CS320 F04 Lab1

Lab 1. Beans, EL, and JSTL
CS320, Fall 2004

[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. A bean 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?

2. Suppose a bean belongs to the package cs320.stuxx. In which directory on the CS server should you put the .class file of the bean so your JSP files can use it?

3. Briefly explain the four scopes of a bean in a JSP file. Which scope is the default?

4. 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" />

5. How do you access the value of a request parameter user in a JSP using EL?

6. How do you access the value of a bean property user in a JSP using EL?

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

[Programming] (5pt) Please upload your files using the online turnin server. The files should include all the source code, documentation, and an HTML file lab1.html, which contains a link to your JSP page on the CS server. Note that file uploading will be disabled automatically after 3PM, so please turn in your work on time.

Problem Description. 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 answers from a user. Once the user completes all the questions, the appliction compares the user solution to the stanrdard solution, and displays a score.

Implementation Details.

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

A file contains a number of test entries. The exact number of entries is unknown, but we do know that the entries are seperated 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.

2. 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.

3. Implement a bean TestBean which consistes 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 write-only property answer of type String. This property sets the user's answer to a question.
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.

4. The JSP page should create a session scope bean of TestBean, 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:

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:

Although technically TestEntry is a not bean class, you may use an TestEntry object as if it is a bean. 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.

[Discussion]

Note that although the online test does not provide a PREVIOUS button, a user can always use the Back button of 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 applicaton 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?