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Questions and Answers

What does the expression ${myBook.price} return if the price property does not exist?

Zero

An error message

An empty string

Null value (correct)

Which of the following notations is used to access nested properties in Expression Language?

${address.student.city}

${student#address.city}

${student.address.city} (correct)

${student[address].city}

What is the purpose of the conditional expression ${test?Opt1, Opt2} in Expression Language?

To access bean properties

To return a list of values

To evaluate and return one of two options based on a condition (correct)

To perform arithmetic operations

How does Expression Language allow access to collection type data?

By using the ${expr1[expr2]} syntax Signup and view all the answers

Which of the following is true regarding the data manipulation capabilities of Expression Language?

It can only retrieve data. Signup and view all the answers

What is the purpose of the action attribute in the HTML form?

To determine where to send the form data after submission Signup and view all the answers

Which JSP directive is mentioned as not resulting in any Servlet code?

Import directive Signup and view all the answers

Where can JSP files be stored?

In any location where an HTML file can be stored Signup and view all the answers

What does the JSP expression scripting element do?

It displays the value of the enclosed expression in string format Signup and view all the answers

What does a JSP declaration element do in the JSP engine?

It inserts Java code into the generated Servlet source code outside any method Signup and view all the answers

What is the correct syntax for a JSP comment scripting element?

<%-- comment --%> Signup and view all the answers

What input does the JSP page expect from the web client?

User name Signup and view all the answers

Which class is specifically mentioned to be imported in the JSP page?

java.util.Date Signup and view all the answers

What role does the JSP engine perform when a page is requested for the first time or has been modified since its last access?

Translates the JSP document to a Servlet Java file Signup and view all the answers

Which of the following is a primary focus of Java Server Pages (JSP)?

Data presentation Signup and view all the answers

What is one of the new features of JSP 2.0 that simplifies web server page authoring?

Expression Language (EL) Signup and view all the answers

In which scenario would the JSP engine compile the Servlet Java file?

When it checks that the page has been modified Signup and view all the answers

How does JSP enhance the capability of web developers when accessing data?

By providing a consistent way to access various data types Signup and view all the answers

What is a key component of the JSP life cycle determined by Servlet technology?

It translates JSP pages into Servlets Signup and view all the answers

What is the primary benefit of using JSP over Servlets?

JSP allows easier HTML writing and maintenance. Signup and view all the answers

What does JSP allow developers to create that adds flexibility to their applications?

Reusable custom tags Signup and view all the answers

Which type of server typically provides JSP engine functionality?

Web server with Servlet container support Signup and view all the answers

Which of the following statements about JSP is TRUE?

JSP allows the embedding of Java code within HTML. Signup and view all the answers

Which statement best describes the separation of concerns in JSP?

JSP allows separation of Java code and HTML presentation. Signup and view all the answers

What element contributes to the easier authoring of web pages in JSP?

The use of JavaBeans. Signup and view all the answers

Which feature of JSP allows it to automatically update without manual recompilation?

Automatic deployment on server. Signup and view all the answers

What do JSP scripting elements primarily help with?

Embedding Java code in HTML. Signup and view all the answers

What does the Expression Language in JSP simplify?

Accessing and manipulating data from Java objects. Signup and view all the answers

What role do custom tags play in JSP?

They promote the reuse of components in JSP applications. Signup and view all the answers

What does the 'jsp:setProperty' action do when a new object is instantiated?

It sets the specified property values of the new bean. Signup and view all the answers

Which attribute is required when using 'jsp:setProperty'?

name Signup and view all the answers

What will happen if both 'value' and 'param' are specified in 'jsp:setProperty' action?

The action will throw an error. Signup and view all the answers

How can the properties of a bean be associated with input parameters?

By using the '*' wildcard character. Signup and view all the answers

What type of value does the 'value' attribute in 'jsp:setProperty' require?

A String that will be converted to the correct type. Signup and view all the answers

What is a common feature of JavaBeans that is utilized in 'jsp:setProperty'?

Binding input parameters to bean properties automatically. Signup and view all the answers

If neither 'param' nor 'value' is specified in 'jsp:setProperty', what does it signify?

The parameter name matches the property name. Signup and view all the answers

How many input request parameters can be mapped to bean properties using 'jsp:setProperty'?

As many parameters as declared properties. Signup and view all the answers

What is the purpose of the doStartTag() method in the WelcomeTag class?

To write output to the client at the start of the tag. Signup and view all the answers

What does the 'namespace' role of the prefix attribute in the taglib directive accomplish?

It distinguishes between different custom tags. Signup and view all the answers

How does the Expression Language (EL) simplify the code for accessing application data?

By using a shorthand notation instead of verbose Java code. Signup and view all the answers

What file defines the custom welcome tag and its mapping to the WelcomeTag class?

myLib.tld Signup and view all the answers

What happens when the myFirst.jsp file is browsed?

The word 'Welcome!' is shown on the screen. Signup and view all the answers

Which statement is true regarding the WelcomeTag class’s exception handling?

It rethrows the exception as a JspException. Signup and view all the answers

What does the term 'empty' refer to in the myLib.tld file related to the welcome tag?

The welcome tag does not take any content. Signup and view all the answers

What is one benefit of using JavaBeans with EL in JSP pages?

