Java Web project, filter determines session failure

Generally, Java Web projects use filters to determine whether a session is invalid. The following example shows how to implement a filter to verify whether a user's session is lost.

Configuration in Web. xml:

<Filter> <filter-Name> filter </filter-Name> <filter-class> com. zyujie. Common. loginfilter </filter-class> </filter> <! -- Servlet specification, cannot use /*. the end of JSP is full or written as/APP /*, this is the case --> <filter-mapping> <filter-Name> filter </filter-Name> <URL-pattern>/* </url-pattern> </filter-Mapping> <session-config> <session-Timeout> 1 </session-Timeout> </session-config>

Filter class:

Package COM. zyujie. common; import Java. io. ioexception; import Java. io. printwriter; import javax. servlet. filter; import javax. servlet. filterchain; import javax. servlet. filterconfig; import javax. servlet. servletexception; import javax. servlet. servletrequest; import javax. servlet. servletresponse; import javax. servlet. HTTP. httpservletrequest; import javax. servlet. HTTP. httpservletresponse; import javax. servlet. htT P. httpsession; public class loginfilter implements filter {public void destroy () {// todo auto-generated method stub} public void dofilter (servletrequest req, servletresponse res, filterchain chain) throws ioexception, servletexception {// todo auto-generated method stubhttpservletrequest request = (httpservletrequest) req; httpservletresponse response = (httpservletresponse) RES; httpsession session = Request. getsession (); // if the session is not empty, you can browse other pages with string url = request. getservletpath (); system. out. println (URL); // specifies the Directory and suffix, which can also be written on the web. in XML, use URL-pattern to intercept if ing if ((! Request. getservletpath (). Equals ("/login. Action "))&&(! Request. getservletpath (). Equals ("/login. jsp "))&&(! Request. getservletpath (). Equals ("/relogin. jsp "))&&(! Request. getservletpath (). equals ("/jquery-1.8.0.min.js") {system. out. println (request. getservletpath (); If (Session. getattribute ("userinfo") = NULL) {session. invalidate (); response. setcontenttype ("text/html; charset = gb2312"); printwriter out = response. getwriter (); out. println ("<script language = 'javascript 'Type = 'text/JavaScript '>"); out. println ("alert ('session becomes invalid because you haven't performed this operation for a long time! Please log on again! '); Window. location. href = '"+ request. getcontextpath () + "/relogin. JSP '"); out. println ("</SCRIPT>");} else {chain. dofilter (request, response) ;}} else {chain. dofilter (request, response) ;}} public void Init (filterconfig arg0) throws servletexception {// todo auto-generated method stub }}

I did a test: All Ajax requests cannot be filtered, and I don't know why. If Ajax needs to determine the session, it can use the Interceptor: Code: (Ajax requests cannot jump to the page, but do not know how to implement this Ajax request, the session is lost, and the page jumps .)

Struts2 configuration, Interceptor:

<package name="myInterceptors" namespace="/system/login" extends="struts-default"><interceptors><interceptor name="timer" class="com.zyujie.common.TimerInterceptor" /><interceptor name="logger" class="com.zyujie.common.LoggerInterceptor" /><interceptor name="sessionFilter" class="com.zyujie.common.SessionFilterInterceptor" /></interceptors><action name="userLogin" class="userLoginAction" method="userLogin">        <interceptor-ref name="logger" />        <interceptor-ref name="timer" /><result name="input" type="redirect">/login.jsp</result><result name="success" type="redirect">/ok.jsp</result>   </action>      <action name="getSession" class="userLoginAction" method="getSession">   <result name="input" type="redirect">/login.jsp</result>   </action><action name="reLogin" class="userLoginAction" method="reLogin"><result name="input" type="redirect">/relogin.jsp</result><result name="success" type="redirect">/ok.jsp</result></action><action name="testSession" class="userLoginAction" method="testSession"><interceptor-ref name="sessionFilter" /><result name="input" type="redirect">/login.jsp</result><result name="success" type="redirect">/ok.jsp</result></action></package>

Interception class:

Package COM. zyujie. common; import Java. io. printwriter; import javax. servlet. HTTP. httpservletresponse; import javax. servlet. HTTP. httpsession; import Org. apache. struts2.servletactioncontext; import COM. opensymphony. xwork2.action; import COM. opensymphony. xwork2.actioninvocation; import COM. opensymphony. xwork2.interceptor. abstractinterceptor; public class sessionfilterinterceptor extends actinterceptor {@ Overridepublic string intercept (actioninvocation Invocation) throws exception {httpsession session = servletactioncontext. getrequest (). getsession (); If (Session. getattribute ("userinfo") = NULL) {// httpservletresponse response = servletactioncontext. getresponse (); // servletactioncontext. getresponse (). sendredirect (action. input); // session. invalidate (); // response. setcontenttype ("text/html; charset = gb2312" ); // Printwriter out = response. getwriter (); // out. println ("<script language = 'javascript 'Type = 'text/JavaScript '>"); // out. println ("alert ('session becomes invalid because you haven't performed this operation for a long time! Please log on again! '); Window. location. href = '/login. JSP '"); // out. println ("</SCRIPT>"); // return "NONE"; Return Action. input;} else {return invocation. invoke ();}}}

For Ajax requests, the page cannot be redirected. Many people say that they only need to determine the return value on the page to jump.