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Introduction to J2EE

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Background

The Java platform was first introduced in 1995 to address the programming needs for networks and cross-platform programming.
In order to address different needs, Sun Microsystems soon split the Java Technologies into three editions:

Java 2 Platform Micro Edition (J2ME)
Java 2 Platform Standard Edition (J2SE)
Java 2 Platform Enterprise Edition (J2EE)

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J2EE Origin

Sun Microsystems, designed J2EE to define a multi-tier architecture for developing web products to answer the needs from the industry.

Goals:

Reduce the cost and complexity of development.
Allow J2EE applications to be rapidly deployed and easily enhanced.

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J2EE

Is a platform that provides a set of components which enable programmer to Develop, Deploy, and Run Java based web application.

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J2EE Components

As said earlier, J2EE applications are made up of components.
A J2EE component is a self-contained functional software unit that is assembled into a J2EE application with its related classes and files and that communicates with other components

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Components

A web component is a software entity that runs in a J2EE environment to provide responses to external requests.

Client Components .
Server Component :

Web components - Servlets and JSP pages

Enterprise Components – EJB.

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J2EE Containers

J2EE container is a Java runtime environment which is responsible for managing life cycle of J2EE components.

There are five defined container types in the J2EE specification

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J2EE Containers

Three of these are server-side containers:

The server itself, which provides the J2EE runtime environment .
A Web container to manage Servlets and JSP pages
An EJB container to manage EJB components.

The other two container types are client-side:

An application container for stand-alone GUIs.
An applet container, meaning a browser, usually with the Java Plug-in.

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Web App. Layers :

Presentation Layer.
Business Logic Layer.
Data Layer

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Packaging Applications and Components

JAR – Java Archive.
WAR – Web Archive.
EAR – Enterprise Archive.

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Deployment Descriptors

Deployment descriptors are included in the Archives, along with component-related resources

Deployment descriptors are XML documents that describe configuration and other deployment settings .

The statements in the deployment descriptor are declarative instructions to the J2EE container.

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Working with HTML

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What is HTML?

Hyper Text Markup Language

A markup language designed for the creation of web pages and other information viewable in a browser.

The basic language used to write web pages.

File extension:- .htm or .html

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HTML Tags :

Basic HTML Tags.
Text Formatting Tags.
Anchor Tag.
Page Formatting Tags
Image Handling Tag.
Form Tags.
Style Tag.
Script Tag.

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HTML Document Structure

<html>

<head>

<title> Page Title Goes Here </title>

</head>

<body>

content goes here

</body>

</html>

Every HTML document should start with the tag <html> and end with the tag </html>, this tells the browser that this is an HTML document. Each HTML document includes a head and a body. The head includes information about the document (possibly the title, author, date of creation, software used to create the document) and the body contains the content of the document. There are tags used to identify these sections:

<head> </head> these tags surround the head of the document and come first (before the body tags).

<body> </body> these tags surround the content of the document.

The head and body tags are actually required by the latest version of HTML. Within the title tags the document should contain a document title - this title is typically shown in the title bar of the browser window. Document titles should convey something useful about the content of the document.

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Background

bgcolor

Specifies a background-color for a HTML page.

background

Specifies a background-image for a HTML page

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Text

Put text on a webpage

<p>Today is my first day at my new job, I’m so excited!</p>

Output:-

Today is my first day at my new job, I’m so excited!

Put text in center of a page

<center>Hello</center>

Output:-

Hello

Put text on the right of a page

<p align=“right”>Hello</p>

Output:-

Hello

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HTML Tags

For example: <b>, <font>,<title>, <p> etc.
Tag usually goes with pair: an open tag (<b>) and an end tag (<\b>)

Single tag: <hr>,<br>
Tags are NOT case sensitive

Effect	Code	Code Used	What It Does
Bold	B	<B>Bold</B>	Bold
Italic	I	<I>Italic</I>	Italic

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Font

To change text size

<font size="+3">Hello</font>
Output: Hello

To change text color

<font color="red">Hello</font>
Output: Hello

Using both

<font size="+3" color="red">Hello</font>
Output: Hello

Tag attribute

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Commonly Used Character Entities

Result	Description	Entity Name
	Non-breaking space
<	Less than	<
>	Greater than	>
&	Ampersand	&
“	Quotation mark	"
©	Copyright	©

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Headings

There are 6 heading commands.

<H1>This is Heading 1</H1>

<H2>This is Heading 2</H2>

<H3>This is Heading 3</H3>

<H4>This is Heading 4</H4>

<H5>This is Heading 5</H5>

<H6>This is Heading 6</H6>

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List

Unordered list

Code:

<ul>

<li>Coffee</li> <li>Milk</li>

</ul>

Output:-

Coffee
Milk

Ordered list

Code:

<ol>

<li>Coffee</li> <li>Milk</li>

</ol>

Output:-

Coffee
Milk

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Table

<tr>

<th>Heading</th>

<th>Another Heading</th>

</tr>

<tr>

</tr>

<tr>

</tr>

</table>

Heading	Another Heading
Row 1, cell 1	Row 1, cell 2
Row 2, cell 1

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Create Links

A Hypertext link

< a href="http://www.google.com">Google Home</a>

Output:-

Google Home

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Image Formats

.gif

Graphics Interchange Format

.jpeg or .jpg

Joint Photographic Experts Group

.bmp

bitmap

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Inserting Image

Place all images in the same directory/folder where you web pages are
<img src> is a single tag
<img src="image.gif">

Output:-

Turn an image into a hyerlink

</a>

Output:-

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Image Size

Computer images are made up of “pixels”
<IMG HEIGHT="100" WIDTH="150" SRC="image.gif">

Width

Height

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Forms

A form is an area that can contain form elements.
<form></form>
Commonly used form elements includes:

Text fields
Text areas
Combo boxes
Lists
Radio buttons
Checkboxes
Submit buttons
Reset buttons

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Text Input Fields

Used when you want the user to type letters, number, etc.

<form>

First name: <input type="text" name="firstname">

<br>

Last name: <input type="text" name="lastname">

</form>

Output

First name:

Last name:

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Submission Button

When user clicks on the “Submit” button, the content of the form is sent to another file.

Username: <input type="text" name="user">

<br>

</form>

Output:-

Username:

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Checkboxes

Used when you want the user to select one or more options of a limited number of choices.

<form>

I have a bike

<br>

I have a car

</form>

Output:-

I have a bike

I have a car

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Radio Buttons

Used when you want the user to select one of a limited number of choices.

<form>

<input type="radio" name=“gender" value=“Male"> Male

<br>

<input type="radio" name=“gender” value=“Female"> Female </form>

Output:-

Male

Female

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Text Box

Used when you want to get input from user.

<form>

<p>Please provide your suggestion in the text box below:</p>

</textarea>

</form>

Output:-

Please provide your suggestion in the text box below:

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Pull-down Menu

Used when you want user to respond with one specific answer with choices you given.

<p>Select a fruit:</p> <select name"Fruit">�<option selected> Apples�<option> Bananas�< option > Oranges�</select>

Output:-

Select a fruit: