What does dao mean in java

DAO (Data Access Object) in Java is used to separate application code and persistence layer. Its advantages include: Separation: Independent from application logic, making it easier to modify it. Encapsulation: Hide database access details and simplify interaction with the database. Scalability: Easily expandable to support new databases or persistence technologies. With DAOs, applications can call methods to perform database operations such as create, read, update, and delete entities without directly dealing with database details.

DAO in Java

Data Access Object, referred to as DAO, is a design Schemas used to separate applications from persistence layers such as databases. DAO encapsulates specific operations on the database, such as create, read, update, and delete (CRUD).

Benefits of DAO

• Separation: DAO is separated from application code, allowing independent changes to the persistence layer without impact application logic.
• Encapsulation: DAO hides database access details behind the interface, simplifying the interaction between the application and the database.
• Scalability: DAO is easily extensible to support new databases or other persistence technologies.

Implementation of DAO

DAO in Java is usually implemented in the following ways:

• Java Persistence API ( JPA): JPA provides a standard DAO layer that allows developers to define entities and database mappings using Java annotations.
• Hibernate: Hibernate is a popular ORM framework that provides a DAO layer that automatically maps Java objects to database tables.
• MyBatis: MyBatis is another popular ORM framework that allows developers to define DAO operations through XML configuration files.

Usage of DAO

When using DAO, the application only needs to call DAO methods to perform database operations. For example:

<code class="java">// 创建一个 Person 实体
Person person = new Person("John Doe");

// 使用 DAO 来保存实体
dao.save(person);

// 使用 DAO 来获取实体
Person savedPerson = dao.findById(person.getId());

// 使用 DAO 来更新实体
savedPerson.setName("Jane Doe");
dao.update(savedPerson);

// 使用 DAO 来删除实体
dao.delete(savedPerson);</code>

By using DAO, applications can interact with the database without having to deal directly with the database details. This simplifies the development process and improves application maintainability and scalability.

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