Calendar calendar = Calendar.getInstance();
calendar.setTime(new Date());  // 设置当前日期
calendar.add(Calendar.DATE, 7);  // 增加7天
Date newDate = calendar.getTime();  // 获取新日期
SimpleDateFormat df1 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String s1=df1.format(newDate);
SimpleDateFormat df2 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
try {
   Date date = df2.parse(s1);
   essayTheme.setTimeEffect(date);
} catch (ParseException e) {
   throw new RuntimeException(e);
}