JAVA如何实现留言时间(几秒前，几分钟前，几小时前....)的功能

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简介

最近在web前端需要实现将一个发布或创建日期转换显示为是几秒前，几分钟前…参考来自stackoverflow上的代码：

import java.util.Date;

public class TimeCountUtil {
   
   
   	private static final long ONE_MINUTE = 60000L;  
       private static final long ONE_HOUR = 3600000L;  
       private static final long ONE_DAY = 86400000L;  
       private static final long ONE_WEEK = 604800000L;  
     
       private static final String ONE_SECOND_AGO = "秒前";  
       private static final String ONE_MINUTE_AGO = "分钟前";  
       private static final String ONE_HOUR_AGO = "小时前";  
       private static final String ONE_DAY_AGO = "天前";  
       private static final String ONE_MONTH_AGO = "月前";  
       private static final String ONE_YEAR_AGO = "年前";  
     
       //main方法测试  
       /*public static void main(String[] args) throws ParseException {  
           SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); 
          
           Date date = format.parse("2019-03-18 13:25:40");  
           System.out.println(format(date));  
       }*/
       
       
       //实际调用方法
       public String timeCount(Date dateTime) {
       	String format = format(dateTime);
       	return format;
       }
       //时间转换  
       public static String format(Date date) {  
           long delta = new Date().getTime() - date.getTime();  
           if (delta < 1L * ONE_MINUTE) {  
               long seconds = toSeconds(delta);  
               return (seconds <= 0 ? 1 : seconds) + ONE_SECOND_AGO;  
           }  
           if (delta < 45L * ONE_MINUTE) {  
               long minutes = toMinutes(delta);  
               return (minutes <= 0 ? 1 : minutes) + ONE_MINUTE_AGO;  
           }  
           if (delta < 24L * ONE_HOUR) {  
               long hours = toHours(delta);  
               return (hours <= 0 ? 1 : hours) + ONE_HOUR_AGO;  
           }  
           if (delta < 48L * ONE_HOUR) {  
               return "昨天";  
           }  
           if (delta < 30L * ONE_DAY) {  
               long days = toDays(delta);  
               return (days <= 0 ? 1 : days) + ONE_DAY_AGO;  
           }  
           if (delta < 12L * 4L * ONE_WEEK) {  
               long months = toMonths(delta);  
               return (months <= 0 ? 1 : months) + ONE_MONTH_AGO;  
           } else {  
               long years = toYears(delta);  
               return (years <= 0 ? 1 : years) + ONE_YEAR_AGO;  
           }  
       }  
     
       private static long toSeconds(long date) {  
           return date / 1000L;  
       }  
     
       private static long toMinutes(long date) {  
           return toSeconds(date) / 60L;  
       }  
     
       private static long toHours(long date) {  
           return toMinutes(date) / 60L;  
       }  
     
       private static long toDays(long date) {  
           return toHours(date) / 24L;  
       }  
     
       private static long toMonths(long date) {  
           return toDays(date) / 30L;  
       }  
     
       private static long toYears(long date) {  
           return toMonths(date) / 365L;  
       }  
}

注意：
在这个类中main只是起到了测试作用，但是实际开发时需要涉及到调用问题，所以定义了timeCount（）方法用于外部调用，直接外部创建工具类TimeCountUtil 对象，然后调用timeCount（）方法即可，此方法传入的参数是Date类型，如果是String类型可以另外的进行格式转换即可。

例如：

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class Test {

   public static void main(String[] args) {
   	TimeCountUtil timeCountUtil = new TimeCountUtil();
   	
   	SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); 
       Date date = null;
   	try {
   		date = format.parse("2019-03-18 14:01:40");
   	} catch (ParseException e) {
   		// TODO Auto-generated catch block
   		e.printStackTrace();
   	}
       
   	System.out.println(timeCountUtil.timeCount(date));
   }
}