时间工具类（封装）

import java.text.DateFormat;
import java.text.DecimalFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.Random;

/**
* 时间的工具类
*/
public class DateUtil {

private final static SimpleDateFormat SDF_YEAR = new SimpleDateFormat("yyyy");

private final static SimpleDateFormat SDF_DAY = new SimpleDateFormat("yyyy-MM-dd");

private final static SimpleDateFormat SDF_DAYS = new SimpleDateFormat("yyyyMMdd");

private final static SimpleDateFormat SDF_TIMES = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

private final static SimpleDateFormat SDF_TIME = new SimpleDateFormat("yyyy-MM-dd HH:mm");

private final static SimpleDateFormat SDF_MONTH = new SimpleDateFormat("yyyy-MM");

private final static SimpleDateFormat SN_TIMES = new SimpleDateFormat("yyyyMMddHHmmss");

/**
* 精确到毫秒的完整时间    如：yyyy-MM-dd HH:mm:ss.S
*/
public static final String FORMAT_FULL = "yyyy-MM-dd HH:mm:ss.S";

//这是sn生成的方法 具体到秒 加二位随机数
public static Long createSn() {
int i = new Random().nextInt(10000);
DecimalFormat localDecimalFormat = new DecimalFormat("0000");
return Long.parseLong(getSn() + "" + localDecimalFormat.format(i));
}

//2017 06 02 18 26 50> yyyy-MM-dd HH:mm:ss
public static String setStandardDate(String sn) {
StringBuilder date = new StringBuilder(sn);
date.insert(4, "-");
date.insert(7, "-");
date.insert(10, " ");
date.insert(13, ":");
date.insert(16, ":");
return date.toString();
}

/**
* 获取YYYY格式
*
* @return
*/
public static String getYear() {
return SDF_YEAR.format(new Date());
}

/**
* 获取YYYY-MM-DD格式
*
* @return
*/
public static String getDay() {
return SDF_DAY.format(new Date());
}

/**
* 获取YYYYMMDD格式
*
* @return
*/
public static String getDays() {
return SDF_DAYS.format(new Date());
}

/**
* 获取YYYY-MM-DD hh:mm:ss格式
*
* @return
*/
public static String getTimes() {
return SDF_TIMES.format(new Date());
}

/**
* 获取YYYY-MM-DD hh:mm:ss格式
*
* @return
*/
public static String getSn() {
return SN_TIMES.format(new Date());
}

/**
* 获取YYYY-MM-DD hh:mm格式
*
* @return
*/
public static String getTime() {
return SDF_TIME.format(new Date());
}

/**
* @param s
* @param e
* @return boolean
* @throws
* @Title: compareDate
* @Description: 日期比较，如果s>=e 返回true 否则返回false
* @author luguosui
*/
public static boolean compareDate(String s, String e) {
if (fomatDate(s) == null || fomatDate(e) == null) {
return false;
}
return fomatDate(s).getTime() >= fomatDate(e).getTime();
}

/**
* 格式化日期
*
* @return
*/
public static Date fomatDate(String date) {
DateFormat fmt = new SimpleDateFormat("yyyy-MM-dd");
try {
return fmt.parse(date);
} catch (ParseException e) {
e.printStackTrace();
return null;
}
}

/**
* 格式化日期
*
* @return
*/
public static Date fomatTime(String date) {
DateFormat fmt = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
try {
return fmt.parse(date);
} catch (ParseException e) {
e.printStackTrace();
return null;
}
}

/**
* 校验日期是否合法
*
* @return
*/
public static boolean isValidDate(String s) {
DateFormat fmt = new SimpleDateFormat("yyyy-MM-dd");
try {
fmt.parse(s);
return true;
} catch (Exception e) {
// 如果throw java.text.ParseException或者NullPointerException，就说明格式不对
return false;
}
}

// 将时间戳转为字符串
public static String getStrTime(String cc_time) {
String re_StrTime = null;
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm");
long lcc_time = Long.valueOf(cc_time);
re_StrTime = sdf.format(new Date(lcc_time));
return re_StrTime;
}

// 将字符串转为时间戳
public static String getTime(String user_time) {
String re_time = null;
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm");
Date d;
try {
d = sdf.parse(user_time);
long l = d.getTime();
String str = String.valueOf(l);
re_time = str.substring(0, 10);
} catch (ParseException e) {
e.printStackTrace();
}
return re_time;
}

// 将字符串转为时间戳
public static String getDate(String user_time) {
String re_time = null;
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
Date d;
try {
d = sdf.parse(user_time);
long l = d.getTime();
String str = String.valueOf(l);
re_time = str.substring(0, 10);
} catch (ParseException e) {
e.printStackTrace();
}
return re_time;
}

/**
* 获取时间戳
*
* @return 获取时间戳
*/
public static String getTimeString() {
SimpleDateFormat df = new SimpleDateFormat(FORMAT_FULL);
Calendar calendar = Calendar.getInstance();
return df.format(calendar.getTime());
}

public static int getDiffYear(String startTime, String endTime) {
DateFormat fmt = new SimpleDateFormat("yyyy-MM-dd");
try {
long aa = 0;
int years = (int) (((fmt.parse(endTime).getTime() - fmt.parse(
startTime).getTime()) / (1000 * 60 * 60 * 24)) / 365);
return years;
} catch (Exception e) {
// 如果throw java.text.ParseException或者NullPointerException，就说明格式不对
return 0;
}
}

/**
* <li>功能描述：时间相减得到天数

c668
*
* @param beginDateStr
* @param endDateStr
* @return long
* @author Administrator
*/
public static long getDaySub(String beginDateStr, String endDateStr) {
long day = 0;
java.text.SimpleDateFormat format = new java.text.SimpleDateFormat("yyyy-MM-dd");
java.util.Date beginDate = null;
java.util.Date endDate = null;

try {
beginDate = format.parse(beginDateStr);
endDate = format.parse(endDateStr);
} catch (ParseException e) {
e.printStackTrace();
}
day = (endDate.getTime() - beginDate.getTime()) / (24 * 60 * 60 * 1000);

return day;
}

/**
* 得到n天之后的日期
*
* @param days
* @return
*/
public static String getAfterDayDate(String days) {
int daysInt = Integer.parseInt(days);

// java.util包
Calendar canlendar = Calendar.getInstance();
// 日期减 如果不够减会将月变动
canlendar.add(Calendar.DATE, daysInt);
Date date = canlendar.getTime();

//        SimpleDateFormat sdfd = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
SimpleDateFormat sdfd = new SimpleDateFormat("yyyy-MM-dd");
String dateStr = sdfd.format(date);

return dateStr;
}

/**
* 得到n天之后是周几
*
* @param days
* @return
*/
public static String getAfterDayWeek(String days) {
int daysInt = Integer.parseInt(days);
// java.util包
Calendar canlendar = Calendar.getInstance();
// 日期减 如果不够减会将月变动
canlendar.add(Calendar.DATE, daysInt);
Date date = canlendar.getTime();

SimpleDateFormat sdf = new SimpleDateFormat("E");
String dateStr = sdf.format(date);

return dateStr;
}

/**
* 获取每月的天数
*
* @param month
*/
public static int getMonthDays(String month) {

// String month = "2015-05";
try {
Date date = SDF_MONTH.parse(month);
// java.util包
Calendar calendar = new GregorianCalendar();
calendar.setTime(date);
return calendar.getActualMaximum(Calendar.DAY_OF_MONTH);
} catch (ParseException e) {
e.printStackTrace();
}
//默认返回最大值每月的最大值31
return 31;
}

/**
* 入口测试方法
*
* @param args
*/
public static void main(String[] args) {

int days = getMonthDays("2015-02");
System.out.println(days);
System.out.println(DateUtil.SDF_TIME);
}
}