Swagger UI integration in Spring Boot - Step-by-Step Execution

Concept Flow - Swagger UI integration

Add Swagger dependencies

↓

Configure Swagger bean

↓

Start Spring Boot app

↓

Swagger UI available at /swagger-ui/index.html

↓

Access API docs interactively

This flow shows adding Swagger to a Spring Boot app, configuring it, running the app, and accessing the interactive API docs.

Execution Sample

Spring Boot

springdoc:
  api-docs:
    path: /v3/api-docs

@Bean
public OpenAPI customOpenAPI() {
  return new OpenAPI();
}

This code configures Springdoc OpenAPI to generate API docs and expose Swagger UI.

Execution Table

Step	Action	Result	Effect
1	Add springdoc-openapi-ui dependency	Dependency added	Enables Swagger UI support
2	Create OpenAPI bean in config	Bean registered	Customizes API docs generation
3	Run Spring Boot app	App starts	API docs generated at /v3/api-docs
4	Open browser at /swagger-ui/index.html	Swagger UI loads	Interactive API docs visible
5	Use Swagger UI to test endpoints	Requests sent	API responses shown in UI
6	Stop app	App stops	Swagger UI no longer available

💡 App stops or user closes Swagger UI, ending interaction

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	Final
springdoc-openapi-ui dependency	Not present	Added	Added	Added	Added	Added
OpenAPI bean	Not defined	Not defined	Defined	Defined	Defined	Defined
Spring Boot app state	Stopped	Stopped	Stopped	Running	Running	Stopped
Swagger UI availability	No	No	No	Yes	Yes	No

Key Moments - 3 Insights

Why do we need to add the springdoc-openapi-ui dependency first?

Because without the dependency, the Swagger UI components and API doc generation are not available, as shown in execution_table step 1.

What happens if we don't create the OpenAPI bean?

Swagger UI still works with default settings, but you cannot customize API docs. This is shown in execution_table step 2 where the bean is registered to customize.

Why can't we see Swagger UI before running the app?

Swagger UI is served by the running Spring Boot app, so until the app is running (step 3), the UI is not accessible (step 4).

Visual Quiz - 3 Questions

Look at the execution_table, at which step does the Swagger UI become accessible?

A Step 3

B Step 4

C Step 2

D Step 1

💡 Hint

Check the 'Swagger UI availability' variable in variable_tracker after each step.

According to variable_tracker, what is the state of the Spring Boot app after Step 2?

A Starting

B Running

C Stopped

D Crashed

💡 Hint

Look at the 'Spring Boot app state' row in variable_tracker after Step 2.

If we remove the OpenAPI bean configuration, what changes in the execution flow?

A API docs will use default settings

B App will fail to start

C Swagger UI will not load at all

D Swagger UI URL changes

💡 Hint

Refer to key_moments about the OpenAPI bean effect on customization.

Concept Snapshot

Swagger UI integration in Spring Boot:
1. Add springdoc-openapi-ui dependency.
2. Optionally create OpenAPI bean to customize.
3. Run app to generate API docs.
4. Access Swagger UI at /swagger-ui/index.html.
5. Use UI to explore and test APIs interactively.

Full Transcript

To integrate Swagger UI in a Spring Boot application, first add the springdoc-openapi-ui dependency to your project. Then, optionally create an OpenAPI bean to customize the API documentation. When you run the Spring Boot app, it generates API docs accessible at /v3/api-docs. You can open the Swagger UI in a browser at /swagger-ui/index.html to see interactive API documentation and test endpoints. The Swagger UI is only available while the app is running. This process helps developers and users understand and try the API easily.