The role of the controller layer in java

The Controller layer is a component in a Java Web application that handles user requests, executes business logic, and returns views. Its main functions include: processing HTTP requests from users. Execute business logic such as validating input, processing data, and interacting with the database. Based on the results of the business logic, select the view (e.g. HTML, JSON) to be returned to the user.

The role of the Controller layer in Java

The Controller layer is responsible for processing user requests, Components that execute business logic and return to the view layer.

Main functions:

• Processing requests: The Controller layer receives HTTP requests from users (such as GET, POST, PUT, DELETE ).
• Execute business logic: Controller is responsible for processing business logic, such as validating input, processing data, interacting with the database, etc.
• Return view: Based on the results of the business logic, the Controller selects the view to be returned to the user. Views can be in HTML, JSON, or other formats.

Structure and responsibilities:

The Controller layer usually consists of one or more controller classes, each controller is responsible for a specific functional module or a group of related ask. The controller class contains the following methods:

• Methods for processing requests: These methods are annotated with annotations (such as @GetMapping, @PostMapping) and are used to handle specific requests from users.
• Business logic methods: These methods are responsible for handling business logic, such as validating data, calling services, or querying the database.
• View resolution methods: These methods are responsible for selecting the view to be returned to the user and passing it to the view resolver.

The interaction between the Controller layer and other layers:

The interaction between the Controller layer and other layers is as follows:

• Model Layer: The Controller layer obtains the object of the Model layer through dependency injection and processes the data.
• View layer: The Controller layer passes data and view information to the View layer through the view resolver.
• Service layer: The Controller layer usually calls the Service layer's methods to handle business logic.

In short, the Controller layer plays a key role in Java web applications. It is responsible for handling user requests, executing business logic and returning views.

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