In computer software, a Data Access Object (DAO) is a software component which provides a common Interface (computer science) between the Application software and one or more data storage devices, such as a Database or Computer file. The term is most frequently applied to the Data Access Object Design pattern (computer science).

= Why use Data Access Objects =

Data Access Objects are considered best practice. They are a Core J2EE Design Pattern. The advantage of using data access objects is that any Business object (computer science) (which contains application or operation specific details) does not require direct knowledge of the final destination for the information it manipulates. As a result, if it is necessary to change where or how that data is stored that modification can be made without needing to change the main application.

Data Access Objects can be used in Java to insulate an application from the underlying Java persistence technology, which could be JDBC, JDO, EJB CMP, Hibernate, iBatis, or any one of a range of technologies. Using Data Access Objects means the underlying technology can be upgraded or swapped without changing other parts of the application.

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