Java & J2EE Struts with Hibernate Framework

J2EE-STRUTS WITH
HIBERNATE FRAMEWORK
BYMohit Chandra Belwal
B.Tech(C.S.E)-4th year

Why JAVA?
The answer is that Java enables users to develop and
deploy applications on the Internet for servers, desktop
computers, and small hand-held devices. The future of
computing is being profoundly influenced by the Internet,
and Java promises to remain a big part of that future. Java
is the Internet programming language.
Java is a general purpose programming language.
Java is the Internet programming language.

Java, Web, and Beyond






Java can be used to develop Web
applications.
Java Applets
Java Web Applications
Java can also be used to develop
applications for hand-held devices
such as Palm and cell phones

Java's History



Developed by Sun Microsystems
--James Gosling, Bill Joy, Patrick Naughton
Originally named OAK in 1991
Renamed and modified to Java in 1995
First non commercial version in 1994
First Commercial version in late 1995



HotJava









The first Java-enabled Web browser

Java Technology


What is Java?
Java technology is both a programming language and a
platform.

--The Java Programming Language
The Java programming language is a high-level language
that can be characterized by all of the following buzzwords:
-Simple
-Distributed
-Dynamic
-Portable
-Robust

-Object oriented
-Multithreaded
-Architecture neutral
-High performance
-Secure

Java Technology….


Characteristics of Java:


Simple:

Java is partially modeled on C++, but greatly simplified and
improved. Some people refer to Java as "C++--" because it is
like C++ but with more functionality and fewer negative
aspects.

Object Oriented:
Object-oriented programming (OOP) is a popular
programming approach that is replacing traditional procedural
programming techniques.
One of the central issues in software development is how to
reuse code. Object-oriented programming provides great
flexibility, modularity, clarity, and reusability through
abstraction, encapsulation, inheritance, and
polymorphism.

Java Technology….




Distributed:

Distributed computing involves several computers
working together on a network. Java is designed to
make distributed computing easy. Since networking
capability is inherently integrated into Java, writing
network programs is like sending and receiving data to
and from a file.

Multi Threaded:
Multithread programming is smoothly integrated in Java,
whereas in other languages you have to call procedures
specific to the operating system to enable multithreading.

Java Technology….




Dynamic:

Java was designed to adapt to an evolving environment. New
code can be loaded on the fly without recompilation. There is no
need for developers to create, and for users to install, major
new software versions. New features can be incorporated
transparently as needed.

Architecture Neutral:
Write once, run anywhere



With a Java Virtual Machine (JVM), you can write one program
that will run on any platform.

Java Technology….




Portable:

Because Java is architecture neutral, Java programs are
portable. They can be run on any platform without being
recompiled.

High Performance:
The java programs are compiled to portable intermediate
form known as the bytecodes, rather then machine level
instructions and JVM executes them on any machine on
which it is placed. JVM uses the adaptive and JIT
technique that improves performance by converting the
java bytecodes to native machine instructions on the fly.



Java Technology….



Robust:
Java compilers can detect many problems that would first show
up at execution time in other languages.



Java has eliminated certain types of error-prone programming
constructs found in other languages.
Java has a runtime exception-handling feature to provide
programming support for robustness.
Java provides automatic memory management.

Secure:
Java implements several security mechanisms to protect your
system against harm caused by stray programs.

Java Technology….


What is Java?
--The Java Platform
A platform is the hardware or software environment in which a
program runs. Some of the most popular platforms are Microsoft
Windows, Linux, Solaris OS, and Mac OS. Most platforms can be
described as a combination of the operating system and underlying
hardware. The Java platform differs from most other platforms in that
it's a software-only platform that runs on top of other hardware-based
platforms.

The Java platform has two components:

--The Java Virtual Machine
--The Java Application Programming Interface (API)

Java Virtual Machine (JVM)








JVM is part of Java programming
language.
JVM is a software, staying on top of
Operating System, such as UNIX,
Windows NT.
It help Java create high level of portability
by hiding the difference between the
Operating System implementations.
It creates an environment that Java
language lives.

Why JVM?






An ordinary language can not create a
system independent program.
Java’s goal is “Write-Once-Run-Anywhere”.
Java programs are not computer, operating
system dependent.
Need to create an “abstract computer” of
its own and runs on it, a kind of virtual
machine which hiding the different OS
implementations.

Java Runtime Environment (JRE)

How JVM works?







Java programs are compiled into byte code.
JVM interprets and converts Java byte code
into machine code in order to execute on a
CPU.
Most web browser has an integrated JVM to run
applets.
Other JVM tasks include:
 Object creations of Java programs.
 Garbage collection.
 Security responsibility.

