Hooking the DAO layer

DAO is a design pattern that stands for Data Access Object. Following the separation of logic principle, DAO separates the data persistence logic in a dedicated layer and abstracts away the low-level database operations. Typically, the DAO is sketched around three main components:

• A model representing the data that is transferred between layers (for example, the Sale model corresponds to the SALE database table)
• An interface containing the API that should be implemented for the model (for example, SaleDao, or in Spring terms, SaleRepository)
• A concrete implementation of this interface (for example, SaleDaoImpl, or in Spring terms, SaleRepositoryImpl)

The following diagram represents the relationships between these components using Sale, SaleRepository, and SaleRepositoryImpl:

Figure 4.1 – DAO design pattern

If you are a JdbcTemplate fan, you most probably recognize this pattern in your own applications. On...