时间戳与字符串相互转换

/** 
     * 时间戳转换成日期格式字符串 
     * @param seconds 精确到秒的字符串 
     * @param formatStr 
     * @return 
     */  
    public static String timeStamp2Date(String seconds,String format) {  
        if(seconds == null || seconds.isEmpty() || seconds.equals("null")){  
            return "";  
        }  
        if(format == null || format.isEmpty()) format = "yyyy-MM-dd HH:mm:ss";  
        SimpleDateFormat sdf = new SimpleDateFormat(format);  
        return sdf.format(new Date(Long.valueOf(seconds+"000")));  
    }  
    /** 
     * 日期格式字符串转换成时间戳 
     * @param date 字符串日期 
     * @param format 如：yyyy-MM-dd HH:mm:ss 
     * @return 
     */  
    public static String date2TimeStamp(String date_str,String format){  
        try {  
            SimpleDateFormat sdf = new SimpleDateFormat(format);  
            return String.valueOf(sdf.parse(date_str).getTime()/1000);  
        } catch (Exception e) {  
            e.printStackTrace();  
        }  
        return "";  
    }  
      
    /** 
     * 取得当前时间戳（精确到秒） 
     * @return 
     */  
    public static String timeStamp(){  
        long time = System.currentTimeMillis();  
        String t = String.valueOf(time/1000);  
        return t;  
    }  
      
    //  输出结果：  
    //  timeStamp=1417792627  
    //  date=2014-12-05 23:17:07  
    //  1417792627  
    public static void main(String[] args) {  
        String timeStamp = timeStamp();  
        System.out.println("timeStamp="+timeStamp);  
          
        String date = timeStamp2Date(timeStamp,"yyyy-MM-dd HH:mm:ss");  
        System.out.println("date="+date);  
          
        String timeStamp2 = date2TimeStamp(date,"yyyy-MM-dd HH:mm:ss");  
        System.out.println(timeStamp2);  
    }