java根据年获取星期和日期 java获取年的周数

import java.text.SimpleDateFormat; import java.util.Calendar; import java.util.Date; import java.util.GregorianCalendar;     public class Test {       // 获取当前时间所在年的周数     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);     }       // 获取当前时间所在年的最大周数     public static int getMaxWeekNumOfYear(int year) {         Calendar c = new GregorianCalendar();         c.set(year, Calendar.DECEMBER, 31, 23, 59, 59);           return getWeekOfYear(c.getTime());     }       // 获取某年的第几周的开始日期     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());     }       // 获取某年的第几周的结束日期     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());     }       // 获取当前时间所在周的开始日期     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();     }       // 获取当前时间所在周的结束日期     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 = 2015;         int week = 27;           SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");         Date today = new Date();         Calendar c = new GregorianCalendar();         c.setTime(today);           System.out.println("当前时间:current date = " + sdf.format(today));         System.out.println("当前第几周:getWeekOfYear = " + getWeekOfYear(today));         System.out.println("年度总周数:getMaxWeekNumOfYear = " + getMaxWeekNumOfYear(year));         System.out.println("本周第一天:getFirstDayOfWeek = " + sdf.format(getFirstDayOfWeek(year, week)));         System.out.println("本周最后一天:getLastDayOfWeek = " + sdf.format(getLastDayOfWeek(year, week)));         System.out.println("本周第一天:getFirstDayOfWeek = " + sdf.format(getFirstDayOfWeek(today)));         System.out.println("本周最后一天:getLastDayOfWeek = " + sdf.format(getLastDayOfWeek(today)));     } }                      //输出结果: //        当前时间:current date = 2015-07-07 16:35:07 //        当前第几周:getWeekOfYear = 27 //        年度总周数:getMaxWeekNumOfYear = 52 //        getFirstDayOfWeek = 2015-07-06 16:35:07 //        getLastDayOfWeek = 2015-07-12 16:35:07 //        getFirstDayOfWeek = 2015-07-06 16:35:07 //        getLastDayOfWeek = 2015-07-12 16:35:07