对于星期操作的公用函数

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;

/**
* 该类定义了一些对于星期操作的公用函数
*
* @author administrator
* @version 1.0
*/
public class WeekUtil {
/**
* 取得当前日期是多少周
*
* @param date
* @return
*/
public static int getWeekOfYear(Date date) {
Calendar c = new GregorianCalendar();
c.setFirstDayOfWeek(Calendar.MONDAY);
c.setMinimalDaysInFirstWeek(7);
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 = new GregorianCalendar();
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 = new GregorianCalendar();
c.set(Calendar.YEAR, year);
c.set(Calendar.MONTH, Calendar.JANUARY);
c.set(Calendar.DATE, 1);
       
Calendar cal = (GregorianCalendar) c.clone();
cal.add(Calendar.DATE, week * 7);

return getFirstDayOfWeek(cal.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 = new GregorianCalendar();
c.set(Calendar.YEAR, year);
c.set(Calendar.MONTH, Calendar.JANUARY);
c.set(Calendar.DATE, 1);

Calendar cal = (GregorianCalendar) c.clone();
cal.add(Calendar.DATE, week * 7);

return getLastDayOfWeek(cal.getTime());
}

/**
* 取得当前日期所在周的第一天
*
* @param date
* @return
*/
public static Date getFirstDayOfWeek(Date date) {
Calendar c = new GregorianCalendar();
c.setFirstDayOfWeek(Calendar.MONDAY);
c.setTime(date);
c.set(Calendar.DAY_OF_WEEK, c.getFirstDayOfWeek()); // Monday
return c.getTime();
}

/**
* 取得当前日期所在周的最后一天
*
* @param date
* @return
*/
public static Date getLastDayOfWeek(Date date) {
Calendar c = new GregorianCalendar();
c.setFirstDayOfWeek(Calendar.MONDAY);
c.setTime(date);
c.set(Calendar.DAY_OF_WEEK, c.getFirstDayOfWeek() + 6); // Sunday
return c.getTime();
}

public static void main(String[] args) {
int year = 2010;
int week = 7;

Calendar c = new GregorianCalendar();
c.set(2010, Calendar.MARCH, 23);
Date d = c.getTime();
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
System.out.println("current date = " + sdf.format(d));
System.out.println("getWeekOfYear = " + getWeekOfYear(d));
System.out.println("getMaxWeekNumOfYear = " + getMaxWeekNumOfYear(year));
System.out.println("getFirstDayOfWeek = " + sdf.format((getFirstDayOfWeek(year, week))));
System.out.println("getLastDayOfWeek = " + sdf.format(getLastDayOfWeek(year, week)));
System.out.println("getFirstDayOfWeek = " + sdf.format(getFirstDayOfWeek(d)));
System.out.println("getLastDayOfWeek = " + sdf.format(getLastDayOfWeek(d)));

}