java获取当前年份、月份和日期

创建一个Calendar类的实例对象，Calendar类属于java.util包
Calendar calendar = Calendar.getInstance();

获取当前年份、月份和日期

// 获取当前年
int year = calendar.get(Calendar.YEAR);
// 获取当前月
int month = calendar.get(Calendar.MONTH) + 1;
// 获取当前日
int day = calenedar.get(Calendar.DATE);
// 获取当前小时
int hour = calendar.get(Calendar.HOUR_OF_DAY);
// 获取当前分钟
int minute = calendar.get(Calendar.MINUTE);
// 获取当前秒
int second = calendar.get(Calendar.SECOND);
// 获取当前是本周第几天
int dayOfWeek = calendar.get(Calendar.DAY_OF_WEEK);
// 获取当前是本月第几天
int dayOfMonth = calendar.get(Calendar.DAY_OF_MONTH);
// 获取当前是本年第几天
int dayOfYear = calendar.get(Calendar.DAY_OF_YEAR);

获取当月的第一天和最后一天

SimpleDateFormat format = new SimpleDateFormat(“yyyy-MM-dd”);
// 获取当月第一天
calendar = Calendar.getInstance();
calendar.add(Calendar.MONTH, 0);
calendar.set(Calendar.DAY_OF_MONTH, 1);
String firstday = format.format(calendar.getTime());
// 获取当月最后一天
calendar = Calendar.getInstance();
calendar.add(Calendar.MONTH, 1);
calendar.set(Calendar.DAY_OF_MONTH, 0);
String lastday = format.format(calendar.getTime());

当前日期
SimpleDateFormat format = new SimpleDateFormat(“yyyy-MM-dd hh:mm:ss”);
Date date = new Date();
String today = format.format(date);