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Today, the editor will share with you the relevant knowledge points about how to achieve the hexagonal structure of Java. The content is detailed and the logic is clear. I believe most people still know too much about this knowledge, so share this article for your reference. I hope you can get something after reading this article. Let's take a look at it.

Hexagonal architecture is a design style that separates core logic from external objects through layering. Its core logic is the business module, and the external elements are the integration points, such as database, external API, interface and so on. It divides the software into internal and external, which contains the core business logic and domain layer (the so-called hierarchical architecture), and the external includes interface, database, message passing and other content. Internal and external communicate with each other through ports and adapters.

* Note: the hexagonal architecture (Hexagonal Architecture), proposed by Alistair Cockburn, solves the problems caused by the traditional hierarchical architecture. *

1. Advantages

The software developed using hexagonal architecture is independent of channel, so it can support multi-channel.

Easy to replace inbound and outbound integration points

Testing software becomes easier because integration points can be easily simulated

2. Java implementation

As described above, the hexagonal architecture works more around ports and adapters. In Java, the port is defined with interface, and the implementation class acts as an adapter. Let's use a simple Spring Boot application example to learn how to apply the hexagonal architecture.

The main function of the sample application is to create and view employee information, the core business logic is implemented in EmployeeService, and the domain object is defined as Employee, which can be regarded as internal modules.

* * EmployeeService.java**

-- java

@ Service

Public class EmployeeService {

@ Autowired

Private EmployeeRepositoryPort employeeRepository

Public void create (String name, String role, long salary) {

EmployeeRepository.create (name, role, salary)

}

Public Employee view (Integer userId) {

Return employeeRepository.getEmployee (userId)

}

}

--

* * Employee.java**

-- java

@ Entity

@ Table (name = "employee")

Public class Employee {

@ Id

@ GeneratedValue

@ Column (name = "id")

Private Integer id

@ Column (name = "name", nullable = false)

Private String name

@ Column (name = "role", nullable = false)

Private String role

@ Column (name = "salary", nullable = false)

Private long salary

/ / Setter, Getter method

}

Now, the sample application can provide services through REST or messaging mechanisms. Create an EmployeeControllerAdapter class that implements the EmployeeUIPort interface to provide REST services.

* * EmployeeControllerAdapter.java**

-- java

RestController

@ RequestMapping ("/ employees/")

Public class EmployeeControllerAdapter implements EmployeeUIPort {

@ Autowired

Private EmployeeService employeeService

@ Override

Public void create (@ RequestBody Employee request) {

EmployeeService.create (request.getName (), request.getRole (), request.getSalary ())

}

@ Override

Public Employee view (@ PathVariable Integer id) {

Employee employee = employeeService.view (id)

Return employee

}

}

--

-- java

Public interface EmployeeUIPort {

@ PostMapping ("create")

Public void create (@ RequestBody Employee request)

@ GetMapping ("view/ {id}")

Public Employee view (@ PathVariable Integer userId)

}

As part of the business logic, EmployeeService; also needs to invoke external DB integration points. Therefore, we created the EmployeeRepositoryPort and the EmployeeServiceAdapter that implemented the interface.

* * EmployeeServiceAdapter.java**

-- java

@ Service

Public class EmployeeServiceAdapter implements EmployeeRepositoryPort {

@ PersistenceContext

Private EntityManager entityManager

@ Transactional

@ Override

Public void create (String name, String role, long salary) {

Employee employee = new Employee ()

Employee.setName (name)

Employee.setRole (role)

Employee.setSalary (salary)

EntityManager.persist (employee)

}

@ Override

Public Employee getEmployee (Integer userId) {

Return entityManager.find (Employee.class, userId)

}

}

--

* * EmployeeRepositoryPort.java**

-- java

Public interface EmployeeRepositoryPort {

Void create (String name, String role, long salary)

Employee getEmployee (Integer userId)

}

These are all the contents of the article "how to realize the hexagonal structure of Java". Thank you for reading! I believe you will gain a lot after reading this article. The editor will update different knowledge for you every day. If you want to learn more knowledge, please pay attention to the industry information channel.

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