CS320 Lab1

Lab 1. Beans, EL, and JSTL
CS320, Spring 2006

[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. In which directory should you put your JSP files

on your own computer?
on the CS server?

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 pages can use it?

3. 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?

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 bean property user in a JSP using EL?

6. How do you access the value of a request parameter user 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 using CSNS. 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 7:40PM, so please turn in your work on time.

For this exercise you are going to create a Calculator.jsp, which implements a simple calculator. When the JSP is requested for the first time, it displays a simple calculator like the following::

0
1	2	3	+
4	5	6	-
7	8	9	=
0			Clear

We will refer to the first row of the table above as the displaying area of the calculator, and the rest of table as the keypad, which consists of ten digit keys and four operator keys. The calculator operates like any regular calculator, where a user may input numbers and perform calculations by clicking on the keys. For example, the following table shows a sequence of clicks and the corresponding displays when a user tries to calculate 192+23-107+5.

Click		1	9	2	+	2	3	-	1	0	7	+	5	=	Clear
Display	0	1	19	192	192	2	23	215	1	10	107	108	5	113	0

Calculator.jsp uses a session scope bean Calculator to perform the actual calculation. The bean consists of at least of the following methods:

A constructor which takes no parameter.
public String getDisplay() - returns a string to be displayed in the displaying area
public void setDigit(String digit) - set the digit clicked by a user
public void setOperator(String operator) - set the operator clicked by a user

Note that

No scripting elements are allowed in the JSP page.
It's tricky to use special characters like +, -, or = as parameter values, so you might want to replace them with regular characters or strings. For example, instead of <a href="Calculator.jsp?operator=+">, you may want to use <a href="Calculator.jsp?operator=add"> instead.