Android之计算两个时间的相差

参数：   sdate = 2013-07-16 16:14:47

/**
     * 以友好的方式显示时间
     * @param sdate
     * @return
     */
    public static String friendly_time(String sdate) {
        Date time = toDate(sdate);
        if(time == null) {
            return "Unknown";
        }
        String ftime = "";
        Calendar cal = Calendar.getInstance();
        
        //判断是否是同一天
        String curDate = dateFormater2.get().format(cal.getTime());
        String paramDate = dateFormater2.get().format(time);
        if(curDate.equals(paramDate)){
            int hour = (int)((cal.getTimeInMillis() - time.getTime())/3600000);
            if(hour == 0)
                ftime = Math.max((cal.getTimeInMillis() - time.getTime()) / 60000,1)+"分钟前";
            else 
                ftime = hour+"小时前";
            return ftime;
        }
        
        long lt = time.getTime()/86400000;
        long ct = cal.getTimeInMillis()/86400000;
        int days = (int)(ct - lt);        
        if(days == 0){
            int hour = (int)((cal.getTimeInMillis() - time.getTime())/3600000);
            if(hour == 0)
                ftime = Math.max((cal.getTimeInMillis() - time.getTime()) / 60000,1)+"分钟前";
            else 
                ftime = hour+"小时前";
        }
        else if(days == 1){
            ftime = "昨天";
        }
        else if(days == 2){
            ftime = "前天";
        }
        else if(days > 2 && days <= 10){ 
            ftime = days+"天前";            
        }
        else if(days > 10){            
            ftime = dateFormater2.get().format(time);
        }
        return ftime;
    }

/**
     * 将字符串转位日期类型
     * @param sdate
     * @return
     */
    public static Date toDate(String sdate) {
        try {
            return dateFormater.get().parse(sdate);
        } catch (ParseException e) {
            return null;
        }
    }

private final static ThreadLocal<SimpleDateFormat> dateFormater = new ThreadLocal<SimpleDateFormat>() {
        @Override
        protected SimpleDateFormat initialValue() {
            return new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        }
    };

private final static ThreadLocal<SimpleDateFormat> dateFormater2 = new ThreadLocal<SimpleDateFormat>() {
        @Override
        protected SimpleDateFormat initialValue() {
            return new SimpleDateFormat("yyyy-MM-dd");
        }
    };

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