\\+\\-\\*/%]";
    private final String PUNCTUATION = "[\\{\\}\\(\\)\\[\\];,]";
    private final String INT_CONST = "\\b\\d+\\b";
    private final String FLOAT_CONST = "\\b\\d+\\.\\d+\\b";
    private final String STRING_CONST = "\"[^\"]*\"";
    private final String IDENTIFIER = "\\b[A-Za-z_]\\w*\\b";

    private TextArea textArea = new TextArea();
    private TextArea resultArea = new TextArea();

    @Override
    public void start(Stage primaryStage) {
        BorderPane borderPane = new BorderPane();
        HBox hbox = new HBox();
        Button btnOpen = new Button("Open");
        Button btnAnalyze = new Button("Analyze");
        hbox.getChildren().addAll(btnOpen, btnAnalyze);
        borderPane.setTop(hbox);
        borderPane.setLeft(textArea);
        borderPane.setRight(resultArea);
        Scene scene = new Scene(borderPane, 800, 600);
        primaryStage.setScene(scene);
        primaryStage.show();

        btnOpen.setOnAction(e -> {
            FileChooser fileChooser = new FileChooser();
            File file = fileChooser.showOpenDialog(primaryStage);
            if(file != null) {
                try {
                    BufferedReader reader = new BufferedReader(new FileReader(file));
                    String line;
                    while ((line = reader.readLine()) != null) {
                        textArea.appendText(line + "\n");
                    }
                    reader.close();
                } catch (IOException ex) {
                    ex.printStackTrace();
                }
            }
        });

        btnAnalyze.setOnAction(e -> {
            String text = textArea.getText();
            String[] lines = text.split("\n");
            StringBuilder resultBuilder = new StringBuilder();
            Pattern pattern = Pattern.compile(KEYWORDS + "|" + OPERATORS + "|" + PUNCTUATION + "|" + INT_CONST + "|" + FLOAT_CONST + "|" + STRING_CONST + "|" + IDENTIFIER);
            for (String line : lines) {
                Matcher matcher = pattern.matcher(line);
                while (matcher.find()) {
                    String token = matcher.group();
                    if (token.matches(KEYWORDS)) {
                        resultBuilder.append("<Keyword, " + token + ">\n");
                    } else if (token.matches(OPERATORS)) {
                        resultBuilder.append("<Operator, " + token + ">\n");
                    } else if (token.matches(PUNCTUATION)) {
                        resultBuilder.append("<Punctuation, " + token + ">\n");
                    } else if (token.matches(INT_CONST)) {
                        resultBuilder.append("<IntConst, " + token + ">\n");
                    } else if (token.matches(FLOAT_CONST)) {
                        resultBuilder.append("<FloatConst, " + token + ">\n");
                    } else if (token.matches(STRING_CONST)) {
                        resultBuilder.append("<StringConst, " + token + ">\n");
                    } else if (token.matches(IDENTIFIER)) {
                        resultBuilder.append("<Identifier, " + token + ">\n");
                    }
                }
            }
            resultArea.setText(resultBuilder.toString());
        });
    }

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

这个程序使用JavaFX来创建界面，其中包含一个文本框和一个按钮。用户可以在文本框中输入代码，点击按钮后程序将分析代码并在另一个文本框中输出结果。程序使用正则表达式来识别代码中的关键字、运算符、标点符号、常量和标识符，并将它们转换成相应的词法单元。