Java’s Magic: The Bytecode






JVM keeps a compact set of Byte Code
Instructions in order to interpret byte code
into native binary code.
Java compilers do not translate programs
directly into native binary code, which is
system dependent. Instead, programs are
translated into byte code, just in its midway to a runnable.
JVM interprets these half-cooked byte code
into executable machine code on different
computer systems and platforms.

JIT Compiler





JIT stands for “Just In Time”.
10 years ago, a smart idea was discovered
by Peter Deutsch while trying to make
Smalltalk run faster. He called it “dynamic
translation” during interpretation.
Every time JIT compiler interprets byte
codes, it will keep the binary code in log
and optimize it. Next time, when the same
method is running, the optimized code will
run. Experiments show Java programs
using JIT could be as fast as a compiled C
program.

JIT Example


( Loop with 1000 times )
for(int i=0;i<1000;i++){
do_action( );
}
Without JIT, JVM will interpret do_action()
method 1000 times. (A waste of time!)
With JIT, JVM interprets do_action()
method only once and keeps it in log, and
the binary native code will execute for the
rest 999 loops.

JIT Compiler….
Java Virtual
Machine

Java Compiler

Optimize
d
& Kept in
Log

Compiled
Byte Code

JIT Compiler

Native Machine
Code
Machine

Java Technology….

An overview of the Software Development process

Java Technology….

Through the Java VM, the same application is capable of
running on multiple platforms.

Java Application Programming
Interface (API)


The API is a large collection of ready-made software
components that provide many useful capabilities.



It is grouped into libraries of related classes and
interfaces; these libraries are known as packages.

The API and Java Virtual Machine insulate the program from the
underlying hardware.

Different Editions of Java


Java Standard Edition (J2SE)




Java Enterprise Edition (J2EE)




J2SE can be used to develop client-side standalone
applications or applets.
J2EE can be used to develop server-side applications
such as Java servlets, Java ServerPages, and Java
ServerFaces.

Java Micro Edition (J2ME).


J2ME can be used to develop applications for mobile
devices such as cell phones.

A Simple Java Program
//This program prints Welcome to Java!
public class Welcome {
public static void main(String[] args) {
System.out.println("Welcome to Java!");
}
}

Creating, Compiling, and
Running Programs
Create/Modify Source Code

Source code (developed by the programmer)

}
}

Byte code (generated by the compiler for JVM
to read and interpret, not for you to understand)

…
Method Welcome()
0 aload_0
…
Method void main(java.lang.String[])
0 getstatic #2 …
3 ldc #3 <String "Welcome to
Java!">
5 invokevirtual #4 …
8 return

Saved on the disk

Source Code

Compile Source Code
i.e., javac Welcome.java
If compilation errors
stored on the disk

Bytecode

Run Byteode
i.e., java Welcome

Result
If runtime errors or incorrect result

Trace a Program Execution
Enter main method

}
}

Execute statement

}
}


}
}

print a message to the
console

Starting J2EE

JAVA ENTERPRISE EDITION
(J2EE)

J2EE Concepts :
Definition :
The Java 2 Enterprise Edition (J2EE) is a multi-tiered
architecture for implementing enterprise-class
applications and web based applications.
Model :
It is based on component based application model. In
this model such components use services provided by
the container which would otherwise typically need to
be incorporated in the application code.


Open and standard based platform for

developing, deploying and managing

n-tier, Web-enabled, server-centric, and
component-based enterprise applications

J2EE Features






Component based model
Container provided services
Highly Scalable
Simplified Architecture
Flexible security model

J2EE Benefits




Flexibility of scenarios and support to
several types of clients.
Programming productivity:







Services allow developer to focus on
business
Component development facilitates
maintenance and reuse
Enables deploy-time behaviors
Supports division of labor

J2EE Components






Application clients and applets are
components that run on the client.
Java Servlet and JavaServer Pages
technology components are Web components
that run on the web server. (Web Container)
Enterprise JavaBeans components (enterprise
beans) are business components that run on
the application server. (EJB Container)

J2EE Containers
Definition :
Containers are the interface between a component
and the low-level platform-specific functionality
that supports the component. Ex: Apache Tomcat,
GlassFish
Types :

Enterprise JavaBeans (EJB) container

Web container

Application client container

Applet container

What does container gives you?






