What are Data Access Objects (DAOs) in Java and why are they important?

Understanding Data Access Objects (DAOs) in Java

The concept of Data Access Objects (DAOs) in Java revolves around providing an accessible interface to different data sources. Understanding DAOs requires clarity on the notion of a "data source" or "data source object."

Programmatically, a DAO is an interface or object that grants access to an underlying database or other data repositories. It serves as a mediator between the application and the persistence storage, facilitating data access and manipulation.

For instance, consider an "Employee" entity stored in an "Employee" table in a database. A DAO interface associated with the Employee entity might consist of methods for common data operations, such as:

• findAll(): Retrieves all employee records.
• findById(): Retrieves an employee by its unique identifier.
• findByName(): Retrieves employees based on their name.
• insertEmployee(Employee employee): Inserts a new employee into the database.
• updateEmployee(Employee employee): Updates an existing employee in the database.
• deleteEmployee(Employee employee): Deletes an employee from the database.

To implement these operations, separate DAO implementations would be created for different data sources, such as SQL Server or flat files. This isolates the application logic from the underlying data access mechanism, ensuring flexibility and maintainability.

The above is the detailed content of What are Data Access Objects (DAOs) in Java and why are they important?. For more information, please follow other related articles on the PHP Chinese website!