2.得到当前日期
Date date=new Date();//通过日期转换成字符串输出DateFormat format=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");String time=format.format(date);//通过字符串得到日期SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");Date date = sdf.parse("2008-08-08 12:10:12")//得到与当前日期相差几天的日期
public static Date getNextDay(Date date,int a) {Calendar calendar = Calendar.getInstance();calendar.setTime(date);calendar.add(Calendar.DAY_OF_MONTH,a);date = calendar.getTime();return date;}
3.设置定时器
import java.util.Calendar;
import java.util.Date;
import java.util.Timer;
import java.util.TimerTask;
//这个方法貌似不太正确
public class TestTimer {static int count = 0;public static void showTimer() {TimerTask task = new TimerTask() {@Overridepublic void run() {++count;System.out.println("时间=" + new Date() + " 执行了" + count + "次"); // 1次}};//设置执行时间Calendar calendar = Calendar.getInstance();int year = calendar.get(Calendar.YEAR);int month = calendar.get(Calendar.MONTH);int day = calendar.get(Calendar.DAY_OF_MONTH);//每天//定制每天的21:09:00执行，calendar.set(year, month, day, 21, 9, 00);Date date = calendar.getTime();Timer timer = new Timer();System.out.println(date);int period = 2 * 1000;//每天的date时刻执行task，每隔2秒重复执行timer.schedule(task, date, period);//每天的date时刻执行task, 仅执行一次//timer.schedule(task, date);}public static void main(String[] args) {showTimer();}
}
//这一种比较可以
public static void main(String[] args) {myTest a=new myTest();Timer timer=new Timer();timer.schedule(a,new Date());//这里的date可以自定义
}public static class myTest extends TimerTask {@Overridepublic void run() {for (int i = 0; i < 10; i++) {System.out.println("你好啊...");}}}
4.java得到本机ip
InetAddress ia=null;try {ia=ia.getLocalHost();String localname=ia.getHostName();String localip=ia.getHostAddress();System.out.println("本机名称是："+ localname);System.out.println("本机的ip是 ："+localip);} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}
5.得到前一天的日期//两个日期相差多少天public static int getBetweenDays(String date1,String date2) throws ParseException {SimpleDateFormat sdf=new SimpleDateFormat("yyyyMMdd"); Date smdate=sdf.parse(date1); Date bdate=sdf.parse(date2); Calendar cal = Calendar.getInstance(); cal.setTime(smdate); long time1 = cal.getTimeInMillis(); cal.setTime(bdate); long time2 = cal.getTimeInMillis(); long between_days=(time2-time1)/(1000*3600*24); return Integer.parseInt(String.valueOf(between_days)); }//得到日期，输入日期类型,得到当天日期的字符型public static String getTodayDatestr(String type){Date date=new Date();//通过日期转换成字符串输出DateFormat format=new SimpleDateFormat(type);String time=format.format(date);return time;}//通过字符串得到日期public static Date getDateBystr(String datestr,String type){SimpleDateFormat sdf = new SimpleDateFormat(type);Date date=null;try {date = sdf.parse(datestr);} catch (ParseException e) {// TODO Auto-generated catch blocke.printStackTrace();}return date;}//得到当前或之前或之后的日期 字符型public static String getBeforeOrAfterDate(String type,int AddorCut){Calendar cal = Calendar.getInstance();cal.add(Calendar.DATE, AddorCut);String date = new SimpleDateFormat(type).format(cal.getTime());return date;}