How does java count the current number of online users
This article mainly introduces how to count the current online number of java, has a certain reference value, interested friends can refer to, I hope you can learn a lot after reading this article, the following let the editor take you to understand.
Java counts the current number of online users
Package com.hnedu.stat
/ * *
* calculate the number of people online, indicating:
*
* put in the visit page:
* com.hnedu.stat.OnlineCounter.addUser (object object)
* ip is generally used as the input value of object. Of course, if the website counts the number of people who log in online, you can also use a user name.
* to input values as object.
*
* call to display the number of people online
* com.hnedu.stat.OnlineCounter.getOnlineCount () *
*
* com.hnedu.stat.OnlineCounter.getOnline ()
* return a List that stores the passed object value and the last time the page was visited in the form of String [].
* by crazyren 2003-08-05 eMail: hotmail.com "> c_crazyren@hotmail.com
, /
Import Java.util.List
Import java.util.ArrayList
Import javax.servlet.http.HttpSession
Public class OnlineCounter {
Private static List list = new ArrayList ()
Private OnlineCounter () {
}
Public static void addUser (Object object) {
/ / get the user's current access time
String nowtime = com.hnedu.util.StringUtils.getTime ("mm:ss")
/ / the Str array is used to store users'ip and access time.
String [] str = new String [2]
Str [0] = object.toString ()
Str [1] = nowtime
/ / the temp array is used to temporarily store the user ip and access time extracted from the list.
String [] temp = new String [2]
/ / cyclic list
For (int I = 0; I
< list.size(); i++) { temp = (String[])list.get(i); //如果从list里面取出的用户ip和str里面存放的ip相同，则更新访问时间 if(temp[0].equals(str[0])) { list.set(i,str); return; } //如果用户超过5分钟没有访问，则认为不在线 if(subTime(nowtime,temp[1]) >300) {
List.remove (I)
}
}
/ / add a new online user
List.add (str)
/ / release resources
Str = null;temp = null
}
Public static int getOnlineCount () {
/ / return the current number of online users
Return list.size ()
}
Public static List getOnline () {
Return list
}
/ * * calculate two time differences and return the difference in seconds * /
Private static int subTime (String src,String des) {
Int n = 0
Java.util.Calendar ca = java.util.Calendar.getInstance ()
Long time1 =
Com.hnedu.util.StringUtils.compareStringTime (src,des, "mm:ss")
Ca.setTimeInMillis (time1)
N = (ca.get (java.util.Calendar.MINUTE)) * 60
N = n + ca.get (java.util.Calendar.SECOND)
Return n
}
}
The two methods in the referenced StringUtils:
/ * *
* get the current time
Time format of * @ param parrten output
* @ return return time
, /
Public static String getTime (String parrten)
{
String timestr
If (parrten==null | | parrten.equals (""))
{
Parrten= "yyyyMMddHHmmss"
}
Java.text.SimpleDateFormat sdf=new SimpleDateFormat (parrten)
Java.util.Date cday=new Date ()
Timestr=sdf.format (cday)
Return timestr
}
/ * *
* compare the time of two strings
* @ param T1 time 1
* @ param T2 time 2
* @ param parrten time format: yyyy-MM-dd
* @ return returns long = 0 equality, > 0 T1 > T2