Communications Support
Lifecycle Management
Multithreading Support
Declarative Security
JSP Support

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

Components






Client components run on the client
machine, which correlate to the client
containers
Web components -Servlets and JSP
page
EJB Components

Packaging Applications and
Components




Under J2EE, applications and
components reside in Java Archive
(JAR) files
These JARs are named with different
extensions to denote their purpose,
and the terminology is important

Various File types






Enterprise Archive (EAR) files
represent the application, and contain
all other server-side component
archives that comprise the application
Client interface files and EJB
components reside in JAR files
Web components reside in Web
Archive (WAR) files

Deployment Descriptors





Deployment descriptors are included in the
JARs, along with component-related resources
Deployment descriptors are XML documents
that describe configuration and other
deployment settings (remember that the J2EE
application server controls many functional
aspects of the services it provides)
The statements in the deployment descriptor
are declarative instructions to the J2EE
container; for example, transactional settings
are defined in the deployment descriptor and
implemented by the J2EE container

J2EE Application Model






Browser is able to process HTML and
applets pages.
It forwards requests to the web
server, which has JSPs and Servlets
Servlets and JSPs may access EJB
server.

Overview of Servlets









Are container managed web components
Processes HTTP requests (non-blocking call-andreturn)
Loaded into memory once and then called many times
Generate dynamic response to requests from web
based clients
Synchronize multiple concurrent client request
Better alternative to CGI

Efficient

Platform and server independent

Session management

Java-based

Servlet Operation






Servlet is Java program that runs as
separate thread inside servlet
container.
Servlet container is part of web
server
It interact with web client using
response request paradigm.

The Servlet API
ServletConfig
Servlet

GenericServlet

ServletRequest

HttpServlet

HttpServletRequest

ServletResponse

HttpServletResponse

javax.servlet.*

javax.servlet.http.*

48

Servlet example
public class HelloWorldServlet extends HttpServlet {
public void service(HttpServletRequest req,
HttpServletResponse res) throws IOException {
res.setContentType("text/html");
PrintWriter out = res.getWriter();
out.println("<html><head><title>Hello
World Servlet</title></head>");
out.println("<body><h1>Hello
World!</h1></body></html>");
}
}

Overview of JSP






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

The HTML is known as the template text
JSP files must have the extension .jsp

JSP is translated into a Java servlet, which is then
compiled

Servlets are run in the usual way

The browser or other client sees only the resultant
HTML, as usual
Tomcat knows how to handle servlets and JSP pages

Parts of JSP Pages


Directive


Directives affect the servlet class itself. The most useful directive is page,
which lets you import packages.

<%@ page import=“java.util.”, MVCApp.Cart, MVCApp.CartItem” %>


Declaration


The declarations are inserted into the servlet class, not into a method

<%! Iterator it = null; CartItem ci = null; Vector cpi = null;%>


Raw HTML

<html><head><title>Shopping Cart</title></head></html>


Action


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

<jsp:usebean id =“Cart” scope = “session” class = “MVCApp.Cart”/>


Scriplets



The code is inserted into the servlet's service method
This construction is called a scriptlet

<%
Cpi = cart.getCartItems ( );
it = cpi.iterator();
While (it.hasNext()){ci= (Cart Item)it.next();
%>

Parts of JSP Pages


Expression


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

<td<% = ci.getTitle() %></td>
<td align =“right”><%=ci.getQuantity()%></td>



Implicit Objects


JSP provides several predefined objects.

<% string action = request.getParameter(“action”) ; %>

JSP Life Cycle

Process of a JSP page

JSP Life Cycle


(cont.)

JSP initialization


The jspInit() method is executed first after the
JSP is loaded.



If the JSP developer needs to perform any JSPspecific initialization such as database
connections at the beginning this method can be
specified.



The jspInit() is only called once during any JSP
component life time.

JSP Life Cycle


(cont.)

JSP execution
public _service(HttpServletRequest req,
HttpServletResponse res)
is a JSP service method the same as the service()
method of a Servlet class. This method never needs
to be customized. All Java code defined in scripting
elements are inserted in this method by JSP
engine.



JSP termination
<%! public void jspDestroy(){ . . . } %>
This method allows developers to specify resource
cleanup jobs such as database disconnections.

JSP example
<tr> <td width="150"   </td> <td width="550">
<form method="get">
<input type="text" name="username" size="25"> <br>
<input type="submit" value="Submit">
<input type="reset" value="Reset">
</td> </tr>
</form> </table>
<%
if (request.getParameter("username") != null) {
%>
<%@ include file="response.jsp" %>
<%
}
%>
</body>
</html>

JSP Standard Tag Library (JSTL)


JSP 1.2 introduced supported for a special tag library
called the JSP Standard Tag Library (JSTL)



The JSTL saves programmers from having to develop
custom tag libraries for a range of common tasks, such
as if statements, conditional loops etc.



