This article has shared with you the specific code for java listener to implement online user statistics for your reference. The specific content is as follows
1. Create a listening class SessionListener in the project and implement the HttpSessionListener interface. The code is as follows
import javax.servlet.http.HttpSessionEvent; import javax.servlet.http.HttpSessionListener; public class SessionListener implements HttpSessionListener { private static int count = 0; public void sessionCreated(HttpSessionEvent se) { count++; System.out.println("session created :" + new java.util.Date()); } public void sessionDestroyed(HttpSessionEvent se) { count--; System.out.println("session destroyed:" + new java.util.D ate()); } public static int getCount() { return count; }}2. Configure web.xml
<listener> <description>session listener</description> <listener-class>com.xxx.SessionListener</listener-class></listener>
3. Show online users in JSP page
<% int count=com.xxx.SessionListener.getCount(); out.println("Number of online users:"+count);%>Note: There are many interfaces for listening sessions in servlets, and their functions are very flexible. The most commonly used are listening sessions and Attributes. Here we want to clarify the concept. There is a difference in the meaning of session listening and Attribute listening in servlets. Session listening does not refer to the placing of a session or destroying a session as we generally understand. This is the function of Attribute listening, because the syntax for placing sessions in servlets is session.setAttribute("session name", the object to be placed). The session listening is an HTTP connection. As long as a user is connected to the server, even if the connection is a blank jsp page, the session event will be triggered. Therefore, the session here actually refers to the connection, which is used to count the current online The number of users is the most suitable.
Is this method of implementing online user counting very special? I hope this article will be helpful and inspiring for everyone's learning.