java得到某年某周的第一天实现思路及代码

直接上代码

import java.util.calendar;
import java.util.date;
import org.apache.commons.logging.log;
import org.apache.commons.logging.logfactory;
/**
* 日期工具类
* @author wxq
*
*/
public class dateutils {

private static final log log = logfactory.getlog(dateutils.class);
/**
* 取得当前日期是多少周
*
* @param date
* @return
*/
public static int getweekofyear(date date) {
calendar c = calendar.getinstance();
c.setfirstdayofweek(calendar.monday);
/**设置一年中第一个星期所需的最少天数，例如，如果定义第一个星期包含一年第一个月的第一天，则使用值 1 调用此方法。
* 如果最少天数必须是一整个星期，则使用值 7 调用此方法。 **/
c.setminimaldaysinfirstweek(1);
c.settime(date);
return c.get(calendar.week_of_year);
}
/**
* 得到某一年周的总数
*
* @param year
* @return
*/
public static int getmaxweeknumofyear(int year) {
calendar c = calendar.getinstance();
c.set(year, calendar.december, 31, 23, 59, 59);
return getweekofyear(c.gettime());
}
/**
* 得到某年某周的第一天
*
* @param year
* @param week
* @return
*/
public static date getfirstdayofweek(int year, int week) {
calendar c = calendar.getinstance();
c.set(calendar.year, year);
c.set(calendar.week_of_year, week);
c.set(calendar.day_of_week, calendar.monday);//设置周一
c.setfirstdayofweek(calendar.monday);
return c.gettime();
}

/**
* 得到某年某周的最后一天
*
* @param year
* @param week
* @return
*/
public static date getlastdayofweek(int year, int week) {
calendar c = calendar.getinstance();
c.set(calendar.year, year);
c.set(calendar.week_of_year, week);
c.setfirstdayofweek(calendar.monday);
c.set(calendar.day_of_week, c.getfirstdayofweek() + 6); // sunday

return c.gettime();
}

/**
* 得到某年某月的第一天
*
* @param year
* @param month
* @return
*/
public static date getfirstdayofmonth(int year, int month) {
calendar c = calendar.getinstance();
c.set(calendar.year, year);
c.set(calendar.month, month-1);
c.set(calendar.day_of_month, c.getactualminimum(calendar.day_of_month));
return c.gettime();
}

/**
* 得到某年某月的最后一天
*
* @param year
* @param month
* @return
*/
public static date getlastdayofmonth(int year, int month) {
calendar c = calendar.getinstance();
c.set(calendar.year, year);
c.set(calendar.month, month-1);
c.set(calendar.day_of_month, c.getactualmaximum(calendar.day_of_month));
return c.gettime();
}
/**
* 得到某年某季度第一天
*
* @param year
* @param quarter
* @return
*/
public static date getfirstdayofquarter(int year, int quarter) {
int month = 0;
if (quarter > 4) {
return null;
} else {
month = (quarter - 1) * 3 + 1;
}
return getfirstdayofmonth(year, month);
}
/**
* 得到某年某季度最后一天
*
* @param year
* @param quarter
* @return
*/
public static date getlastdayofquarter(int year, int quarter) {
int month = 0;
if (quarter > 4) {
return null;
} else {
month = quarter * 3;
}
return getlastdayofmonth(year, month);
}
/**
* 得到某年第一天
*
* @param year
* @return
*/
public static date getfirstdayofyear(int year) {
return getfirstdayofquarter(year,1);
}

/**
* 得到某年最后一天
*
* @param year
* @return
*/
public static date getlastdayofyear(int year) {
return getlastdayofquarter(year,4);
}

public static void main(string[] args) {
log.info(getfirstdayofweek(2013,1));
log.info(getlastdayofweek(2013,1));

log.info(getfirstdayofmonth(2013,2));
log.info(getlastdayofmonth(2013,2));

log.info(getfirstdayofquarter(2013,2));
log.info(getlastdayofquarter(2013,2));

log.info(getfirstdayofyear(2013));
log.info(getlastdayofyear(2013));

}
}