试图处理引号的简单ANTLR语法问题

grammar QuoteGrammar;

quote: '"' content '"';
content: ~["]*;

import org.antlr.v4.runtime.*;
import org.antlr.v4.runtime.tree.*;

public class QuoteParser {
    public static void main(String[] args) throws Exception {
        String input = "\"Hello, World!\"";
        QuoteGrammarLexer lexer = new QuoteGrammarLexer(CharStreams.fromString(input));
        CommonTokenStream tokens = new CommonTokenStream(lexer);
        QuoteGrammarParser parser = new QuoteGrammarParser(tokens);
        ParseTree tree = parser.quote();
        String content = tree.getChild(1).getText();
        System.out.println(content);
    }
}