Java 时间工具类

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());

13.将毫秒数转为String

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
Timestamp scurrtest = new Timestamp(millis);
String time=sdf.format(scurrtest);

public static String
convert(Timestamp time) {

SimpleDateFormat df = new
SimpleDateFormat("yyyy-MM-dd
HH:mm:ss");

String result =
df.format((Date) time);

return
result;

}

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;

}

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;

}

　　　　//根据传入的日期计算距今多少天

　　　　public static Integer getValidDays(Date date){
　　　　　　　　int days=0;
　　　　　　　　Date now=new Date();
　　　　　　　　int i = now.compareTo(date);
　　　　　　　　if (i>0) {
　　　　　　　　　　return 0;
　　　　　　　　}else{
　　　　　　　　　　days = (int) Math.abs((now.getTime() - date.getTime())
　　　　　　　　　　/ (24 * 60 * 60 * 1000));
　　　　　　　　}

　　　　　　　return days;
　　　　　}

public static
Long  getTime(){

Date dt= new
Date();

Long time= dt.getTime();

return time;

}

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);

}

/**
 * 计算两个日期之间的天数
 */
public class DateUtils {
   public static Integer daysBetween(Date smdate, Date bdate){
      try{
         SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");
         smdate=sdf.parse(sdf.format(smdate));
         bdate=sdf.parse(sdf.format(bdate));
         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));
      }catch (Exception e){
         throw new RuntimeException("The Date sub error");
      }
   }

/**
 * 自然年加法
 * @param date
 * @return
 */
public static Date getAddDate(Date date,Integer year){
   try{
      Calendar calendar = Calendar.getInstance();
      calendar.setTime(date);
      calendar.add(Calendar.YEAR, year);
      date = calendar.getTime();
      SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
      String dateStr = simpleDateFormat.format(date);
      Date parse = simpleDateFormat.parse(dateStr);
      return parse;
   }catch (Exception e){
      throw new RuntimeException("The Date add error");
   }
}

　　　　/**

     *

     * @param 要转换的毫秒数

     * @return 该毫秒数转换为 * days * hours * minutes * seconds 后的格式

     * @author fy.zhang

     */

    public static String formatDuring(long mss) {

        long days = mss / (1000 * 60 * 60 * 24);

        long hours = (mss % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60);

        long minutes = (mss % (1000 * 60 * 60)) / (1000 * 60);

        long seconds = (mss % (1000 * 60)) / 1000;

        return days + " days " + hours + " hours " + minutes + " minutes "

                + seconds + " seconds ";

    }