Spring MVC to JavaEE
Introduction
Yet Another
Enter Enterprise
Web Java
Framework
copyright 2009 Trainologic LTD
Spring MVC –to
Introduction part
JavaEE
1
• Introduction
The Need for JavaEE
• Overview
The MVC Pattern
on the JavaEE Architecture
• JavaEE
Spring MVC
Key Standards
Implementation
• Controllers
• Mapping Request Handlers
• Views
• I18N and Locale Resolvers
• Customizing Look & Feel using Themes
• File Uploading
• Error Handling
• Using Annotations copyright 2009 Trainologic LTD
Introduction to JavaEE
The Need for JavaEE
• JavaSE is a great tool to write all sorts of applications.
• However, enterprise applications’ development using
JavaSE is cumbersome at best and not even feasible in
the worst case.
• JavaEE targets enterprise applications’ development and
greatly eases the process.
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Introduction to JavaEE
What is JavaEE?
• JavaEE is a specification.
• It is actually an umbrella of many specifications that
provide different services to enterprise applications.
• These specifications have two faces:
• An API that enterprise applications can use.
• An API that the Application Server must implement.
• Wait a sec, what is an Application Server anyway?
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Introduction to JavaEE
The Application Server
• Enterprise applications that use JavaEE are usually
deployed on an Application Server.
• The Application Server supports some (or all) of the
JavaEE standards.
• There are many Application Servers in the market, the
most popular are:
• WebSphere (by IBM).
• WebLogic (Oracle – former BEA).
• JBossAS (Redhat – former JBoss).
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Introduction to JavaEE
The Supplied Services
• The JavaEE umbrella defines a number of sub-
specifications that provide many services.
• Some examples:
• Web development – Servlets/ JSP/ JSF.
• Transactions – JTA / JTS.
• Naming – JNDI.
• Web Services – JAX-WS.
• Enterprise business logic layer – EJB.
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Introduction to JavaEE
• The Need for JavaEE
• Overview on the JavaEE Architecture
• JavaEE Key Standards
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Introduction to JavaEE
JavaEE Tiers
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Introduction to JavaEE
JavaEE Architecture
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copyright 2009 Trainologic LTD
Introduction to JavaEE
• The Need for JavaEE
• Overview on the JavaEE Architecture
• JavaEE Key Standards
copyright 2009 Trainologic LTD
Introduction to JavaEE
JavaEE Key Standards
• The key standards of JavaEE are:
• Servlets / JSP / JSF.
• JNDI.
• JTA.
• JAX-WS.
• JCA.
• JavaMail.
• JMS.
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Introduction to JavaEE
Servlets, JSP and JSF
• Servlets, JSP and JSF standards pertain to the Web Tier.
• Servlets are Java classes that can handle HTTP requests
and produce HTTP responses.
• Servlets are the building blocks of every JavaEE web
application.
• Note that JSP & JSF standards are based on Servlets.
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Introduction to JavaEE
Servlet
• It is important to understand that the Servlets model
specifies that only one instance exists per Servlet.
• Hence, concurrent requests to the same Servlet will be
handled by the same instance.
• Did anyone say ‘resource management’?
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copyright 2009 Trainologic LTD
Introduction to JavaEE
JSP
• JSP stands for Java Server Pages.
• JSP is a view technology.
• Although Servlets can be used for generating the
presentation itself, it is not recommended to do so.
• JSP is a template technology in which there is a mix
between template data (HTML & Javascript) and Java
code.
• Let’s see an example…
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Introduction to JavaEE
JSP Example
• Here is an example of a simple JSP:
<HTML>
<BODY>
<%
// This scriptlet declares and initializes "date"
System.out.println("Evaluating the current date");
java.util.Date date = new java.util.Date();
%>
Hello! The time is:
<%
out.println(date);
out.println("<BR>Your machine's address is: ");
out.println(request.getRemoteHost());
%>
</BODY>
</HTML>
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copyright 2009 Trainologic LTD
Introduction to JavaEE
JSF
• JSF stands for Java Server Faces.
• JSF is a web development framework which is
component-based.
• In JSF the page is constructed from a tree of
components.
• JSF defines a life-cycle, event system and API for these
components.
• Many JSF component libraries can be found on the web.
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Introduction to JavaEE
JNDI
• JNDI stands for Java Naming & Directory Interface.
• A Naming Service stores objects by their names.
• A Directory Service stores objects by name and also
associates attributes to them.
• The JNDI standard provides a uniform naming &
directory API which is vendor independent.
• Just like JDBC with relational databases.
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Introduction to JavaEE
JNDI Examples
• Here are some examples of providers that have a JNDI
‘driver’:
• Windows Registry.
• The file system.
• DNS (Domain Name System).
• COS (Common Object Services) – CORBA naming
server.
• LDAP.
• RMI Registry.
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Introduction to JavaEE
The JNDI Architecture
• The JNDI organizes the objects in a tree structure.
• Each node in the tree is called Context.
• A context can have sub-contexts or objects-names
mappings.
• We’ll see how to use the JNDI API in later chapters.
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Introduction to JavaEE
JTA/JTS
• Java Transaction API (JTA) and Java Transaction Service
(JTS) provide distributed transaction services for JavaEE
applications.
• Transaction management is very important and one of
the key factors in the success of the EJB standard.
• We’ll discuss transactions in a later chapter.
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Introduction to JavaEE
JAX-WS
• JAX-WS stands for Java API for XML – Web Services.
• It allows to easily expose POJOs as Web Services.
• Here is an example of a Web Service:
import javax.jws.WebService;
@WebService
public class HelloWorld {
public String sayHello() {
return "Hello World";
}
}
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Introduction to JavaEE
JCA
• JCA stands for J2EE Connector Architecture.
• JCA provides a way to incorporate legacy applications
into the management of the Application Server.
• The Application Server knows all about transaction
management, resource pooling and security.
• So, when integrating with a legacy system, why do we
need to re-invent the wheel (handle connections,
transactions and security for the legacy system)?
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Introduction to JavaEE
JCA
• By writing a special driver (called a Resource Adapter),
you can have the Application Server handle connections,
transactions and security for your legacy system.
• JCA also supports incoming transactions, work
management and has a special connection to Message
Driven Beans.
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Introduction to JavaEE
JavaMail
• JavaMail provides a vendor and protocol independent
framework to handle mail and messaging applications.
• With JavaMail you can receive and send e-mails using
POP3, IMAP and SMTP.
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Introduction to JavaEE
JMS
• Java Message Service provides a uniform vendor-
independent API for messaging systems.
• A messaging system provides asynchronous and reliable
messaging.
• JMS supports both Peer-to-Peer and Publish/Subscribe
modes.
• We’ll discuss JMS in details in the Message Driven Bean
chapter.
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Introduction to JavaEE
EJB
• Hey, didn’t we forget one of the most important
specifications?
• What about EJBs?
• Well, from now on, we’ll discuss nothing else…
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