java中Calendar类的使用

public class TestCalendar {

@Test
public void test(){
try {
Calendar calendar = new GregorianCalendar();//子类实例化
//获取年、月、日、时、分、秒、毫秒
System.out.println("年： "+calendar.get(Calendar.YEAR));
System.out.println("月 "+(calendar.get(Calendar.MONTH)+1));
System.out.println("日： "+calendar.get(Calendar.DAY_OF_MONTH));
System.out.println("时： "+calendar.get(Calendar.HOUR_OF_DAY));
System.out.println("分： "+calendar.get(Calendar.MINUTE));
System.out.println("秒： "+calendar.get(Calendar.SECOND));
System.out.println("毫秒 "+calendar.get(Calendar.MILLISECOND));

// 当前月第一天、最后一天
int currYear = calendar.get(Calendar.YEAR);
int currMonth = calendar.get(Calendar.MONTH) + 1;
System.out.print(currYear + "-" + currMonth);
SimpleDateFormat datef = new SimpleDateFormat("yyyy-MM-dd");
calendar.set(Calendar.DAY_OF_MONTH, 1);
Date beginTime = calendar.getTime();
String sTime = datef.format(beginTime) + " 00:00:00";
calendar.set(Calendar.DATE, 1);
calendar.roll(Calendar.DATE, -1);
Date endTime = calendar.getTime();
String eTime = datef.format(endTime) + " 23:59:59";
System.out.println("第一天"+sTime+"最后一天"+eTime);

Calendar cal = Calendar.getInstance();
//指定年月的的第一天、最后一天
int year = 2015;
int moth = 3;
cal.set(Calendar.YEAR,year);
cal.set(Calendar.MONTH, moth-1);
//当前月的最后一天
cal.set( Calendar.DATE, 1 );
cal.roll(Calendar.DATE, - 1 );
Date endTime2=cal.getTime();
String endTimeStr=datef.format(endTime2)+" 23:59:59";
//当前月的第一天
cal.set(GregorianCalendar.DAY_OF_MONTH, 1);
Date beginTime2=cal.getTime();
String beginTimeStr=datef.format(beginTime2)+" 00:00:00";

System.out.println("指定年月的的第一天"+endTimeStr+"最后一天"+beginTimeStr);

//当前时间的前一天
SimpleDateFormat sdf2 = new SimpleDateFormat("yyyy-MM-dd:HH");
String tmStr = "2015-5-18:00";
Date d = sdf2.parse(tmStr);
System.out.println(d);
Calendar now = Calendar.getInstance();
now.setTime(d);
now.set(Calendar.HOUR, now.get(Calendar.HOUR) -1);
System.out.println(sdf2.format(now.getTime()));

//最近N天
SimpleDateFormat df2 = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
cal.add(Calendar.DATE,-7);
System.out.println("最近7天"+df2.format(cal.getTime()));
Calendar ca2 =Calendar.getInstance();
//最近N个月
ca2.add(Calendar.MONTH,-1);//最近一个月
System.out.println("最近一个月"+df2.format(ca2.getTime()));
Calendar ca3 =Calendar.getInstance();
//最近N个年
ca3.add(Calendar.YEAR,-1);//最近一年
System.out.println("最近一年"+df2.format(ca3.getTime()));
} catch (Exception e) {
e.printStackTrace();
}
}
}