java常用日期操作

 

 

1.UTC时间转换日期字符串输出

DateTimeFormatter BING_INSTANT_PARSER = new DateTimeFormatterBuilder()
	.append(DateTimeFormatter.ISO_INSTANT).toFormatter();

String stringFromBing = "2021-09-24T21:51:00Z";
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
Instant instant = BING_INSTANT_PARSER.parse(stringFromBing, Instant::from);
ZoneId zoneId = ZoneId.systemDefault();
LocalDateTime localDateTime = LocalDateTime.ofInstant(instant, zoneId);
String dateStr = formatter.format(localDateTime);

 

2.根据开始日期 ，需要的工作日天数 ，计算工作截止日期，并返回截止日期

/** 
 * @param startDate 开始日期 
 * @param workDay 工作日天数(周一到周五) 
 * @return Date类型 
 * @createTime 2014-2-14 
 * @author Sunqinbo 
 */  
public static Date getWorkDay(Date startDate, int workDay) {  
    Calendar c1 = Calendar.getInstance();  
    c1.setTime(startDate);  
    for (int i = 0; i < workDay; i++) {  
        c1.set(Calendar.DATE, c1.get(Calendar.DATE) + 1);  
        if (Calendar.SATURDAY == c1.get(Calendar.SATURDAY) || Calendar.SUNDAY == c1.get(Calendar.SUNDAY)) {  
            workDay = workDay + 1;  
            c1.set(Calendar.DATE, c1.get(Calendar.DATE) + 1);  
            continue;  
        }  
    }  
    SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");  
    System.out.println(df.format(c1.getTime()) + " " + getWeekOfDate(c1.getTime()));  
    return c1.getTime(); 
}

  

3.将日期加上某些天或减去天数 

/** 
 * 将日期加上某些天或减去天数 
 * @param date 带处理日期 
 * @param to 加减日期 
 * @return 
 */  
public static Date dateAdd(String date, int to){  
    Date d = null;  
    try{  
        d = java.sql.Date.valueOf(date);  
    } catch (Exception e){  
        d = new Date();  
    }  
    Calendar instance = Calendar.getInstance();  
    instance.setTime(d);  
    instance.add(Calendar.DATE, to);  
    return instance.getTime();  
}