Enables developers to produce more maintainable and
simpler JSP code



Important development for JSP technology

JSTL


The JSP Standard Tag Library groups actions into four
libraries as follows:

Library

Contents

Core

Core functions such as conditional
processing and looping, important data
from external environments etc

Formatting

Format and parse information

SQL

read and write relational database data

XMl

Processing of XML data

JSTL


To use any of these libraries in a JSP, need to declare using the
taglib directive in the JSP page, specifying the URI and the Prefix
Library

Prefix

URI

Core

c

http://java.sun.com/jsp/jstl/core

Formatting

fmt

http://java.sun.com/jsp/jstl/fmt

SQL

sql

http://java.sun.com/jsp/jstl/sql

XMl

xml

http://java.sun.com/jsp/jstl/xml

Example of declaring use of core library:
<%@ taglib

prefix = “c” uri = “http://java.sun.com/jsp/jstl/core %>

JSTL: Example
Example: JSP page using JSTL that outputs 1 to 10 on a webpage
using the <c:forEach> and <c:out> tags of the core library
<%@ taglib uri="http://java.sun.com/jstl/core" prefix="c" %>
<html>
<head>
<title>Count to 10 Example (using JSTL)</title>
</head>
<body>
<c:forEach var="i" begin="1" end="10" step="1">
<c:out value="${i}" />
<br />
</c:forEach>
</body>
</html>

A taglib directive
declare use of core
library
JSTL tag examples

Model-view-controller (MVC) Design
Pattern


MVC helps resolve some of the issues with the single module
approach by dividing the problem into three categories:


Model.




View.




The model contains the core of the application's functionality. The
model encapsulates the state of the application. Sometimes the only
functionality it contains is state. It knows nothing about the view or
controller.
The view provides the presentation of the model. It is the look of the
application. The view can access the model getters, but it has no
knowledge of the setters. In addition, it knows nothing about the
controller. The view should be notified when changes to the model
occur.

Controller.


The controller reacts to the user input. It creates and sets the model.

Model-view-controller (MVC) Design
Pattern

Two Different Models


MVC or JSP Model 1 and Model 2 differ essentially in
the location at which the bulk of the request
processing is performed.

Model 1

Model 2

Model 1


In the Model 1 architecture the JSP page alone is
responsible for processing the incoming request and
replying back to the client.

Model 1






There is still separation of presentation from
content, because all data access is performed
using beans.
Model 1 architecture is perfectly suitable for simple
applications but it may not be desirable for
complex implementations.
Indiscriminate usage of this architecture usually
leads to a significant amount of scriptlets or Java
code embedded within the JSP page

Model 2



A hybrid approach for serving dynamic content.
It combines the use of both servlets and JSP.

Model 2


The servlet:






performs process-intensive tasks.
acts as the controller.
is in charge of the request processing.
creates any beans or objects used by the JSP.
Decides, depending on the user's actions,
which JSP page to forward the request to.

Model 2


The JSP:






generates the presentation layer.
has no processing logic.
Is responsible for retrieving any objects or
beans that may have been previously created
by the servlet.
Extracts the dynamic content from the servlet
for insertion within static templates.

Model 2






Typically results in the cleanest separation
of presentation from content.
Leads to clear delineation of the roles and
responsibilities of the developers and page
designers.
The more complex your application, the
greater the benefits of using the Model 2
architecture should be.

Jakarta Struts Is:


A model-view-controller (MVC) Model 2
implementation that uses servlets and
JavaServer pages (JSP) technology.

Struts, an MVC 2 Implementation






Struts is a set of cooperating classes,
servlets, and JSP tags that make up a
reusable MVC 2 design.
This definition implies that Struts is a
framework, rather than a library.
Struts also contains an extensive tag library
and utility classes that work independently
of the framework.

Request Processing
4

Action

ActionForm

5

3

Model
6

1
Web Browser
displays page

2

Controller

struts-config

8

7

JSP Page

Struts Overview


Client browser


An HTTP request from the client browser
creates an event. The Web container will
respond with an HTTP response.

Struts Overview


Controller






The Controller receives the request from the
browser, and makes the decision where to
send the request.
With Struts, the Controller is a command
design pattern implemented as a servlet
which is ActionServlet.
The struts-config.xml file configures the
Controller.

Struts Overview


Business logic




The business logic updates the state of the
model and helps control the flow of the
application.
With Struts this is done with an Action class
as a thin wrapper to the actual business logic.

Struts Overview


Model state






The model represents the state of the application.
The business objects update the application state.
The ActionForm bean represents the Model state at
a session or request level, and not at a persistent level.
The JSP file reads information from the ActionForm
bean using JSP tags.

