Implementing the data-access object pattern

To implement this pattern using the best practices of Java EE 8, we will use a relational database and implement the data read and write using a JPA specification. In this example, we will have one table named employee, which contains the employee data. We will also create a class called EmployeeDao which will have four methods –save(employee), findByName(name), findAll(), and delete(employee). The save method will receive one employee and save them on the database, findByNamewill receive the name as a parameter and will find the employee by name on the database, anddeletewill receive an employee and delete them from the database. Also, we are going to create a transfer object calledEmployee, a class that is a JPA entity and has the mapping to a database table. 

Implementing the entity with JPA

The JPA entity is a class that represents some table or view of a database. The entity needs to have an attribute that identifies only one entity, needs to...