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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

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