Java程序辅导

COMP9321 Web Application Engineering
Semester 2, 2016
Dr. Amin Beheshti
Service Oriented Computing Group, CSE, UNSW Australia
Week 7
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http://webapps.cse.unsw.edu.au/webcms2/course/index.php?cid=2445
Design Patterns
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A pattern is a proven solution to a problem in a context.
Design Patterns
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A pattern is a proven solution to a problem in a context.
Each pattern expresses a relation between a certain context, a problem, and a solution. 
Design Patterns
4COMP9321, 16s2, Week 7
A pattern is a proven solution to a problem in a context.
Each pattern expresses a relation between a certain context, a problem, and a solution. 
A design pattern represents a solutions to problems that arise when developing a software.
Design Patterns
5COMP9321, 16s2, Week 7
A pattern is a proven solution to a problem in a context.
Each pattern expresses a relation between a certain context, a problem, and a solution. 
A design pattern represents a solutions to problems that arise when developing a software.
Design pattern are granular and applied at different levels such as:
Frameworks
Subsystems
Sub-subsystems
Design Patterns
6COMP9321, 16s2, Week 7
A pattern is a proven solution to a problem in a context.
Each pattern expresses a relation between a certain context, a problem, and a solution. 
A design pattern represents a solutions to problems that arise when developing a software.
Design pattern are granular and applied at different levels such as:
Frameworks
Subsystems
Sub-subsystems
Categories include:
Design 
Architectural 
Analysis 
Creational 
Structural 
Behavioral 
Design Patterns
7COMP9321, 16s2, Week 7
A pattern is a proven solution to a problem in a context.
Each pattern expresses a relation between a certain context, a problem, and a solution. 
A design pattern represents a solutions to problems that arise when developing a software.
Design pattern are granular and applied at different levels such as:
Frameworks
Subsystems
Sub-subsystems
Categories include:
Design 
Architectural 
Analysis 
Creational 
Structural 
Behavioral 
MVC: Model View Controllere.g.
Design Patterns
8COMP9321, 16s2, Week 7
A pattern is a proven solution to a problem in a context.
Each pattern expresses a relation between a certain context, a problem, and a solution. 
A design pattern represents a solutions to problems that arise when developing a software.
Design pattern are granular and applied at different levels such as:
Frameworks
Subsystems
Sub-subsystems
Categories include:
Design 
Architectural 
Analysis 
Creational 
Structural 
Behavioral
Gamma et al (Gang of Four) produced a famous 
book which listed 23 “Design” patterns
J2EE Design Patterns
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J2EE Design Patterns
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Web Application Architecture
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Web Application Architecture
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Web Application Architecture
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Web Application Architecture
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Web Application Architecture
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Web Application Layers
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J2EE design guidelines: Web tier
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J2EE design guidelines: Web tier
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Servlet Design Guidelines
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Servlet design guidelines: When to use Servlets
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Servlet design guidelines: When to use Servlets
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JSP Design Guidelines
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http://www.oracle.com/technetwork/articles/java/servlets-jsp-140445.html
JSP Design Guidelines
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JSP Design Guidelines
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JSP Design Guidelines
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Include directive includes the file at translation time; 
whereas the include action includes the file at runtime.
JSP Design Guidelines
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JSP Design Guidelines
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JSP Design Guidelines
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General Guideline for Servlet/JSP/JavaBeans
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General Guideline for Servlet/JSP/JavaBeans
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General Guideline for Servlet/JSP/JavaBeans
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Structuring Web applications
Architectural Patterns
(MVC)
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Structuring Web applications
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Structuring Web applications
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Structuring Web applications
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Model 1 Example
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Model 1 Example
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Model 1 Example
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Model 1 Example
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Model 1 Example
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Model 1 Example
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Model 1 Architecture
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MVC
Model View Controller
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Model 2 Architecture = MVC pattern
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Model 2 Architecture = MVC pattern
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MVC Components and Roles
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MVC can be broken down into three elements:
Model - The model represents data and the 
rules that govern access to and updates of this 
data. 
View - The view renders the contents of a 
model. It specifies exactly how the model data 
should be presented. 
Controller - The controller translates the user's 
interactions with the view into actions that the 
model will perform. 
http://www.oracle.com/technetwork/articles/javase/index-142890.html
MVC Components and Roles
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http://www.oracle.com/technetwork/articles/javase/index-142890.html
Model 2 Architecture = MVC pattern
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Model 2 Architecture = MVC pattern
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Model 2 Architecture = MVC pattern
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Model 2 Architecture = MVC pattern
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Case for a centralised controller
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Case for a centralised controller
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Case for multiple controllers
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FrontController Pattern
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FrontController Pattern
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• The Front Controller pattern is a software design pattern.
• The pattern relates to the design of web applications.
• It provides a centralized entry point for handling requests.
• Front controllers are often used in web applications to 
implement workflows.
• The front controller may be implemented as a Java object.
FrontController Pattern
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• The Front Controller pattern is a software design pattern.
• The pattern relates to the design of web applications.
• It provides a centralized entry point for handling requests.
• Front controllers are often used in web applications to 
implement workflows.
• The front controller may be implemented as a Java object.
FrontController implementation: Command Design Pattern
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Command Design Pattern
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Command Design Pattern
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Command Design Pattern
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Command Design Pattern
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Command Design Pattern
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Command Design Pattern
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Command Design Pattern
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Command Design Pattern
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Command Design Pattern
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Command Design Pattern
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Command Design Pattern
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Identifying the Command Pattern in the phonebook lab
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Implementing the Command Pattern
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Typical "Assignment 2" Architecture
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Next Week
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References
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• Core J2EE patterns, Deepak Alur, John Crupi and Dan Marlks, Prentice Hall
• Patterns of Enterprise Application Architecture, Martin Fowler, Addison-Wesley
• http://java.sun.com/blueprints/patterns/
• http://www.oracle.com/technetwork/articles/javase/index-142890.html
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