隨著Web開發的應用程序變得越來越復雜，我們可以將現有應用程序拆分為多個應用程序，但我們還應該支持新的應用程序擴展，接下來我們就和錯新技術頻道小編一起去看看實例演示tomcat共享多個web應用會話的方法。
tomcat共享多個web應用會話的實現方法
問題
今天有位朋友問了個問題，大致是：tomcat下兩個Java web，一個是商城，一個是直播，從商城登錄后，再跳轉到直播，發現處于非登錄狀態。
解決思路
方案1
重寫獲取session方法即可。
方案2
找了源碼發現已經支持類似遍歷所有context內的會話的形式，首先獲取session時，如果cressContext屬性為true，則會在獲取不到時嘗試遍歷所有context是否存在該sessionid，如果存在則在本context根據sessionid創建自己的session對象。
public HttpSession getSession(boolean create) { if (crossContext) { // There cannot be a session if no context has been assigned yet if (context == null) return (null); // Return the current session if it exists and is valid if (session != null && session.isValid()) { return (session.getSession()); } HttpSession other = super.getSession(false); if (create && (other == null)) { // First create a session in the first context: the problem is // that the top level request is the only one which can // create the cookie safely other = super.getSession(true); } if (other != null) { Session localSession = null; try { localSession = context.getManager().findSession(other.getId()); if (localSession != null && !localSession.isValid()) { localSession = null; } } catch (IOException e) { // Ignore } if (localSession == null && create) { localSession = context.getManager().createSession(other.getId()); } if (localSession != null) { localSession.access(); session = localSession; return session.getSession(); } } return null; } else { return super.getSession(create); } }context（web應用）獲取跨應用session時通過類似下面操作獲取：
request.getSession().getServletContext().getContext("/app2").getAttribute("att2"); 這是因為request會根據cookies的sessionid獲取到session對象，這時不會報找不到，因為前面已經根據其他sessionid創建了一個session對象，然后getContext操作會獲取對應url的context，接著進行會話操作。
public ServletContext getContext(String uri) { // Validate the format of the specified argument if (uri == null || !uri.startsWith("/")) { return null; } Context child = null; try { // Look for an exact match Container host = context.getParent(); child = (Context) host.findChild(uri); // Non-running contexts should be ignored. if (child != null && !child.getState().isAvailable()) { child = null; } // Remove any version information and use the mapper if (child == null) { int i = uri.indexOf("##"); if (i > -1) { uri = uri.substring(0, i); } // Note: This could be more efficient with a dedicated Mapper // method but such an implementation would require some // refactoring of the Mapper to avoid copy/paste of // existing code. MessageBytes hostMB = MessageBytes.newInstance(); hostMB.setString(host.getName()); MessageBytes pathMB = MessageBytes.newInstance(); pathMB.setString(uri); MappingData mappingData = new MappingData(); ((Engine) host.getParent()).getService().findConnectors()[0].getMapper().map( hostMB, pathMB, null, mappingData); child = (Context) mappingData.context; } } catch (Throwable t) { ExceptionUtils.handleThrowable(t); return null; } if (child == null) { return null; } if (context.getCrossContext()) { // If crossContext is enabled, can always return the context return child.getServletContext(); } else if (child == context) { // Can still return the current context return context.getServletContext(); } else { // Nothing to return return null; } }實例演示tomcat共享多個web應用會話的方法今天錯新技術頻道小編就為大家介紹到這里了，看完之后，是不是受益匪淺呢?
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