获取周一的日期

/**
     * 取得当前时间字符串
     */
    private String getNowTime() {
        return AppDateUtils.toString(new Date(), AppDateUtils.yyyyMMdd);
    }

    /**
     * 取得时间对应的周几
     */
    private int getWeek(String dateStr) {
        Date date = AppDateUtils.toDate(dateStr, AppDateUtils.yyyyMMdd);
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        return calendar.get(Calendar.DAY_OF_WEEK);
    }

    /**
     * 获取当前的周一时间字符串
     *
     * @return
     */
    private String getNowWeekTime() {
        return AppDateUtils.toString(getMondayDate(), AppDateUtils.yyyyMMdd);
    }

    /**
     * 获取上周时间的字符串
     */
    private String getLastWeekTime() {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(getMondayDate());
        calendar.add(Calendar.DAY_OF_MONTH, -7);
        Date date = calendar.getTime();
        return AppDateUtils.toString(date, AppDateUtils.yyyyMMdd);
    }

    /**
     * 获取周一的日期
     */
    private Date getMondayDate() {
        Date date = new Date();
        Calendar calendar = new GregorianCalendar();
        int curDay = calendar.get(Calendar.DAY_OF_WEEK);
        calendar.setTime(date);
        if (curDay == 1) {
            calendar.add(GregorianCalendar.DATE, -6);
        } else {
            calendar.add(GregorianCalendar.DATE, 2 - curDay);
        }
        return calendar.getTime();
    }