获取星期几的开始日期（可配置的星期几开始日期）

我使用以下方法：

public static Date getFirstDayOfWeekDate(int firstDay){    // Calculate the date of the first day of the week    // First get the today's date    Calendar c = new GregorianCalendar();    // Now set the day of week to the first day of week    while (c.get(Calendar.DAY_OF_WEEK) != firstDay)    {        c.add(Calendar.DAY_OF_MONTH, -1);    }    return c.getTime();}