TimeUtil --- 时间格式化工具

/**
 * 时间格式化工具
 */

public class TimeUtil {

    private static TimeUtil instance;

    private SimpleDateFormat sf;

    public TimeUtil(){
        sf = new SimpleDateFormat();
    }

    public static TimeUtil getInstance(){
        if (null==instance){
            instance = new TimeUtil();
        }
        return instance;
    }

    public String fotmatTime(long time){
        long startOfToday = getTimeStartOfToday();
        //检测是否是今天以内
        sf.applyPattern("HH:mm");
        long t = time - startOfToday;
        if (t>=0 && t<86400000){
            return sf.format(new Date(time));
        }
        //检测是否是昨天开始
        else if(-t >= 0 && -t<86400000){
            return "昨天"+sf.format(new Date(time));
        }
        //检测是否是今天开始
        else if(-t>=86400000 && -t<172300000){
            return "前天"+sf.format(new Date(time));
        }
        //3天前
        return "3天前";
    }

    /**
     * 获取今天的起始时间
     * @return
     */
    private long getTimeStartOfToday(){
        Calendar c = Calendar.getInstance();
        c.set(Calendar.HOUR_OF_DAY,0);
        c.set(Calendar.MINUTE,0);
        c.set(Calendar.SECOND,0);
        c.set(Calendar.MILLISECOND,0);
        return c.getTimeInMillis();
    }
}