2019独角兽企业重金招聘Python工程师标准>>> 
目前我用的是Struts2的拦截器
1:利用拦截器，配置拦截器 在Struts2中配置
50000000
2：创建LoginInterceptor类 extends AbstractInterceptor
package com.enet.fileter;
import java.net.URLDecoder;
import java.util.Map;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;
import org.apache.struts2.ServletActionContext;
import com.enet.action.UsersAction;
import com.enet.entity.Userinfo;
import com.opensymphony.xwork2.Action;
import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.AbstractInterceptor;
public class LoginInterceptor extends AbstractInterceptor {
@Override
public String intercept(ActionInvocation invaction) throws Exception {
// TODO Auto-generated method stub
HttpSession sessiona = ServletActionContext.getRequest().getSession();
Map session= invaction.getInvocationContext().getSession();
System.out.println(session.toString());
if(UsersAction.class == invaction.getAction().getClass()){
return invaction.invoke();
}
Userinfo sss= (Userinfo)sessiona.getAttribute("user");
Userinfo ss= (Userinfo) ServletActionContext.getRequest().getSession().getAttribute("user");
if(sessiona.getAttribute("user") != null){
return invaction.invoke();
}else{
//若为空，直接跳转到登录页面
return Action.ERROR;
}
}
}
PS:这个session获取的是JSP中的值，不是action中的
3：创建一个UserAction，有登录和登出的方法
public String login(){
HttpServletRequest httpRequest = ServletActionContext.getRequest();
HttpSession httpSession = httpRequest.getSession();
//加密
user.setPassword(MD5Util.MD5(user.getPassword()));
//判断用户名密码是否正确，返回这个用户的对象
Xuser users=biz.getlogin(user);
//查看是否有用户
if(users !=null){
//查看判断是否登录过
if(MyHttpSessionListener.OnLineSession.containsKey(users.getLoginname())){
HttpSession session=MyHttpSessionListener.OnLineSession.get(users.getLoginname());
if(!httpSession.getId().equals(session.getId())){
session.invalidate();
}
}
MyHttpSessionListener.OnLineSession.put(users.getLoginname(), httpSession);
ServletActionContext.getRequest().getSession().setAttribute("user", users);
return SUCCESS;
}else{
return ERROR;
}
}
public String logout(){
return ERROR;
}
我是把用户的名称作为KEY保存到Session中，
现在还有会有错误的，因为你没有写MyHttpSessionListener这个类
4：创建MyHttpSessionListener类 implements HttpSessionListener
package com.enet.fileter;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;
import javax.servlet.annotation.WebListener;
import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpSessionAttributeListener;
import javax.servlet.http.HttpSessionBindingEvent;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;
@WebListener
public class MyHttpSessionListener implements HttpSessionListener {
public static final Map OnLineSession = new HashMap();
private int userNumber;
//获取人数
@Override
public void sessionCreated(HttpSessionEvent event) {
// TODO Auto-generated method stub
userNumber++;
event.getSession().getServletContext().setAttribute("userNumber", userNumber);
}
@Override
public void sessionDestroyed(HttpSessionEvent event) {
HttpSession httpSession = event.getSession();
for (String key : OnLineSession.keySet()) {
if (httpSession.getId().equals(OnLineSession.get(key).getId())) {
OnLineSession.remove(key);
break;
}
}
}
}
PS：这个是清除session中的值，判断key中是否有重复的值