shiro源码篇 - shiro的session的查询、刷新、过…

private void enableSessionValidationIfNecessary() {
    // 获取session验证调度器
    SessionValidationScheduler scheduler = getSessionValidationScheduler();
    // session验证调度器开启 && (调度器为空或调度器不可用)
    if (isSessionValidationSchedulerEnabled() && (scheduler == null || !scheduler.isEnabled())) {
        enableSessionValidation();        // 开启session验证
    }
}

protected synchronized void enableSessionValidation() {
    SessionValidationScheduler scheduler = getSessionValidationScheduler();        // 获取调取器
    if (scheduler == null) {
        scheduler = createSessionValidationScheduler();                            // 创建调取器，实际类型是ExecutorServiceSessionValidationScheduler
        setSessionValidationScheduler(scheduler);                                // 将调度器绑定到sessionManager
    }
    // it is possible that that a scheduler was already created and set via 'setSessionValidationScheduler()'
    // but would not have been enabled/started yet
    if (!scheduler.isEnabled()) {
        if (log.isInfoEnabled()) {
            log.info("Enabling session validation scheduler...");
        }
        scheduler.enableSessionValidation();                                    // 启动定时任务，验证session
        afterSessionValidationEnabled();                                        // 什么也没做，供继承，便于拓展
    }
}

public void enableSessionValidation() {
    if (this.interval > 0l) {
        // 创建ScheduledExecutorService
        this.service = Executors.newSingleThreadScheduledExecutor(new ThreadFactory() {  
            private final AtomicInteger count = new AtomicInteger(1);

            public Thread newThread(Runnable r) {  
                Thread thread = new Thread(r);  
                thread.setDaemon(true);  
                thread.setName(threadNamePrefix + count.getAndIncrement());
                return thread;  
            }  
        });
        //  初始化service interval时长之后开始执行this的run方法，每隔interval执行一次；注意interval的单位是TimeUnit.MILLISECONDS
        this.service.scheduleAtFixedRate(this, interval, interval, TimeUnit.MILLISECONDS);    // this就是ExecutorServiceSessionValidationScheduler自己
    }
    this.enabled = true;
}

/**
 * @see ValidatingSessionManager#validateSessions()
 */
public void validateSessions() {
    if (log.isInfoEnabled()) {
        log.info("Validating all active sessions...");
    }

    int invalidCount = 0;

    // 从sessionDao中获取全部的session
    // sessionDao可以是默认的MemorySessionDAO，也可以是我们定制的CachingSessionDAO
    Collection<Session> activeSessions = getActiveSessions();

    if (activeSessions != null && !activeSessions.isEmpty()) {
        // 一个一个校验
        for (Session s : activeSessions) {
            try {
                //simulate a lookup key to satisfy the method signature.
                //this could probably stand to be cleaned up in future versions:
                SessionKey key = new DefaultSessionKey(s.getId());
                validate(s, key);        // 真正校验的方法
            } catch (InvalidSessionException e) {
                if (log.isDebugEnabled()) {
                    boolean expired = (e instanceof ExpiredSessionException);
                    String msg = "Invalidated session with id [" + s.getId() + "]" +
                            (expired ? " (expired)" : " (stopped)");
                    log.debug(msg);
                }
                invalidCount++;            // 统计上次到这次定时任务间隔内过期的session个数
            }
        }
    }

    if (log.isInfoEnabled()) {
        String msg = "Finished session validation.";
        if (invalidCount > 0) {
            msg += "  [" + invalidCount + "] sessions were stopped.";
        } else {
            msg += "  No sessions were stopped.";
        }
        log.info(msg);
    }
}

protected void validate(Session session, SessionKey key) throws InvalidSessionException {
    try {
        doValidate(session);                    // 真正校验session
    } catch (ExpiredSessionException ese) {
        onExpiration(session, ese, key);        // 从sessionDao中删除过期的session
        throw ese;                                // 抛出异常供上层统计用
    } catch (InvalidSessionException ise) {
        onInvalidation(session, ise, key);        // 从sessionDao中删除不合法的session
        throw ise;                                // 抛出异常供上层统计用
    }
}

protected void doValidate(Session session) throws InvalidSessionException {
    if (session instanceof ValidatingSession) {
        ((ValidatingSession) session).validate();        // 校验session是否过期
    } else {                                            // 若session不是ValidatingSession类型，则抛出IllegalStateException异常
        String msg = "The " + getClass().getName() + " implementation only supports validating " +
                "Session implementations of the " + ValidatingSession.class.getName() + " interface.  " +
                "Please either implement this interface in your session implementation or override the " +
                AbstractValidatingSessionManager.class.getName() + ".doValidate(Session) method to perform validation.";
        throw new IllegalStateException(msg);
    }
}

public void validate() throws InvalidSessionException {
    //check for stopped:
    if (isStopped()) {                    
    // sesson已经停止了，则抛出StoppedSessionException；理论上来讲不会出现这种情况，但程序的事没有100%保障
        //timestamp is set, so the session is considered stopped:
        String msg = "Session with id [" + getId() + "] has been " +
                "explicitly stopped.  No further interaction under this session is " +
                "allowed.";
        throw new StoppedSessionException(msg);
    }

    //check for expiration
    if (isTimedOut()) {     // 校验是否过期，校验方法是：lastAccessTime是否小于(当前时间 - session有效时长)
        expire();            // 更新session的stopTimestamp为当前时间，session的expired为true

        //throw an exception explaining details of why it expired:
        Date lastAccessTime = getLastAccessTime();
        long timeout = getTimeout();

        Serializable sessionId = getId();

        DateFormat df = DateFormat.getInstance();
        String msg = "Session with id [" + sessionId + "] has expired. " +
                "Last access time: " + df.format(lastAccessTime) +
                ".  Current time: " + df.format(new Date()) +
                ".  Session timeout is set to " + timeout / MILLIS_PER_SECOND + " seconds (" +
                timeout / MILLIS_PER_MINUTE + " minutes)";
        if (log.isTraceEnabled()) {
            log.trace(msg);
        }
        throw new ExpiredSessionException(msg);    // 抛出ExpiredSessionException供上层使用
    }
}