Java 时间类型详解
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SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
1.Calendar 转化 String
//获取当前时间的具体情况,如年,月,日,week,date,分,秒等
Calendar calendat =
Calendar.getInstance();
SimpleDateFormat
sdf = new SimpleDateFormat("yyyy-MM-dd");
String dateStr = sdf.format(calendar.getTime());
2.String 转化Calendar
String
str="2010-5-27";
SimpleDateFormat sdf= new SimpleDateFormat("yyyy-MM-dd");
Date date =sdf.parse(str);
Calendar calendar = Calendar.getInstance();
calendar.setTime(date);
3.Date 转化String
SimpleDateFormat sdf= new SimpleDateFormat("yyyy-MM-dd");
String dateStr=sdf.format(new Date());
4.String
转化Date
String str="2010-5-27";
SimpleDateFormat sdf= new SimpleDateFormat("yyyy-MM-dd");
Date birthday = sdf.parse(str);
5.Date 转化Calendar
Calendar
calendar = Calendar.getInstance();
calendar.setTime(new java.util.Date());
6.Calendar转化Date
Calendar
calendar = Calendar.getInstance();
java.util.Date date =calendar.getTime();
7.Date 转成 String
System.out.println(sdf.format(new Date()));
8.String 转成 Timestamp
Timestamp ts = Timestamp.valueOf("2011-1-14 08:11:00");
9.Timestamp 转成 String
sdf.format(ts);
Timestamp和Date多数用法是一样的。
10.Date 转 TimeStamp
SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String time = df.format(new Date());
Timestamp ts = Timestamp.valueOf(time);
11.日期比较大小
String
ti="2010-11-25 20:11:00";
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd
HH:mm:ss");
Date time=sdf.parse(ti);
String
ti2="2011-11-26 20:11:00";
Date time2=sdf.parse(ti2);
int
c=ti2.compareTo(ti);
if(c>0){
System.out.println(ti+"大");
}else if(c==0){
System.out.println("一样大");
}else{
System.out.println(ti2+"大");
}
12.Date/ Timestamp 转成 Calendar
Calendar
calendar = Calendar.getInstance();
calendar.setTime(startDate);
calendar.add(Calendar.YEAR,
2); //日期加2年
System.out.println(calendar.getTime());
calendar.add(Calendar.DATE, -30); //日期加30天
System.out.println(calendar.getTime());
calendar.add(Calendar.MONTH, 3); //日期加3个月
System.out.println(calendar.getTime());
DateUtil
/**
* 时间格式的转换(Timestamp转换为string)
* @author zcm
* @param time
* @return String类型的时间格式字符串
*/
public static String convert(Timestamp time) {
SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String result = df.format((Date) time);
return result;
}
/**
* 获取当时系统时间（timestamp）
* @author zcm
* @return Timestamp类型的时间格式
*/
public static Timestamp getNow() {
Date date = new Date();
SimpleDateFormat simDate = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
Timestamp now=Timestamp.valueOf(simDate.format(date));
return now;
}
/**
* 将date转换为string类型yyyy-MM-dd
* @param date
* @return
*@author Jimmy
*/
public static String dateConvertToString(Date date){
SimpleDateFormat formatter = new SimpleDateFormat( "yyyy-MM-dd ");
String time = formatter.format(date);//格式化数据
return time;
}
/**
* 获取当前时间的毫秒数
* @return
*@author Jimmy
*/
public static Long getTime(){
Date dt= new Date();
Long time= dt.getTime();
return time;
}
/**
* 将字符串类型转换为calendar
* @return
*@author Jimmy
* @throws ParseException
*/
public static Calendar convertToCalendar(String date) throws ParseException{
Date d = new SimpleDateFormat("yyyy-MM-dd").parse(date);
Calendar cal=Calendar.getInstance();
cal.setTime(d);
return cal;
}
public static void main(String[] args) throws ParseException {
Calendar now = Calendar.getInstance();
System.out.println("年: " + now.get(Calendar.YEAR));
System.out.println("月: " + (now.get(Calendar.MONTH) + 1) + "");
System.out.println("日: " + now.get(Calendar.DAY_OF_MONTH));
System.out.println("时: " + now.get(Calendar.HOUR_OF_DAY));
System.out.println("分: " + now.get(Calendar.MINUTE));
System.out.println("秒: " + now.get(Calendar.SECOND));
System.out.println("当前时间毫秒数：" + now.getTimeInMillis());
System.out.println("当前月的天数：" + now.getActualMaximum(Calendar.DATE));
System.out.println(now.getTime());
//给定日期查看最大数
now.set(Calendar.YEAR,2002);
now.set(Calendar.MONTH,6);//7月
int maxDate = now.getActualMaximum(Calendar.DATE);
Date d = new Date();
System.out.println(d);
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String dateNowStr = sdf.format(d);
System.out.println("格式化后的日期：" + dateNowStr);
String str = "2012-1-13 17:26:33"; //要跟上面sdf定义的格式一样
Date today = sdf.parse(str);
System.out.println("字符串转成日期：" + today);
}
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