如何控制DateFormat返回的月份和日期名称的大小写？

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;

public class DateFormatExample {
    public static void main(String[] args) {
        Date date = new Date();
        DateFormat df = new SimpleDateFormat("MMMM d, yyyy", Locale.ENGLISH);
        String formattedDate = df.format(date);
        System.out.println(formattedDate);
    }
}

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;

public class DateFormatExample {
    public static void main(String[] args) {
        Date date = new Date();
        DateFormat df = new SimpleDateFormat("MMMM d, yyyy", Locale.ENGLISH);
        String formattedDate = df.format(date);
        String upperCaseDate = formattedDate.toUpperCase();
        String lowerCaseDate = formattedDate.toLowerCase();
        System.out.println("Upper case: " + upperCaseDate);
        System.out.println("Lower case: " + lowerCaseDate);
    }
}