Struts Overview


View





The view is simply a JSP file.
There is no flow logic, no business logic, and
no model information -- just tags.
Tags are one of the things that make Struts
unique compared to other frameworks.

The ActionServlet Class




The Struts Controller is a servlet that maps
events (an event generally being an HTTP
post) to classes.
The Controller uses a configuration file so
we don’t have to hard-code the values.










ActionServlet is the Command part of the MVC
implementation.
It is the core of the Framework.
ActionServlet (Command) creates and uses an
Action, an ActionForm, and an ActionForward.
The struts-config.xml file configures the
Command.
During the creation of the Web project, Action
and ActionForm are extended to solve the
specific problem space.



There are several advantages to this approach:






The entire logical flow of the application is in a
hierarchical text file. This makes it easier to view
and understand, especially with large applications.
The page designer does not have to wade through
Java code to understand the flow of the
application.
The Java developer does not need to recompile
code when making flow changes.

The ActionForm Class






ActionForm maintains the session state for the
Web application.
ActionForm is an abstract class that is subclassed for each input form model.
ActionForm represents a general concept of data
that is set or updated by a HTML form. E.g., you
may have a UserActionForm that is set by an
HTML Form.



The Struts framework will:






Check to see if a UserActionForm exists; if not, it will
create an instance of the class.
Set the state of the UserActionForm using
corresponding fields from the HttpServletRequest.

No more request.getParameter() calls. For instance,
the Struts framework will take fname from request
stream and call UserActionForm.setFname().
The Struts framework updates the state of the
UserActionForm before passing it to the business
wrapper UserAction.



Notes:




The struts-config.xml file controls which HTML
form request maps to which ActionForm.
Multiple requests can be mapped to
UserActionForm.

The Action Class






The Action class is a wrapper around the
business logic.
The purpose of Action class is to translate
the HttpServletRequest to the business
logic.
To use Action, subclass and overwrite the
perform() method.

The Action Class





The ActionServlet (Command) passes the
parameterized classes to ActionForm using the
perform() method.
No more request.getParameter() calls.
By the time the event gets here, the input form
data (or HTML form data) has already been
translated out of the request stream and into an
ActionForm class.

The Action Class


Note:





"Think thin" when extending the Action class.
The Action class should control the flow and
not the logic of the application.
By placing the business logic in a separate
package or EJB, we allow flexibility and reuse.

The Action Class






Another way of thinking about Action class is as
the Adapter design pattern.
The purpose of the Action is to "Convert the
interface of a class into another interface the
clients expect."
"Adapter lets classes work together that couldn’t
otherwise because of incompatibility of interfaces"
(from Design Patterns - Elements of Reusable
OO Software by Gof).

The Action Class






The client in this instance is the
ActionServlet that knows nothing about our
specific business class interface.
Struts provides a business interface it does
understand, Action.
By extending the Action, we make our
business interface compatible with Struts
business interface.

The ActionMapping Class




An incoming event is normally in the form
of an HTTP request, which the servlet
Container turns into an
HttpServletRequest.
The Controller looks at the incoming event
and dispatches the request to an Action
class.





The struts-config.xml determines what
Action class the Controller calls.
The struts-config.xml configuration
information is translated into a set of
ActionMapping, which are put into
container of ActionMappings.







The ActionMapping contains the
knowledge of how a specific event maps to
specific Actions.
The ActionServlet (Command) passes the
ActionMapping to the Action class via the
perform() method.
This allows Action to access the
information to control flow.

What is Hibernate?






It is an object-relational mapping
(ORM) solution for Java
We make our data persistent by
storing it in a database
Hibernate takes care of this for us

Object-Relational Mapping




It is a programming technique for
converting object-type data of an
object oriented programming
language into database tables.
Hibernate is used convert object data
in JAVA to relational database tables.

Why Hibernate and not JDBC?


JDBC maps Java classes to database tables (and from
Java data types to SQL data types)



Hibernate automatically generates the SQL queries.



Hibernate provides data query and retrieval facilities
and can significantly reduce development time
otherwise spent with manual data handling in SQL
and JDBC.



Makes an application portable to all SQL databases.

Hibernate vs. JDBC (an example)


JDBC tuple insertion –
st.executeUpdate(“INSERT INTO book
VALUES(“Harry Potter”,”J.K.Rowling”));



Hibernate tuple insertion –
session.save(book1);

Architecture

Hibernate sits between your
code and the database
Maps persistent objects to
tables in the database

End Of Presentation

THANK YOU….

Java & J2EE Struts with Hibernate Framework

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