求 当前日期 的周一 和周日 日期（以周一为一周的开始）

Question

比如说
今天是4-11号 要求出 周一也就是4-05号 和周日 4-11号这段代码是求出 以周日为一周开始的代码 求 以周一开始的 不知道改哪里
int dayofweek = cal.get(cal.DAY_OF_WEEK) - cal.getFirstDayOfWeek();   
    cal.add(cal.DATE,1 - dayofweek);             
    String monday = sdf.format(cal.getTime());
    System.out.println("本周一:"+monday);     

Answer 1

楼主可以看一下这个，不知道有用吗
http://www.javaeye.com/topic/407658

Answer 2

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
Calendar c = Calendar.getInstance();
int week1 = c.get(Calendar.DAY_OF_WEEK);
c.add(Calendar.DAY_OF_MONTH,2-week1);
System.out.println("1:  "+sdf.format(c.getTime()));
c.add(Calendar.DAY_OF_MONTH,6);
System.out.println("7:  "+sdf.format(c.getTime()));

Answer 3

public class Test {    public static void main(String[] args) {
        WeekScope scope = WeekScope.getInstance(WeekStart.MONDAY);
        System.out.println(scope);
    }
}import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;public class WeekScope {    private WeekStart firstDayOfWeek;
    private Date firstDay;
    private Date lastDay;    private WeekScope(Date firstDay, Date lastDay, WeekStart firstDayOfWeek) {
        this.firstDay = firstDay;
        this.lastDay = lastDay;
        this.firstDayOfWeek = firstDayOfWeek;
    }    public static WeekScope getInstance(WeekStart firstDayOfWeek) {
        Calendar c = Calendar.getInstance();
        c.setFirstDayOfWeek(firstDayOfWeek.getValue());
        c.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
        Date firstDay = c.getTime();
        c.set(Calendar.DAY_OF_WEEK, Calendar.SUNDAY);
        Date lastDay = c.getTime();
        return new WeekScope(firstDay, lastDay, firstDayOfWeek);
    }    public Date getFirstDay() {
        return firstDay;
    }
    public Date getLastDay() {
        return lastDay;
    }    public String toString() {
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
        return "firstDayOfWeek: " + firstDayOfWeek + ", first: " + sdf.format(firstDay) + ", last: " + sdf.format(lastDay);
    }    public enum WeekStart {        SUNDAY(Calendar.SUNDAY),
        MONDAY(Calendar.MONDAY),
        TUESDAY(Calendar.TUESDAY),
        WEDNESDAY(Calendar.WEDNESDAY),
        THURSDAY(Calendar.THURSDAY),
        FRIDAY(Calendar.FRIDAY),
        SATURDAY(Calendar.SATURDAY);        private int value;        private WeekStart(int value) {
            this.value = value;
        }        public int getValue() {
            return this.value;
        }
    }
}