In this session, you will learn: 1. Design Patterns 2. Flow of the Demo App 3. Value objects 4. Data Access object 5. Factory pattern

1. Java & JEE Training
Session 35 – Design Patterns

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Agenda
• Design Patterns
• Flow of the Demo App
• Value objects
• Data Access object
• Factory pattern

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What we covered till now in Servlets…
• Servlet API – GenericServlet and HttpServlet
• Servlet LifeCycle
• Servlet Collaboration using response.sendRedirect()
• Forwarding and Including using RequestDispatcher
• Parameters and Attributes
• Session Tracking / Session Management
• Validation: Frontend & Backend.

4. The flow of the demo web apps

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Flow of the demo app
CLIENT SERVER
/index.html
Sends back index.html (HTML
Code downloaded)
/Login
Login successful HTML
+ session id
/MoreInfo with parameters +
Session ID
Page with more information
/Logout
Page with Logout Success
Message

6. Design Patterns
Value Object, DAO, Factory Pattern, Singleton

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Value Object
• Used to compound related characteristics to form a meaningful object (i.e.
object of value)
e.g. To describe currency, “1000” “USD” make sense when compounded
together to form an object
anotherMethod(amount,currency,field1,field2,field3…)
anotherMethod(money)
public class Money{
int amount;
String currency;
}

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Data Access Object
Value Object
in DAO
pattern

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STUDENT DAO EMPLOYEE DAO
DEPARTMENTS
DAO
ConnectionFactory
getConnection()
SUPPLIER OF DB CONNECTIONS

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Factory pattern

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Design Pattern Exercise
• Exercise: Create a class that can be instantiated
• Design Pattern
• JDBC Best Practices Continued

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Topics to be covered in next session
• JSP (Java Server Pages Technology)
• JSP vs Servlet
• MVC Architecture
• Scriplet

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Thank you!