CS320 Lab1

Lab 1. Beans, EL, and JSTL
CS320, Fall 2008

[Q&A] (5pt) Please write down your answers to the following questions on a piece of paper, and show it to the instructor before you proceed to the Programming section.

1. Suppose your account on the CS3 server is cs320stu31, and you have a servlet Foo.java that belongs to a package bar. On the CS3 server, in which directory should you put Foo.class? Where do you put the web.xml file, and what needs to be added to web.xml so that the servlet can be accessed through the URL http://cs3.calstatelae.edu:8080/cs320stu31/FooServlet?

2. Suppose you have a JSP file Foo.jsp. Foo.jsp uses a bean of the class Bar that belongs to the package cs320.stu31. In which directories on the CS3 server should you put Foo.jsp and Bar.class? And what is the URL to access Foo.jsp?

3. A bean Foobar is said to have a write-only property foo, a read-only property bar, and a read/write property fooBar. All properties are of String type. What are the headers of the getter and/or setter methods for these properties? Note that the header of a method includes only the method name, argument(s), and return type, i.e. no method body.

4. Suppose the Foobar bean is declared in a JSP page with <jsp:useBean class="cs320.Foobar" id="fb" />. How do you access the value of the property fooBar in the JSP using EL?

5. What's the difference between the following two lines of code:

<jsp:setProperty name="fb" property="user" value="user" />
<jsp:setProperty name="fb" property="user" param="user" />

6. How do you access the value of a request parameter foobar in a JSP using EL? and how do you check whether the parameter value is null or an empty string?

7. What is the URL to the JSTL Tag Reference documentation?

8. Give an example of using <c:forTokens>.

[Programming] (5pt) Please upload your files to CSNS. The files should include all the source code, documentation (if any), and an HTML file lab1.html, which contains a link to your JSP page on the CS3 server. Note that file uploading will be disabled at 10:30PM, and no submission will be accepted after that.

For this problem you are going to implement an online test application using JSP. The application reads a number of multiple-choice questions from a text file, displays the questions one at a time, and collect the answers from a user. Once the user completes all the questions, the application compares the user solution to the standard solution and displays a score.

A sample file for a test can be downloaded here. The format of the file is as follows:

A test file contains a number of test entries. The exact number of entries is unknown, but we do know that the entries are separated from one another by an empty line.
A test entry consists of exactly five lines: the first line is the question, the next three lines are three possible answers, and the last line is a single letter A, or B, or C, which indicates which answer is the correct answer.

Implement a TestEntry class which consists of at least the following methods:

public TestEntry( String question, String choiceA, String choiceB, String choiceC, String correctAnswer )
public String getQuestion()
public String getChoiceA(), public String getChoiceB(), public String getChoiceC()
public void setAnswer( String ans ) - set the answer to the question by a user
public boolean isAnswerCorrect() - returns true if the user's answer matches the correct answer, or false otherwise.

Implement a bean TestBean which consists of at least the following:

A constructor which reads the test entries from a file, and store them in an ArrayList of TestEntry objects
A read/write property currentTestEntryIndex of type int. This property specifies which test entry is current selected.
A read-only property currentTestEntry of type TestEntry. This property is the currently selected entry.
A read-only property lastEntry of type boolean. The value of this property is true if the currently selected entry is the last entry in the test, or false otherwise.
A read-only property score of type int. The score is calculated as (100 * number_of_correct_answers / number_of_questions) rounded to an integer.

Create a JSP page Test.jsp that uses a session scope TestBean. Test.jsp displays the test entries one at a time, and displays the score when the user completes the test, as shown in the sample displays below. Note that the score is calculated as (the number of correct answers / the total number of questions * 10).

When the page is requested for the first time:	When the page is displaying the last entry:	After the user clicks FINISH:
You may drive off of the paved roadway to pass another vehicle: (A) If the shoulder is wide enough to accommodate your vehicle (B) If the vehicle ahead of you is turning left. (C) Under no circumstances	To avoid last minute moves, you should be looking down the road to where your vehicle will be in about ______________. (A) 5 to 10 seconds (B) 10 to 15 seconds (C) 15 to 20 seconds	Your score is: 80

Hints:

You may use Expression Language to access the properties of a TestEntry object. For example, suppose the id of your TestBean is tb, you can access the question part of the current test entry as ${tb.currentTestEntry.question}.
You may want to use a hidden form field for the index of the "next" entry.
You may use the value of the lastEntry property to decide whether to display NEXT or FINISH.

[PostLab Activities]

Note that although the online test does not provide a PREVIOUS button, a user can always use the Back button on a browser to go back to a previous test entry, and there's no way to prevent the user from doing that because most browsers will cache the previously viewed pages. Can your application handle this case correctly? and if not, how can you fix it?
Generalize your application so it can deal with any number of choices per test entry.
Further generalize your application so it can handle multiple correct answers per test entry.
What if we want to show all the questions in one page? and in that case, how do you collect the answers?