The JSP gets the session and session emptying of the action and the Judgment _jsp programming

JSP gets the session value problem from the action there are several ways:

For example, I have a session in action ("SessionID", "Sessionvalue")

First, use the struts tag to obtain: <s:property value= "#session. SessionID"/>

Second, <%=request.getsession.getattribute ("SessionID");> session is also one of the built-in objects, you can use the session directly, more convenient than the Request.getsession
It can also be written as <%=session.getattribute ("SessionID");>

III. EL expression get: ${sessionscope.sessionid}

If the value is a bean, it is the same, similar to ${sessionscope.bean.beanproperty}

The general session time is 30 minutes, if you judge whether the session exists

Copy Code code as follows:

<%
String id = "";

String username = "";

User user = (user) Session.getvalue ("Docuser");

Determines whether the user is empty, or if it is not NULL to operate the following. Otherwise, a null pointer exception is reported.
if (user!= null) {
id = User.getid ();

Username = User.getusername ();
}
%>

You can also empty the session
Gets to the session and then sets his value to null

Copy Code code as follows:

<%
Lduser Lduser = (lduser) actioncontext.getcontext (). GetSession (). Get ("Lduser");

if (Lduser = = null) {
Session.putvalue ("Lduser", null);
Out.println ("session to close");
%>