It simplifies data access with properties. Signup and view all the answers

Study Notes

CSBP 461 Internet Computing: Java Server Pages (JSP)

Course: CSBP 461, Internet Computing: Java Server Pages (JSP)
Instructor: M. Elarbi Badidi

Objectives

Introduce JSP Web components
Compare JSP with Servlets
Present the JSP life cycle
Introduce JSP scripting elements
Discuss JSP standard actions
Discuss Custom Tags Library
Introduce the Expression Language

Java Server Pages (JSP)

JSP technology allows web developers to generate static and dynamic HTTP content.
JSPs are like ordinary web pages with embedded Java code.
A simple JSP page can be a simple HTML page with a .jsp extension.
Example: ```html

This is a simplest JSP page

``` - The above example is a simple JSP page without any embedded Java code and can be treated as an HTML page.

A Simple JSP Page

Example: ```html

Hello World!
Current time is <%= new java.util.Date() %> ``` - Blue text is static content, red text is dynamic content (outputting current time)

Servlet vs. JSP

Feature	Servlet	JSP
HTML code	In Java	Java-like code in HTML
Authoring	Not easy to author	Very easy to author
Compilation	Code is compiled into a servlet	Code is compiled into a servlet

JSP Benefits

Separates content and display logic
Simplifies web application development, using JSP, JavaBeans, and custom tags
Supports software reuse through components (JavaBeans, custom tags)
Automatic deployment with automatic recompilation when changes are made
Easier to author web pages
Platform independent

Why JSP over Servlet?

Servlets require manual HTML generation and maintenance
JSP streamlines HTML writing and maintenance
JSP supports standard HTML tools (Macromedia DreamWeaver, Adobe GoLive)
Developers can separate content generation (Java) and presentation (HTML) code in JSP

Java Server Pages (JSP) (cont.)

Most JSP pages have embedded Java code enabling server-side data access and business logic implementation.
JSP relies on Servlet container support.
A web server receives a JSP request and converts it into Servlet code, which is compiled and runs in the Servlet container, sending the results back to the client.
JSP focuses on data presentation, while other components (Servlets, JavaBeans, custom tags, EJB) handle business logic.

JSP (cont.)

JSP tag libraries are extensible, allowing developers to create reusable custom tags.
JSP 2.0 features, like Expression Language (EL), improve web page authoring by providing a consistent way to access different data types, including implicit server objects, JavaBeans, Servlets, and remote distributed data.

JSP Life Cycle

JSPs are translated into Java Servlets at runtime.
JSP life cycle is determined by Servlet technology.
A JSP engine is a JSP specification implementation.
When a browser requests a JSP page, the JSP engine checks if the page is updated and translates the JSP page into a Java Servlet and complies it into a class file.
The Servlet container then loads the Servlet class for execution and sends the results back to the client

JSP Initialization

jspInit() method is executed first after the JSP is loaded.
Useful for initializations like database connections.
JSP declaration elements like <%! ... %> are used to declare variables and methods within JSP initialization.

JSP Execution

_service() method is the core method for processing the JSP page.
Java code inside the scripting elements of the JSP are inserted within the _service() method of the Servlet.

JSP Termination

jspDestroy() method is called when the JSP component is unloaded.
Used for resource cleanup (e.g., database disconnections).

First Simple Interactive JSP Example

Example of taking a user name from a web client and presenting a dynamic welcome message.
User input is submitted using a form, forwarding the request to another JSP page. (e.g., helloJsp.jsp)
Input value is captured using request.getParameter("userName")

JSP Syntax Elements

Directives: Define characteristics of the JSP page (e.g., language, import, error handling). Use <%@ ... %>
Declarations: Define variables and methods that can be used inside the JSP page. Use <%! ... %>
Scriptlets: Embedded Java code that performs actions (e.g., calculations, database interactions). Use <% ... %>
Expressions: Display values of expressions. Use <%= ... %>
Comments: Documentation; do not affect output. Use <%-- ... --%> or

JSP Standard Actions

Forward: Redirects a request to another JSP or Servlet page, acting as an internal redirect.
Include: Dynamically includes the contents of another page (HTML/JSP) into the current one.

JSP JavaBeans

JSP pages can use JavaBeans to encapsulate business logic and data, separating HTML generation from Java programming.
Beans provide a way to reuse code and encapsulate complexities.
They are called by jsp:setProperty or jsp:getProperty for setting and getting values

`jsp:useBean` Action Element

Instantiates or gets a reference to a JavaBean.
Specifies the scope of the bean (page, request, session, or application).
Used to create and manage JavaBean objects within JSP pages

`jsp:setProperty` Action Element

Assigns values to bean properties.
Option 1: executes regardless of whether the bean instance exists.
Option 2: executes only if the bean instance does not already exist.

`jsp:getProperty` Action Element

Retrieves the value of a bean property and inserts it into the output.

`jsp:plugin` Action Element

Enables Java Applet execution within a JSP page.

JSP Implicit Variables

application: Represents the ServletContext, providing access to application scope.
config: Represents the ServletConfig, used for configuration parameters.
page: Refers to the page object itself.
session: Represents an HTTP session, enabling session-based operations.
request: Represents the current HTTP request.

Custom Tag Library

Separates HTML authoring from Java programming.
Encapsulates complex Java code to make it reusable and maintainable.
XML descriptor file (tld) maps tags to their implementation classes.
A Java tag handler class handles the custom tags.

JSP 2.0 Expression Language (EL)

Simplifies accessing application data (e.g., bean properties, request parameters).
Uses syntax like ${beanName.propertyName} instead of < %= ... % >.

General Syntax for Bean Access

${expr1.expr2} or ${exprl["expr2"]}

Where expr1 is the bean reference and expr2 is the property of the bean.

Syntax for Collection Data Access

${expr1[expr2]}

Where expr1 is a reference to an array or list, and expr2 is an integer index.

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Description

This quiz covers the fundamentals of Java Server Pages (JSP) as part of the CSBP 461 course. It introduces key components such as JSP life cycle, scripting elements, and custom tags. Students will also explore the differences between JSP and Servlets.

CSBP 461 Java Server Pages (JSP)

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