Architectural patterns and domain-driven design techniques in Java

Java is one of the most widely used programming languages. It not only has object-oriented features, but also provides many powerful architectural patterns and design technologies. Among them, Domain-driven Design (DDD) is one It is a very popular technology and has a wide range of applications in actual development. This article will introduce some common Java architectural patterns and domain-driven design techniques.

1. Architectural pattern

1. MVC(Model-View-Controller)

MVC is a typical architectural pattern, which divides the system into Three parts: Model, View and Controller. The model is responsible for representing the core business logic of the application, the view is responsible for displaying data to the user, and the controller is the mediator, coordinating the interaction between the model and the view.

2. MVP(Model-View-Presenter)

MVP is similar to MVC, but there are some differences. In MVP, the model represents the application data and state, the view is responsible for displaying data to the user, and passing user input to the presenter for processing, and the role of the controller is replaced by the presenter. Presenter works similarly to a controller in MVC, but it is completely independent from the view. This is an important difference between MVP and MVC.

3. MVVM(Model-View-ViewModel)

MVVM is the abbreviation of Model-View-ViewModel. It is a variant of MVP with the purpose of better solving data binding. Determination and event handling. ViewModel is an intermediate layer that handles the interaction between the View and the Model. It also implements the data binding function and manages the state and data of the View through the ViewModel. The advantage of MVVM is that it separates UI logic and back-end logic, allowing front-end and back-end developers to focus on their respective work.

2. Domain-driven design technology

Domain-driven design (DDD) is a software development method that emphasizes integrating the core business logic of the project and its related concepts and objects , is regarded as a domain and directly reflected in the code design. DDD allows development teams to focus on solving real problems rather than getting bogged down by technology.

1. Aggregate Root

The aggregate root is the core object of the domain model. It is a collection of related objects that together represent an entity. Only aggregate roots can interact directly with the outside world. DDD implements a series of concepts on the aggregate root, such as "aggregation", "entity", etc.

2. Domain Event(Domain Event)

Domain event is a class that describes the state change of a specific domain or the specified time of the domain. Their occurrence may cause a The status of the group predefined affected objects changes. In DDD, domain events are used for communication across domains, thus maintaining the cohesion of all modules.

3. Value Object(Value Object)

Value objects are immutable objects whose equality is judged based on their internal state rather than based on their memory addresses. Value objects can refer to any domain object in the domain, but they are not entities (Entities), which means that they are not marked as unique identifiers.

Generally speaking, Domain-driven Design (DDD) starts from business needs and provides a method to focus development on core areas. Extract the aggregation and entities of the problems to be solved; establish a set of domain languages ​​and models to accurately understand and express business requirements.

Conclusion

Architectural patterns and domain-driven design techniques in Java provide developers with a wealth of solutions and tools. Using these patterns and techniques can greatly improve code quality and maintainability, and help development teams better respond to complex business scenarios and demand changes. Therefore, we should focus on learning and using these technologies in actual development to improve our development capabilities and efficiency.

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