java日期的用法

public class DateTest {

	public static void main(String[] args) {
		Calendar calendar = new GregorianCalendar();
		Date trialTime = new Date();
		calendar.setTime(trialTime);
		//另一种方法
		//Class cc = Class.forName("java.util.GregorianCalendar");
		//Calendar c = (GregorianCalendar)cc.newInstance();

		// 公元前还是公元后
		System.out.println("ERA: "+calendar.get(Calendar.ERA));
		//指那一年
		System.out.println("YEAR: "+calendar.get(Calendar.YEAR));
		//那一月，但要加1
		System.out.println("MONTH: "+calendar.get(Calendar.MONTH));
		//这一年的第几周
		System.out.println("WEEK_OF_YEAR: "+calendar.get(Calendar.WEEK_OF_YEAR));
		//这一月的第几周
		System.out.println("WEEK_OF_MONTH: "+calendar.get(Calendar.WEEK_OF_MONTH));
		//这一月的多少号
		System.out.println("DATE: "+calendar.get(Calendar.DATE));
		//这一月的第几天，相当于多少号
		System.out.println("DAY_OF_MONTH: "+calendar.get(Calendar.DAY_OF_MONTH));
		//这一年的第几天
		System.out.println("DAY_OF_YEAR: "+calendar.get(Calendar.DAY_OF_YEAR));
		//这一周的多少天，星期几
		System.out.println("DAY_OF_WEEK: "+calendar.get(Calendar.DAY_OF_WEEK)); 
		
		Date d = new Date();
		SimpleDateFormat sdf = new SimpleDateFormat("HH:mm:ss yyyy-mm-dd");
		//格式化输出 
		System.out.println(sdf.format(d));
		
		//将字符串转化为Date
		//String s = "08:02:30 1850-02-01";
		//try {
		//		Date str = sdf.parse(s);
		//} catch (ParseException e) {
		//		e.printStackTrace();
		//}

	}

}