To make our application product-ready, we need to enhance the storage of the configurations. One of the most common ways to store user credentials is to use a database to handle user information, roles, and their mappings between each other. In order to have our database configuration ready, we first need to add the spring-boot-starter-data-jpa dependency, which provides a set of convenient dependency descriptors that help us use JPA for database connectivity:

<dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-data-jpa</artifactId>
   <version>2.0.0.RELEASE</version>
</dependency>

We will use the H2 database in our example for its simplicity and its In-memory database support. You can use your favorite database instead by simply changing the Datasource configuration. Here is the Maven dependency for H2:

<dependency>
   <groupId>com.h2database</groupId>
   <artifactId>h2</artifactId>
   <version>1.4.197</version>
</dependency>

First, we need to define the JPA entities for the User and Role classes, as follows:

@Entity
@Table(name = "app_user")
public class User {
   @Id
   @GeneratedValue(strategy = GenerationType.IDENTITY)
   @Column(name = "id")
   private Long id;
 
   @Column(name = "username")
   private String username;

   @Column(name = "password")
   private String password;

   @Column(name = "name")
   private String name;
   
   @ManyToMany(fetch = FetchType.EAGER)
   @JoinTable(name = "user_role", joinColumns =
      @JoinColumn(name = "user_id",
         referencedColumnName = "id"),
         inverseJoinColumns = 
            @JoinColumn(name = "role_id",
               referencedColumnName = "id"))
    private List<Role> roles;
 
    // getters & setters
}

@Entity
@Table(name="app_role")
public class Role {
   @Id
   @GeneratedValue(strategy = GenerationType.IDENTITY)
   private Long id;

   @Column(name="role_name")
   private String roleName;
 
   // getters & setters 
}