Java Jsp Presentation

7/27/2019 Java Jsp Presentation

1/24

Softsmith Infotech 1

JSP

Java Server Pages


2/24


Java Server Pages

JSP (Java Server Pages) is an alternate way of creating servlets

JSP is written as ordinary HTML, with a little Java mixed in

The Java is enclosed in special tags, such as

The HTML is known as the template text

JSP files must have the extension .jsp

JSP is translatedinto a Java servlet, which is then compiled

Servlets are run in the usual way

The browser or other client sees only the resultant HTML, asusual

Tomcat knows how to handle servlets and JSP pages


3/24


Jsp Execution


4/24


JSP scripting elements

There is more than one type of JSP tag, depending on what you want

done with the Java

The expression is evaluated and the result is inserted into the HTML

page

The code is inserted into the servlet's service method

This construction is called a scriptlet

The declarat ions are inserted into the servlet class, not into a method


5/24


Example JSP

Hello! The time is now

Notes:

The tag is used, because we are computing a value

and inserting it into the HTML

The fully qualified name (java.util.Date) is used, instead of the

short name (Date), because we havent yet talked about how to

do import declarations


6/24


Variables

You can declare your own variables, as usual

JSP provides several predefined variables

request : The HttpServletRequest parameter

response : The HttpServletResponse parameter

session : The HttpSession associated with the request, ornull ifthere is none

out : A JspWriter (like a PrintWriter) used to send output to the

client

Example:

Your hostname:


7/24


Scriptlets

Scriptlets are enclosed in tags

Scriptlets do notproduce a value that is inserted directly into theHTML (as is done with )

Scriptlets are Java code that maywrite into the HTML

Example:

Scriptlets are inserted into the servlet exactly as written, and are notcompiled until the entire servlet is compiled

Example:

Have a nice day!

Have a lousy day!


8/24


Declarations

Use for declarations to be added to your servlet class, not

to any particular method

Caution: Servlets are multithreaded, so nonlocal variables must

be handled with extreme care

If declared with, variables are local and OK Data can also safely be put in the request orsession objects

Example:

Accesses to page since server reboot:

You can use to declare methods as easily as to declare

variables


9/24


Directives

Directives affect the servlet class itself

A directive has the form:

or

The most useful directive is page, which lets you import

packages Example:


10/24


JSP Comments

Different from HTML comments.

HTML comments are visible to client.

JSP comments are used for documenting JSP code .

JSP comments are not visible client-side.


11/24


The include directive

The include directive inserts another file into the file being parsed

The included file is treated as just more JSP, hence it can

include static HTML, scripting elements, actions, and directives

Syntax:

The URL is treated as relative to the JSP page If the URL begins with a slash, it is treated as relative to the

home directory of the Web server

The include directive is especially useful for inserting things like

navigation bars


12/24


Actions

Actions are XML-syntax tags used to control the servlet engine

Inserts the indicated relative URL at execution time (not at

compile time, like the include directive does)

This is great for rapidly changing data

Jump to the (static) URL or the (dynamically computed)

JavaExpressionresulting in a URL


13/24


JSP in XML

JSP can be embedded in XML as well as in HTML

Due to XMLs syntax rules, the tags must be different(but they do the same things)

HTML:

XML: expression

HTML: XML: code

HTML:

XML: declarations HTML:

XML:


14/24


Action useBean tag

The useBean action tag is the most commonly used

tag because of its powerful features.

It allows a JSP to create an instance or receive an

instance of a Java Bean. It is used for creating or instantiating a bean with a specific

name and scope.

Examples


15/24


Session in jsp

In session management whenever a request comes for any

resource, a unique token is generated by the server and

transmitted to the client by the response object and stored on the

client machine as a cookie.

Session management

(i) Session Object

(ii) Cookies

(iii) Hidden Form Fields

(iv) URL Rewriting


16/24


Javascript


17/24


JavaScript language

The JavaScript language is an interpreted, object oriented basedscripting language.

JavaScript coding statements are commonly embedded inside a

webpage using the HTML tags .

When the web browser is rendering the webpage, any JavaScriptcoding statements encountered are immediately interpreted and run

before the rendering continues.


18/24


Where to use JavaScript

Verify the end user input data contains legitimate data values.

Handle any arithmetic or logic processing that needs to be executed

on the web browser.

Directly manipulate the web browser objects such as the status bar,

address bar, and the web browser's rendered controls (such astextboxes, selection lists, etc...).

Handle and process client-side events that have been generated.


19/24


How to run JavaScripts

JavaScript statements are interpreted and run by the web browser

Most common web browsers contain a JavaScript interpreter program

interpret and run the JavaScript commands that have been embeddedinside a webpage.

Question1: In a web application, which entity executes JSPs?

Question2: In a web application, which entity executes JavaScript commands?


20/24


JavaScript programming example

2 JavaScript Example1

3

4 Javascript Example1

5 An alert box will appear using the window object

67 8 window.alert("hello world");9 10

11 Goodbye!12

13

14


21/24


Events

An eventis an identifiable occurrence or action that has taken place in

the system. Writing programs that generate and handle events is

known as event programming.

Events are typically generated in the following ways.

GUI programs can generate an event to indicate there has beensome interaction between the widget and the end user.

when an end user presses a button, a click event is generated.

Input/output programs can generate an event to indicate an

input/output event has occurred.

A mouse event is generated when the end user moves themouse.


22/24


Binding Events


23/24


Binding Events

In client side web programming, the web browsercontains

it's own event listener.

Therefore you must do two things

in order to process an event that has been generated.

1. Write the code that binds the event to the event handler.

2. Write the code for the event handler.


24/24


Common web browser events

Event Description

click Used to indicate an entity (usually a control) has been clicked

submit Used to indicate the submit button has been pushed

mouseover Used to indicate the mouse cursor has been moved over the entity. Typically the entity is a control

or an anchor.

mouseout Used to indicate the mouse cursor has been moved away from the entity. Typically the entity is a

control or an anchor.

load Used to indicate the webpage has been completely parsed and loaded into the web browser.

unload Used to indicate the webpage has been unloaded from the web browser. Unloading a webpage

occurs when the web browser is about to load another webpage. The unload event is the last event

that will be generated from the current webpage before the next webpage is loaded. When the web

browser is closed or exited, the unload event is not generated.

Java Jsp Presentation

Documents

Transcript of Java Jsp Presentation