如何在java regex中获取`{`？

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Main {
    public static void main(String[] args) {
        String input = "This is a {sample} string";
        String pattern = "\\{";

        Pattern regex = Pattern.compile(pattern);
        Matcher matcher = regex.matcher(input);

        if (matcher.find()) {
            String match = matcher.group();
            System.out.println("Match: " + match);
        } else {
            System.out.println("No match found.");
        }
    }
}

Match: {