监听器实例：
package com.gwssi.listener; import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener; public class SessionListener implements HttpSessionListener { @Override
public void sessionCreated(HttpSessionEvent event) {
HttpSession session = event.getSession();
SessionBean sessionBean = SessionFactory.getInstance().getSessionBean();
System.out.println("sessionCreated session: " + (session.getId()));
System.out.println("sessionCreated accessCount: "
+ (sessionBean.getAccessCount()));
// 访问次数
sessionBean.setAccessCount(sessionBean.getAccessCount() + 1);
// 在线人数统计
sessionBean.getOnline().put(session.getId(), null);
} @Override
public void sessionDestroyed(HttpSessionEvent event) {
HttpSession session = event.getSession();
SessionFactory factory = SessionFactory.getInstance();
SessionBean sessionBean = factory.getSessionBean(); System.out.println("sessionDestroyed session: " + (session.getId()));
System.out.println("sessionDestroyed accessCount: "
+ (sessionBean.getAccessCount())); factory.removeLogin(session);
} }
package com.gwssi.listener;
import javax.servlet.http.HttpSession;
public class SessionFactory {
private SessionBean sessionBean = new SessionBean();
private static SessionFactory factory;
private SessionFactory() {
}
static {
factory = new SessionFactory();
}
public synchronized static SessionFactory getInstance() {
if (factory == null) {
factory = new SessionFactory();
}
return factory;
}
public void addLogin(HttpSession session, String user) {
this.getSessionBean().getOnline().put(session.getId(), user);
this.getSessionBean().getLogin().add(user);
}
public void removeLogin(HttpSession session) {
this.getSessionBean().getLogin()
.remove(this.getSessionBean().getOnline().get(session.getId()));
this.getSessionBean().getOnline().remove(session.getId());
}
public boolean isOnline(String user) {
return this.getSessionBean().getLogin().contains(user);
}
public SessionBean getSessionBean() {
return sessionBean;
}
public void setSessionBean(SessionBean sessionBean) {
this.sessionBean = sessionBean;
}
}
package com.gwssi.listener; import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set; public class SessionBean { private Map<String, String> online = new HashMap<String, String>(); private int accessCount = 0; private Set<String> login = new HashSet<String>(); /**
*
* 返回当前系统在线人数
*
* @return int
*/
public int getOnlineCount() {
return this.online.size();
} /**
* 返回当前系统登录人数
*
* @return int
*/
public int getLoginCount() {
return this.getLogin().size();
} public Map<String, String> getOnline() {
return online;
} public void setOnline(Map<String, String> online) {
this.online = online;
} public int getAccessCount() {
return accessCount;
} public void setAccessCount(int accessCount) {
this.accessCount = accessCount;
} public Set<String> getLogin() {
return login;
} public void setLogin(Set<String> login) {
this.login = login;
} }
在web.xml中增加
<session-config>
<session-timeout>10</session-timeout>
</session-config> <listener>
<listener-class>com.gwssi.listener.SessionListener</listener-class>
</listener>
在登录时
//添加进入SessionFactory，以供记录是否在线
SessionFactory.getInstance().addLogin(session, userInfo.getUserId());
页面调用：
import="com.oddel.listener.SessionFactory;
SessionFactory.getInstance().isOnline(userid)
返回true表示用户当前是在线的。
返回false表示用户当前是不在线的。
参考博客：
http://www.cnblogs.com/sherryueda/p/4273169.html
过滤器：
package com.gwssi.filter; import java.io.IOException; import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession; import cn.gwssi.csdb.fbk.util.StringUtil; public class SessionCheckFilter implements Filter { @Override
public void destroy() {
} @Override
public void doFilter(ServletRequest req, ServletResponse res,
FilterChain chain) throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) req;
String userid = request.getParameter("userid");
// System.out.println(request.getServletPath() + "===SessionCheckFilter====" + userid);
if (StringUtil.isEmpty(userid) || "null".equals(userid)) {
// 当请求中没有userid参数时，由后台进行判断
chain.doFilter(req, res);
} else {
HttpSession session = request.getSession();
UserInfo userInfo = (UserInfo) session.getAttribute("userInfo");
HttpServletResponse response = (HttpServletResponse) res;
if (userInfo == null) {
// session过期
redirect(request, response);
} else { System.out.println(userInfo.getUserId() + "========" + userid);
if (userid.equals(userInfo.getUserId())) {
chain.doFilter(req, res);
} else {
// 登录名不一致
redirect(request, response);
}
}
}
} private void redirect(HttpServletRequest request,
HttpServletResponse response) throws IOException {
String requestType = request.getHeader("X-Requested-With");
if (requestType != null && requestType.equals("XMLHttpRequest")) {
response.setStatus(HttpServletResponse.SC_FORBIDDEN);
} else {
String href = request.getContextPath()
+ "/pages/sessionTimeOut.jsp";
response.sendRedirect(href);
}
} @Override
public void init(FilterConfig config) throws ServletException {
} }
在web.xml中
<filter>
<filter-name>sessionCheckFilter</filter-name>
<filter-class>com.gwssi.csdb.fbk.authority.SessionCheckFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>sessionCheckFilter</filter-name>
<url-pattern>*.do</url-pattern>
</filter-mapping>
参考博客：
http://www.cnblogs.com/sherryueda/p/4275805.html