different way for <jsp:useBean>
Question
There is -
<html>
<body>
<jsp:useBean id="user" class="user.UserData" scope="session"/>
</body>
</html>
And -
<html>
<body>
<%
Object user = session.getAttribute("user.UserData") ;
%>
</body>
</html>
Assume user.UserData exists on the session . is there any differnce between the two ways ?
2 answers
solution1
3 ACCPTED 2012-08-02 18:15:29
A well known issue in JSPs is: avoid everything you can on using Java code with your page (.jsp). So the first approach fits better, do you agree? Taglibs <jsp:useBean /> among others are a nice way of accessing code without mixing the layers. This concepts I barely introduced are part of MVC "specification".
-- EDIT --
The second way of acessing a bean is known as scriptlets and should be avoided as always as possible. A brief comparison can be found here JSTL vs jsp scriptlets .
solution2
2 2012-08-02 18:22:35
<jsp:useBean id="user" class="user.UserData" scope="session"/>
is equivalent to
<%
Object userDataObject = session.getAttribute("user") ; // id="user" of <jsp:useBean> maps to session attribute name "user"
%>
Besides, the scriptlet only reads existing data from session or returns null if no attribute is found.
If <jsp:useBean> finds attribute "user" in session to be null, It will create an instance of 'user.UserData' and add to attribute "user" in session scope.
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