Shiro - 限制并发人数登录与剔除

import org.apache.shiro.cache.Cache;
import org.apache.shiro.cache.CacheManager;
import org.apache.shiro.session.Session;
import org.apache.shiro.session.mgt.DefaultSessionKey;
import org.apache.shiro.session.mgt.SessionManager;
import org.apache.shiro.subject.Subject;
import org.apache.shiro.web.filter.AccessControlFilter;
import org.apache.shiro.web.util.WebUtils;

import com.agood.pojo.ActiveUser;

import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import java.io.Serializable;
import java.util.Deque;
import java.util.LinkedList;

/**
 * 
 * @Title: KickoutSessionControlFilter.java
 * @Package com.agood.bejavagod.controller.filter
 * @Description: 同一用户后登陆踢出前面的用户
 * Copyright: Copyright (c) 2016
 * Company:Nathan.Lee.Salvatore
 * 
 * @author leechenxiang
 * @date 2016年12月12日 下午7:25:40
 * @version V1.0
 */
public class KickoutSessionControlFilter extends AccessControlFilter {

    private String kickoutUrl; //踢出后到的地址
    private boolean kickoutAfter = false; //踢出之前登录的/之后登录的用户 默认踢出之前登录的用户
    private int maxSession = 1; //同一个帐号最大会话数 默认1

    private SessionManager sessionManager;
    private Cache> cache;

    public void setKickoutUrl(String kickoutUrl) {
        this.kickoutUrl = kickoutUrl;
    }

    public void setKickoutAfter(boolean kickoutAfter) {
        this.kickoutAfter = kickoutAfter;
    }

    public void setMaxSession(int maxSession) {
        this.maxSession = maxSession;
    }

    public void setSessionManager(SessionManager sessionManager) {
        this.sessionManager = sessionManager;
    }

    public void setCacheManager(CacheManager cacheManager) {
        this.cache = cacheManager.getCache("shiro-kickout-session");
    }

    @Override
    protected boolean isAccessAllowed(ServletRequest request, ServletResponse response, Object mappedValue) throws Exception {
        return false;
    }

    @Override
    protected boolean onAccessDenied(ServletRequest request, ServletResponse response) throws Exception {
        Subject subject = getSubject(request, response);
        if(!subject.isAuthenticated() && !subject.isRemembered()) {
            //如果没有登录，直接进行之后的流程
            return true;
        }

        Session session = subject.getSession();
        ActiveUser user = (ActiveUser)subject.getPrincipal();
        String username = user.getUserName();
        Serializable sessionId = session.getId();

        // 同步控制
        Deque deque = cache.get(username);
        if(deque == null) {
            deque = new LinkedList();
            cache.put(username, deque);
        }

        //如果队列里没有此sessionId，且用户没有被踢出；放入队列
        if(!deque.contains(sessionId) && session.getAttribute("kickout") == null) {
            deque.push(sessionId);
        }

        //如果队列里的sessionId数超出最大会话数，开始踢人
        while(deque.size() > maxSession) {
            Serializable kickoutSessionId = null;
            if(kickoutAfter) { //如果踢出后者
                kickoutSessionId = deque.removeFirst();
            } else { //否则踢出前者
                kickoutSessionId = deque.removeLast();
            }
            try {
                Session kickoutSession = sessionManager.getSession(new DefaultSessionKey(kickoutSessionId));
                if(kickoutSession != null) {
                    //设置会话的kickout属性表示踢出了
                    kickoutSession.setAttribute("kickout", true);
                }
            } catch (Exception e) {//ignore exception
            }
        }

        //如果被踢出了，直接退出，重定向到踢出后的地址
        if (session.getAttribute("kickout") != null) {
            //会话被踢出了
            try {
                subject.logout();
            } catch (Exception e) { //ignore
            }
            saveRequest(request);
            
            HttpServletRequest httpRequest = WebUtils.toHttp(request);
            if (ShiroFilterUtils.isAjax(httpRequest)) {
                HttpServletResponse httpServletResponse = WebUtils.toHttp(response);  
                httpServletResponse.sendError(ShiroFilterUtils.HTTP_STATUS_SESSION_EXPIRE);
                return false;
            } else {
                WebUtils.issueRedirect(request, response, kickoutUrl);
                return false;
            }
        }

        return true;
    }
}

首先得要有个过滤器命名为：KickoutSessionControlFilter

然后在shiro.xml中需要这么定义：

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