Download JDBC & Servlets/JSP

Indy Java User’s Group
March 27, 2001
Sallie Mae
6:00p.m
Mission Statement
Promote the use of the Java language
and components across all levels of
interest in the greater Indianapolis
area, by serving as a resource for
knowledge, experience and career
opportunities.
Agenda
•Pizza Welcome!!
6:00-6:15
•Announcements
6:15-6:30
•Joe Caron
6:30-7:30
•Quality Tip
7:30-7:45
•Performance Tip
7:45-8:00
Announcements
•Next Meeting - April 24, 2002
•Mike Burba – Sun ONE
•Java Jam - Kurt Kirkham
•Feedback Results
•eGroups.yahoo.com
•http://groups.yahoo.com/group/indyJug
•http://groups.yahoo.com/group/indyjug_opensource
•BOT Contest – Deadline March 31
•http://developer.digi-net.com
Announcements
CRN – Annual Survey
1) Call 1-800-939-6206
2) Ask for Amy Johnson
3) Request your gift –
•Sweatshirt
•Cap
•T-Shirt
Visit www.metafacts.com
Visit www.crn.com
Presentation Lineup
•Mark Steenbarger
•Indy Jug
•Joe Caron
•KingArthurFlour.com
•Mike Slattery
•SearchSoft.net
•Frank Morton
•Base2Inc.com
Joe Caron
Indianapolis Java Users Group
March 27, 2002
JDBC &
Servlets/JSP
Database access
through the web





Sample application overview
JDBC Fundamentals
Servlet/JSP Fundamentals
Implementation & sample code
Pitfalls, Surprises, Work-arounds
Sample Application





Message Board
Membership Based
Pass membership info to catalogue
site for “quick check-out”
Accumulate “bakers points”
redeemable against online orders
Member “recipe box”
Sample Application





JSP for presentation
Servlets & other java for app logic
MySQL as the RDBMS
Tomcat as Servlet/JSP container
Linux (Red Hat 6.2)
Sample Application





www.bakingcircle.com
Staging Server
Entity Relationship Diagram
Application Diagram
Presentation Diagram
JDBC Fundamentals




Standard means of accessing any
RDBMS for which there is a JDBC
driver
Drivers which implement Sun’s
JDBC standard capture a DB
connection as Java Object
Change DBMS without changing
any application code (except driver)
Sun JDBC API overview
JDBC Fundamentals

Key objects
 Connection
 Statement
 PreparedStatement
 ResultSet
/ Rowset
 ResultSet MetaData
 DB MetaData
JDBC Fundamentals







Sun JDBC overview
Basic Example - MySQL
Basic Example - ORACLE
Statement vs. PreparedStatement
Stand-Alone Example
API Documentation
JDBC Optional: DataSource
Servlet/JSP
Fundamentals



“Servlet Container” (Tomcat, for
example), working in conjunction
with Web server (Apache or IIS)
Integrated in J2EE compliant
server (BEA, Iplanet, Orion)
Many options regarding both the
products and how to set them up
Servlet/JSP Fundamentals
Common Set-Up
Redirect
based on
conf file
Servlet
Engine
Web
Server
.jsp &
/servlet/
Common directory
structure
Client
.html &
others
Servlet/JSP
Fundamentals






Servlets like any other Java class,
except:
Must extend HttpServlet
Must contain a doPost or doGet
method
Come equipped to handle the
laborious points of http
Http requests and responses are
made into Java objects
Best alternative to traditional CGI
Servlet/JSP Fundamentals

Anatomy of a Servlet
 Optional
init method, executes the first
time a servlet is invoked
 doGet/doPost methods execute when
request is made
 method signature accepts http request
and response as parameters
 Optional destroy method
 www.servlets.com Samples
Servlet/JSP
Fundamentals




One instance of Servlet for each
Servlet name
Same instance serves all requests
to that name
Instance members persist across
all requests to that name.
Local /block variables in doPost &
doGet are unique to each request
Servlet/JSP
Fundamentals





Instance members vs local
variables
Major request and response
methods
More major request and response
methods
Making use of servlet context
Keeping sessions: the bane of all
Web programming
JSPs: Servlets in disguise...




Better alternative for presentation.
Insert special brackets into HTML
page to mark off Java code.
A JSP is compiled into a Servlet
the first time it is called.
Crash course in JSP syntax
JSP as presentation model
App logic
Servlet
Performs the
hard work
Helper objects
Persistent “bean” objects
DB Connections, etc
Simple calls to
bean properties
Client
request
Presentation
JSP
Unsuccessful
results
JSP
Successful
results
No servlet
need if bean
still set
Subsequent
client
request
JSP alternatives




JSP can still result in unwieldy
code creeping into HTML
Most HTML editors don’t like it
JSP:Taglibs and other “templating”
programs may help.
Much depends on how HTML
documents are produced and what
business logic you are presenting
In Depth Examples






Encapsulation of SQL calls
List results and view thread detail
Post reply and add to favorites
Set all bean properties w/ request
Edit users
Query central
Pitfalls, surprises, and
work-arounds




HTTP works via requests and
responses. Client caching of
responses poses a problem.
Guard against evil use of the
“back” button
Don’t assume everyone’s client will
respond properly to the “defaults”
Guard against easy spoofs of any
GET request which alters data.