Скачать или смотреть How to Create Multiple Instances of a Controller Bean in Spring Boot Using RequestMapping

Discover how to manage multiple instances of a controller bean in Spring Boot and efficiently route requests to different endpoints.
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Handling Multiple Instances of a Controller Bean in Spring Boot

In the world of Spring Boot, efficiently managing controller instances is essential for building robust applications. One common challenge developers face is the requirement to create multiple instances of a single controller class, each responding to different URL endpoints.

The Problem

You might find yourself in a situation where you want to handle requests to different endpoints, such as /foo and /bar, using different instances of the same controller. The objective is to manage unique states or behaviors for each endpoint without running into ambiguous mapping errors.

In a typical Spring Boot application, using @ RequestMapping on a controller method doesn’t allow for the dynamic creation of separate instances under the same class. This restriction leads to confusion and complexity in routing requests correctly.

Proposed Solution

Step-by-Step Breakdown

To efficiently create and manage multiple instances of the FooController, we will utilize Spring's prototype scope, along with dynamic registration of request mappings. Let's break this down into manageable parts:

1. Defining the Controller

First, we need to define the FooController class using the @ Controller annotation and designate it as a prototype bean. This means a new instance will be created each time Spring requires it.

[[See Video to Reveal this Text or Code Snippet]]

2. Creating the EndpointService

Next, create an EndpointService component that will handle the dynamic registration of each controller instance with their associated endpoints.

[[See Video to Reveal this Text or Code Snippet]]

3. Explanation of Key Components

Prototype Scope: This configuration allows Spring to create a new instance of FooController every time it’s requested, ensuring separate states for each instance.

Dynamic Registration: We utilize RequestMappingHandlerMapping to programmatically register request mappings. This allows us to dynamically assign different URLs to different controller instances.

Event Listener: The handleContextRefreshEvent() method listens for context refresh events, such as when the application starts up. It registers the desired mappings using our addFooController() method.

4. Testing the Results

Once you have implemented the above code, testing it is easy. Simply navigate to your endpoints:

Accessing http://localhost:8080/foo returns: Yo: foo <hashCode>

Accessing http://localhost:8080/bar returns: Yo: bar <hashCode>

Each response shows that the instances are serving different contexts and states.

Conclusion

Managing multiple instances of the same controller bean in Spring Boot doesn’t have to be a headache. By leveraging prototype scopes and dynamic request mapping registration, you can efficiently route requests and maintain unique states for your controllers.

This approach not only enhances the organization of your code but also improves the overall scalability of your Spring Boot applications. Embrace the flexibility Spring offers, and enjoy crafting cleaner, more maintainable code!