Introduction to Java

CS 571

Java

The Java code is not directly ran by
the machine. It must be
precompiled by
javac

into Java
bytecode

and then ran by the JVM,
a virtual machine, that interprets
the
bytecode

into machine code.

Java code

javac

Java
bytecode

jvm

Binary

Java 2


Java 2 Standard Edition (J2SE)


What this course focuses on


Basic functionality in console with basic GUI like Swing


Java 2 Enterprise Edition (J2EE)


Fully loaded enterprise specific architecture


Only specification, vendors must provide application
servers that meet the specifications as they see fit

J2SE versions


J2SE is a free product provided by Sun Microsystems


J2SE is the basic building block of EVERY Java project
you will ever do


J2SE features have changed from version to version, we
are on Java 1.6 update 11.


There were major changes in the 1.5 release.


Introduction of Java Generics


Tons of new features for concurrency

J2EE Architecture

Databases

Data tier

Java Database Connectivity (JDBC)

Persistence

[ Hibernate ]

Middle tier

Enterprise Java Beans (EJB)

[Stateless Session,
Stateful

Session, Message driven JMS]

Web services

Web tier

HTML

Javascript

[ DOJO, JSON ]

Java Server Faces (JSF)

Java Server Pages (JSP)

Servlets

Other Java stuff


Mobile Edition (Sun)


Java Open GL (JOGL)


And many more…

Java development


You can simply develop any J2SE application by
compiling Java files over
javac
, the Java compiler


Just like C/C++, Java has a build tool, ant.


Integrated Development Environments (IDEs) will do
syntax coloring, code completion, refactoring and
much, much more. The following is a list of free IDEs:


Eclipse


Netbeans

(Sun)


Jbuilder

(formerly Borland)

J2EE infrastructure


If J2EE is only a specification, do you have to build
everything? No! The following Application Servers
(
AppServers
) will provide you the resources to run your
J2EE solutions:


JBoss

(Red Hat)


Glassfish (Sun)


WebSphere

(IBM)


Weblogic

(BEA, now Oracle who has also OC4J)


JOnAS

(open source)


NetWeaver

AS (SAP)


Geronimo (Apache)


JRun

(Adobe)

Other related servers


Apache Tomcat is an
appserver

that only serves up
servlets
.


Apache HTTPD and other servers serves up only
HTML based pages


Many more technology specific servers exist, i.e. PHP