JAVA读取系统时间的几种方法

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
/**
* 读取当前系统时间
*/
public class ReadSystemTime {

public static void main(String[] args) {
getTime_1();
getTime_2();
getTime_3();
}

/**
* 方法1
*/
public static void getTime_1(){
//此处字符串的格式可以修改
SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
Date currentTime = new Date();//得到当前系统时间
String timeStr = formatter.format(currentTime); //将日期时间格式化
System.out.println("[1] " timeStr);
//输出：[1] 2009-08-18 20:06:13
}
/**
* 方法2
*/
public static void getTime_2(){
SimpleDateFormat formatter = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
System.out.println("[2] " formatter.format(System.currentTimeMillis()));
//输出：[2] 2009/08/18 20:18:48
}
/**
* 方法3
*/
public static void getTime_3(){
Calendar todaysDate = new GregorianCalendar();
int year = todaysDate.get(Calendar.YEAR);
int month = todaysDate.get(Calendar.MONTH) 1;
int day = todaysDate.get(Calendar.DAY_OF_MONTH);
int hourOfDay = todaysDate.get(Calendar.HOUR_OF_DAY);//24小时制
//int hour = todaysDate.get(Calendar.HOUR); //12小时制
int minute = todaysDate.get(Calendar.MINUTE);
int second = todaysDate.get(Calendar.SECOND);
System.out.println("[3] " year "." month "." day
" " hourOfDay ":" minute ":" second);
//输出:[3] 2009.8.18 20:23:51
}
}