Tomcat9中如何管理session-创新互联
这篇文章主要介绍Tomcat9中如何管理session,文中介绍的非常详细,具有一定的参考价值,感兴趣的小伙伴们一定要看完!
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session相关共有两个类:
StandardSession:默认的session的类,是对session的系统抽象
StandardManager:默认的session管理类,管理session的创建、加载、持久化等
org.apache.catalina.core.StandardContext.startInternal()
protected synchronized void startInternal() throws LifecycleException { ...省略其他代码... Manager contextManager = null; Manager manager = getManager(); if (manager == null) { if (log.isDebugEnabled()) { log.debug(sm.getString("standardContext.cluster.noManager", Boolean.valueOf((getCluster() != null)), Boolean.valueOf(distributable))); } if ((getCluster() != null) && distributable) { try { contextManager = getCluster().createManager(getName()); } catch (Exception ex) { log.error(sm.getString("standardContext.cluster.managerError"), ex); ok = false; } } else { contextManager = new StandardManager(); } } // Configure default manager if none was specified if (contextManager != null) { if (log.isDebugEnabled()) { log.debug(sm.getString("standardContext.manager", contextManager.getClass().getName())); } setManager(contextManager); } ...省略其他代码... public void setManager(Manager manager) { Lock writeLock = managerLock.writeLock(); writeLock.lock(); Manager oldManager = null; try { // Change components if necessary oldManager = this.manager; if (oldManager == manager) return; this.manager = manager; // Stop the old component if necessary if (oldManager instanceof Lifecycle) { try { ((Lifecycle) oldManager).stop(); ((Lifecycle) oldManager).destroy(); } catch (LifecycleException e) { log.error(sm.getString("standardContext.setManager.stop"), e); } } // Start the new component if necessary if (manager != null) { manager.setContext(this); } if (getState().isAvailable() && manager instanceof Lifecycle) { try { ((Lifecycle) manager).start(); } catch (LifecycleException e) { log.error(sm.getString("standardContext.setManager.start"), e); } } } finally { writeLock.unlock(); } // Report this property change to interested listeners support.firePropertyChange("manager", oldManager, manager); } }
在StandardContext的start方法中,会对sessionManager进行实例化,这里是支持Tomcat的集群session,本文以单机session管理为例,即StandardManager,在setManager中会调用StandardManager.start
org.apache.catalina.session.StandardManager.start()
protected synchronized void startInternal() throws LifecycleException { super.startInternal(); // Load unloaded sessions, if any try { load(); } catch (Throwable t) { ExceptionUtils.handleThrowable(t); log.error(sm.getString("standardManager.managerLoad"), t); } setState(LifecycleState.STARTING); } protected String pathname = "SESSIONS.ser"; protected void doLoad() throws ClassNotFoundException, IOException { if (log.isDebugEnabled()) { log.debug("Start: Loading persisted sessions"); } // Initialize our internal data structures sessions.clear(); // Open an input stream to the specified pathname, if any File file = file(); if (file == null) { return; } if (log.isDebugEnabled()) { log.debug(sm.getString("standardManager.loading", pathname)); } Loader loader = null; ClassLoader classLoader = null; Log logger = null; try (FileInputStream fis = new FileInputStream(file.getAbsolutePath()); BufferedInputStream bis = new BufferedInputStream(fis)) { Context c = getContext(); loader = c.getLoader(); logger = c.getLogger(); if (loader != null) { classLoader = loader.getClassLoader(); } if (classLoader == null) { classLoader = getClass().getClassLoader(); } // Load the previously unloaded active sessions synchronized (sessions) { try (ObjectInputStream ois = new CustomObjectInputStream(bis, classLoader, logger, getSessionAttributeValueClassNamePattern(), getWarnOnSessionAttributeFilterFailure())) { Integer count = (Integer) ois.readObject(); int n = count.intValue(); if (log.isDebugEnabled()) log.debug("Loading " + n + " persisted sessions"); for (int i = 0; i < n; i++) { StandardSession session = getNewSession(); session.readObjectData(ois); session.setManager(this); sessions.put(session.getIdInternal(), session); session.activate(); if (!session.isValidInternal()) { // If session is already invalid, // expire session to prevent memory leak. session.setValid(true); session.expire(); } sessionCounter++; } } finally { // Delete the persistent storage file if (file.exists()) { if (!file.delete()) { log.warn(sm.getString("standardManager.deletePersistedFileFail", file)); } } } } } catch (FileNotFoundException e) { if (log.isDebugEnabled()) { log.debug("No persisted data file found"); } return; } if (log.isDebugEnabled()) { log.debug("Finish: Loading persisted sessions"); } } protected void doUnload() throws IOException { if (log.isDebugEnabled()) log.debug(sm.getString("standardManager.unloading.debug")); if (sessions.isEmpty()) { log.debug(sm.getString("standardManager.unloading.nosessions")); return; // nothing to do } // Open an output stream to the specified pathname, if any File file = file(); if (file == null) { return; } if (log.isDebugEnabled()) { log.debug(sm.getString("standardManager.unloading", pathname)); } // Keep a note of sessions that are expired Listlist = new ArrayList<>(); try (FileOutputStream fos = new FileOutputStream(file.getAbsolutePath()); BufferedOutputStream bos = new BufferedOutputStream(fos); ObjectOutputStream oos = new ObjectOutputStream(bos)) { synchronized (sessions) { if (log.isDebugEnabled()) { log.debug("Unloading " + sessions.size() + " sessions"); } // Write the number of active sessions, followed by the details oos.writeObject(Integer.valueOf(sessions.size())); for (Session s : sessions.values()) { StandardSession session = (StandardSession) s; list.add(session); session.passivate(); session.writeObjectData(oos); } } } // Expire all the sessions we just wrote if (log.isDebugEnabled()) { log.debug("Expiring " + list.size() + " persisted sessions"); } for (StandardSession session : list) { try { session.expire(false); } catch (Throwable t) { ExceptionUtils.handleThrowable(t); } finally { session.recycle(); } } if (log.isDebugEnabled()) { log.debug("Unloading complete"); } }
在start方法中,会调用load方法,load方法最终调用doLoad方法,会读取文件名为SESSIONS.ser的文件,该文件存储了Tomcat关闭时session的内容,具体存储逻辑在doUnload方法中
Request.getSession()
public HttpSession getSession() { Session session = doGetSession(true); if (session == null) { return null; } return session.getSession(); } protected Session doGetSession(boolean create) { // There cannot be a session if no context has been assigned yet Context context = getContext(); if (context == null) { return null; } // Return the current session if it exists and is valid if ((session != null) && !session.isValid()) { session = null; } if (session != null) { return session; } // Return the requested session if it exists and is valid Manager manager = context.getManager(); if (manager == null) { return null; // Sessions are not supported } if (requestedSessionId != null) { try { session = manager.findSession(requestedSessionId); //读取session } catch (IOException e) { session = null; } if ((session != null) && !session.isValid()) { session = null; } if (session != null) { session.access(); return session; } } // Create a new session if requested and the response is not committed if (!create) { return null; } boolean trackModesIncludesCookie = context.getServletContext().getEffectiveSessionTrackingModes().contains(SessionTrackingMode.COOKIE); if (trackModesIncludesCookie && response.getResponse().isCommitted()) { throw new IllegalStateException(sm.getString("coyoteRequest.sessionCreateCommitted")); } String sessionId = getRequestedSessionId(); if (requestedSessionSSL) { // If the session ID has been obtained from the SSL handshake then // use it. } else if (("/".equals(context.getSessionCookiePath()) && isRequestedSessionIdFromCookie())) { if (context.getValidateClientProvidedNewSessionId()) { boolean found = false; for (Container container : getHost().findChildren()) { Manager m = ((Context) container).getManager(); if (m != null) { try { if (m.findSession(sessionId) != null) { found = true; break; } } catch (IOException e) { // Ignore. Problems with this manager will be // handled elsewhere. } } } if (!found) { sessionId = null; } } } else { sessionId = null; } session = manager.createSession(sessionId); //创建新的session // Creating a new session cookie based on that session if (session != null && trackModesIncludesCookie) { Cookie cookie = ApplicationSessionCookieConfig.createSessionCookie( context, session.getIdInternal(), isSecure()); response.addSessionCookieInternal(cookie); } if (session == null) { return null; } session.access(); return session; }
在getSession方法中,会先根据sessionId在调用manager.findSession查找,如果查找不存在则会调用manager.createSession创建
findSession() & createSession()
public Session findSession(String id) throws IOException { if (id == null) { return null; } return sessions.get(id); } public Session createSession(String sessionId) { if ((maxActiveSessions >= 0) && (getActiveSessions() >= maxActiveSessions)) { rejectedSessions++; throw new TooManyActiveSessionsException( sm.getString("managerBase.createSession.ise"), maxActiveSessions); } // Recycle or create a Session instance Session session = createEmptySession(); // Initialize the properties of the new session and return it session.setNew(true); session.setValid(true); session.setCreationTime(System.currentTimeMillis()); session.setMaxInactiveInterval(getContext().getSessionTimeout() * 60); String id = sessionId; if (id == null) { id = generateSessionId(); } session.setId(id); sessionCounter++; SessionTiming timing = new SessionTiming(session.getCreationTime(), 0); synchronized (sessionCreationTiming) { sessionCreationTiming.add(timing); sessionCreationTiming.poll(); } return session; }
所有的session为维护在一个HashMap中,在创建时会想Map中维护,读取是从Map中查找。
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文章名称:Tomcat9中如何管理session-创新互联
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