A developer has created a web application that includes a servlet for each use case in the application.These servlets have become rather difficult to maintain because the request processing methods havebecome very large. There is also common processing code in many servlets because these use cases arevery similar.
Which two design patterns can be used together to refactor and simplify this web application？（）

You need to store a floating point number，called Tsquare，in the session scope.
Which two code snippetsallow you to retrieve this value？（）

Given an HttpServletRequest request：
22.String id = request.getParameter（"jsessionid"）；
23.// insert code here
24.String name = （String） session.getAttribute（"name"）；
Which three can be placed at line 23 to retrieve anexisting HttpSession object？（）

One of the use cases in your web application uses many session-scoped attributes. At the end of the usecase，you want to clear out this set of attributes from the session object. Assume that this static variableholds this set of attribute names：
201.private static final Set USE_CASE_ATTRS； 
202.static {
203.USE_CASE_ATTRS.add（"customerOID"）；
204.USE_CASE_ATTRS.add（"custMgrBean"）；
205.USE_CASE_ATTRS.add（"orderOID"）；
206.USE_CASE_ATTRS.add（"orderMgrBean"）；
207.}
Which code snippet deletes these attributes from the session object？（）