java日期

1.

Date now1=new Date();
System.out.println(df.format(now1));//當前時間          System.out.println(df.format(now1.getTime()+60*1000*10));//十分鐘後的時間

2.

/**
     * 返回last1與now1相差的秒數
     * @param(string) last1,now1
     * if(last1==null)last1=new Date()
     * if(now1==null)now1=new Date()
     * @param apartSeconds
     * @return
     * @throws ParseException 
     */
    public long apartSeconds(String last1,String now1) throws ParseException{       
        DateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        Date now=null;
        Date last=null;
        if(now1==null){
            now=new Date();
        }else{
            now=df.parse(now1);
        }
        if(last1==null){
            last=new Date();
        }else{
            last=df.parse(last1);
        }       
        return (now.getTime()-last.getTime())/1000;
    }

3.

public String getThisWeekMonday(String time,int k) throws ParseException{
                    //time='2015-03-02'  傳輸進的日期
                    //k==1  return本週週一
                    //k==2  return本週週日
                    //k==3  return返回本月的天數
                    String monday="";
                    SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");
                    Date date=sdf.parse(time);
                    Calendar cal=Calendar.getInstance();
                    cal.setTime(date);
                    if(k==1){
                        cal.add(Calendar.DAY_OF_MONTH, -1);
                        cal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
                        monday=sdf.format(cal.getTime());
                    }else if(k==2){
                        cal.set(Calendar.DAY_OF_WEEK, Calendar.SUNDAY);
                        cal.add(Calendar.WEEK_OF_YEAR, 1);
                        monday=sdf.format(cal.getTime());
                    }else if(k==3){
                        monday=cal.getActualMaximum(Calendar.DAY_OF_MONTH)+"";
                    }
                    //System.out.println(monday);
                    return monday;
                }