public class DateOrStringUtil {
    //日期转为字符串，默认yyyy-MM-dd
    public static String dateToString(Date d) {
        return dateToString(d, "yyyy-MM-dd");
    }
    //日期转为字符串，自定义格式
    public static String dateToString(Date d, String pattern) {
        SimpleDateFormat sdf = new SimpleDateFormat(pattern);
        return sdf.format(d);
    }
    //字符串转为日期，默认yyyy-MM-dd
    public static Date stringToDate(String str) {
        return stringToDate(str, "yyyy-MM-dd");
    }
    //字符串转为日期，自定义格式
    public static Date stringToDate(String str, String pattern) {
        SimpleDateFormat sdf = new SimpleDateFormat(pattern);
        try {
            Date d = sdf.parse(str);
            return d;
        } catch (ParseException e) {
            e.printStackTrace();
        }
        return new Date();
    }
}