Core J2EE™ Patterns: Best Practices and Design Strategies

General Refactorings

Separate Data Access Code

Data access code is embedded directly within a class that has other unrelated responsibilities.

Extract the data access code into a new class and move the new class logically and/or physically closer to the Data Source.

Figure 5.21. Separate Data Access Code

Motivation

Create cleaner abstractions, increase cohesion, and reduce coupling, thus improving modularity and reusability.

Mechanics

• Identify and extract the data access logic from the controller object.

  • Use Extract Class [Fowler] to create a new class and move data access code from the original class into the new Data Access Object (DAO) class. ...