SCWCD认证套题解析3

Question: 21
You need to store a Java long primitive attribute, called customerOID, into the session scope.
Which two code snippets allow you to insert this value into the session? (Choose two.)
A. long customerOID = 47L;
session.setAttribute("customerOID", new Long(customerOID));
B. long customerOID = 47L;
session.setLongAttribute("customerOID", new Long(customerOID));
C. long customerOID = 47L;
session.setAttribute("customerOID", customerOID);
D. long customerOID = 47L;
session.setNumericAttribute("customerOID", new Long(customerOID));
E. long customerOID = 47L;
session.setLongAttribute("customerOID", customerOID);
F. long customerOID = 47L;
session.setNumericAttribute("customerOID", customerOID);

Answer: A, C

Question: 22
A developer for the company web site has been told that users may turn off cookie support in their browsers. What must the developer do to ensure that these customers can still use the web application?
A. The developer must ensure that every URL is properly encoded using the appropriate URL rewriting APIs.
B. The developer must provide an alternate mechanism for managing sessions and abandon the HttpSession mechanism entirely.
C. The developer can ignore this issue. Web containers are required to support automatic URL rewriting when cookies are not supported.
D. The developer must add the string id=<sessionid> to the end of every URL to ensure that the conversation with the browser can continue.

Answer: A

Question: 23
Your web application requires the adding and deleting of many session attributes during a complex use case. A bug report has come in that indicates that an important session attribute is being deleted too soon and a NullPointerException is being thrown several interactions after the fact. You have decided to create a session event listener that will log when attributes are being deleted so you can track down when the attribute is erroneously being deleted. Which listener class will accomplish this debugging goal?
A. Create an HttpSessionAttributeListener class and implement the attributeDeleted method and log the attribute name using the getName method on the event object.
B. Create an HttpSessionAttributeListener class and implement the attributeRemoved method and log the attribute name using the getName method on the event object.
C. Create an SessionAttributeListener class and implement the attributeRemoved method and log the attribute name using the getAttributeName method on the event object.
D. Create an SessionAttributeListener class and implement the attributeDeleted method and log the attribute name using the getAttributeName method on the event object.

Answer: B

Question: 24
As a convenience feature, your web pages include an Ajax request every five minutes to a special servlet that monitors the age of the user's session. The client-side JavaScript that handles the Ajax callback displays a message on the screen as the session ages. The Ajax call does NOT pass any cookies, but it passes the session ID in a request parameter called sessionID. In addition, assume that your webapp keeps a hashmap of session objects by the ID. Here is a partial implementation of this servlet:
10. public class SessionAgeServlet extends HttpServlet {
11. public void service(HttpServletRequest request, HttpServletResponse) throws IOException {
12. String sessionID = request.getParameter("sessionID");
13. HttpSession session = getSession(sessionID);
14. long age = // your code here
15. response.getWriter().print(age);
16. }

... // more code here
47. }

Which code snippet on line 14, will determine the age of the session?
A. session.getMaxInactiveInterval();
B. session.getLastAccessed().getTime() - session.getCreationTime().getTime();
C. session.getLastAccessedTime().getTime() - session.getCreationTime().getTime();
D. session.getLastAccessed() - session.getCreationTime();
E. session.getMaxInactiveInterval() - session.getCreationTime();
F. session.getLastAccessedTime() - session.getCreationTime();

 Answer: F

Question: 25
Which statement is true about web container session management?
A. Access to session-scoped attributes is guaranteed to be thread-safe by the web container.
B. To activate URL rewriting, the developer must use the HttpServletResponse.setURLRewriting method.
C. If the web application uses HTTPS, then the web container may use the data on the HTTPS request stream to identify the client.
D. The JSESSIONID cookie is stored permanently on the client so that a user may return to the web application and the web container will rejoin that session.
 Answer: C

