简单的java web 统计在线人数实现方法

来源：互联网发布：linux命令大全chmod 编辑：程序博客网时间：2024/05/17 22:41

建立一个class页面实现ServletContextListener和HttpSessionListener接口

import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;

import com.sun.org.apache.bcel.internal.generic.NEW;

public class OnLineUser implements ServletContextListener,HttpSessionListener{

private int counts;
private ServletContext cxt;
public void contextDestroyed(ServletContextEvent arg0) {
// TODO Auto-generated method stub

}

public void contextInitialized(ServletContextEvent e) {
// TODO Auto-generated method stub
cxt=e.getServletContext();//拿到ServletContext
}

public void sessionCreated(HttpSessionEvent arg0) {
  // TODO Auto-generated method stub
  counts ++;
  cxt.setAttribute("counts", new Integer(counts));//setAttribute(字符串，对象型)
}

public void sessionDestroyed(HttpSessionEvent arg0) {
  // TODO Auto-generated method stub
  counts--;
  cxt.setAttribute("counts", new Integer(counts));
}

}

建立一个servlet 其中共享变量注意:

int counts1 = Integer.parseInt(cxt.getAttribute("counts").toString());//Object型不能直接转换成 Int型，要先转换成String型再转Int型