Question: 26
One of the use cases in your web application uses many session-scoped attributes. At the end of the use case, you want to clear out this set of attributes from the session object. Assume that this static variable holds this set of attribute names:
201. private static final Set<String> 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?
A. session.removeAll(USE_CASE_ATTRS);
B. for ( String attr : USE_CASE_ATTRS ) {
session.remove(attr);
}
C. for ( String attr : USE_CASE_ATTRS ) {
session.removeAttribute(attr);
}
D. for ( String attr : USE_CASE_ATTRS ) {
session.deleteAttribute(attr);
}
E. session.deleteAllAttributes(USE_CASE_ATTRS);

 Answer: C

Question: 27
Assume that a news tag library contains the tags lookup and item: lookup Retrieves the latest news headlines and executes the tag body once for each headline. Exposes a NESTED page scoped attribute called headline of type com.example.Headline containing details for that headline. item Outputs the HTML for a single news headline. Accepts an attribute info of type com.example.Headline containing details for the headline to be rendered.Which snippet of JSP code returns the latest news headlines in an HTML table, one per row?
A. <table>
<tr>
<td>
<news:lookup />
<news:item info="${headline}" />
</td>
</tr>
</table>
B. <news:lookup />
<table>
<tr>
<td><news:item info="${headline}" /></td>
</tr>
</table>
C. <table>
<news:lookup>
<tr>
<td><news:item info="${headline}" /></td>
</tr>
</news:lookup>
</table>
D. <table>
<tr>
<news:lookup>
<td><news:item info="${headline}" /></td>
</news:lookup>
</tr>
</table>

 Answer: C

Question: 28
Which JSTL code snippet can be used to perform URL rewriting?
A. <a href='<c:url url="foo.jsp"/>' />
B. <a href='<c:link url="foo.jsp"/>' />
C. <a href='<c:url value="foo.jsp"/>' />
D. <a href='<c:link value="foo.jsp"/>' />

 Answer: C

Question: 29
Assume the scoped attribute priority does NOT yet exist. Which two create and set a new request-scoped attribute priority to the value "medium"? (Choose two.)
A. ${priority = 'medium'}
B. ${requestScope['priority'] = 'medium'}
C. <c:set var="priority" value="medium" />
D. <c:set var="priority" scope="request">medium</c:set>
E. <c:set var="priority" value="medium" scope="request" />
F. <c:set property="priority" scope="request">medium</c:set>
G. <c:set property="priority" value="medium" scope="request" />
 Answer: D, E

Question: 30
You are creating a JSP page to display a collection of data. This data can be displayed in several different ways so the architect on your project decided to create a generic servlet that generates a comma-delimited string so that various pages can render the data in different ways. This servlet takes on request parameter: objectID. Assume that this servlet is mapped to the URL pattern: /WEB-INF/data. In the JSP you are creating, you need to split this string into its elements separated by commas and generate an HTML <ul> list from the data. Which JSTL code snippet will accomplish this goal?
A. <c:import varReader='dataString' url='/WEB-INF/data'>
<c:param name='objectID' value='${currentOID}' />
</c:import>
<ul>
<c:forTokens items'${dataString.split(",")}' var='item'>
<li>${item}</li>
</c:forTokens>
</ul>
B. <c:import varReader='dataString' url='/WEB-INF/data'>
<c:param name='objectID' value='${currentOID}' />
</c:import>
<ul>
<c:forTokens items'${dataString}' delims=',' var='item'>
<li>${item}</li>
</c:forTokens>
</ul>
C. <c:import var='dataString' url='/WEB-INF/data'>
<c:param name='objectID' value='${currentOID}' />
</c:import>
<ul>
<c:forTokens items'${dataString.split(",")}' var='item'>
<li>${item}</li>
</c:forTokens>
</ul>
D. <c:import var='dataString' url='/WEB-INF/data'>
<c:param name='objectID' value='${currentOID}' />
</c:import>
<ul>
<c:forTokens items'${dataString}' delims=',' var='item'>
<li>${item}</li>
</c:forTokens>
</ul>

 Answer: D

 


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