Swagger UI integration in Spring Boot - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is Swagger UI used for in a Spring Boot project?

Swagger UI provides a visual interface to explore and test REST APIs directly from the browser, making it easier to understand and interact with the API endpoints.

beginner

Which dependency is commonly added to a Spring Boot project to enable Swagger UI?

The 'springdoc-openapi-ui' dependency is commonly used to integrate Swagger UI with Spring Boot, providing automatic API documentation and UI.

beginner

How do you access Swagger UI once integrated into a Spring Boot application?

After integration, Swagger UI is usually accessible at the URL path '/swagger-ui.html' or '/swagger-ui/index.html' in the running application.

beginner

What annotation is used to mark a Spring Boot controller to be included in Swagger documentation?

The '@RestController' annotation marks a class as a REST controller, and Swagger automatically includes its endpoints in the documentation.

intermediate

How can you customize the API information shown in Swagger UI in Spring Boot?

You can customize API info by creating a bean of type 'OpenAPI' and setting details like title, description, version, and contact information.

Which dependency should you add to a Spring Boot project to enable Swagger UI?

A org.springframework.boot:spring-boot-starter-web

B org.hibernate:hibernate-core

C org.apache.commons:commons-lang3

D org.springdoc:springdoc-openapi-ui

The 'springdoc-openapi-ui' dependency integrates Swagger UI with Spring Boot for API documentation.

What URL path typically shows the Swagger UI page in a Spring Boot app?

A /api-docs

B /swagger-ui.html

C /home

D /login

Swagger UI is usually accessible at '/swagger-ui.html' or '/swagger-ui/index.html' after integration.

Which annotation is used to define a REST controller for Swagger to document?

A @RestController

B @Component

C @Entity

D @Service

The '@RestController' annotation marks a class as a REST API controller, which Swagger documents.

How can you customize the API title and description in Swagger UI?

A By creating an OpenAPI bean with custom info

B By editing application.properties

C By changing the main class name

D By adding @CustomSwagger annotation

Creating an OpenAPI bean lets you set custom API info like title and description.

What is the main benefit of integrating Swagger UI in Spring Boot?

A Faster database queries

B Improved security

C Visual API documentation and testing

D Automatic UI themes

Swagger UI provides a visual interface to explore and test APIs easily.

Explain how to add Swagger UI to a Spring Boot project and access the API documentation.

Think about dependencies and the URL path for Swagger UI.

Describe how to customize the API information shown in Swagger UI in Spring Boot.

Customization involves creating a configuration bean.

Practice

1. What is the main purpose of integrating Swagger UI in a Spring Boot project?

easy

A. To improve database performance

B. To generate frontend UI components

C. To handle user authentication automatically

D. To provide a web page that documents and allows testing of your API

Solution

1. Step 1: Understand Swagger UI's role

   Swagger UI creates a friendly web interface to view and test API endpoints.

2. Step 2: Compare options

   Only To provide a web page that documents and allows testing of your API describes this purpose; others relate to unrelated features.

3. Final Answer:

   To provide a web page that documents and allows testing of your API -> Option D

4. Quick Check:

   Swagger UI = API documentation and testing [OK]

Hint: Swagger UI = API docs + testing page [OK]

Common Mistakes:

• Confusing Swagger UI with database tools
• Thinking Swagger handles authentication
• Assuming Swagger generates frontend code

2. Which dependency should you add to a Spring Boot project to enable Swagger UI with springdoc-openapi?

easy

A. springdoc-openapi-starter-webmvc-ui

B. spring-boot-starter-data-jpa

C. spring-boot-starter-web

D. spring-security-oauth2-client

Solution

1. Step 1: Identify the correct starter for Swagger UI

   The springdoc-openapi-starter-webmvc-ui dependency enables Swagger UI integration in Spring Boot.

2. Step 2: Eliminate unrelated dependencies

   Other options relate to web server, database, or security, not Swagger UI.

3. Final Answer:

   springdoc-openapi-starter-webmvc-ui -> Option A

4. Quick Check:

   Swagger UI dependency = springdoc-openapi-starter-webmvc-ui [OK]

Hint: Use springdoc-openapi-starter-webmvc-ui for Swagger UI [OK]

Common Mistakes:

• Adding only spring-boot-starter-web without Swagger
• Using database or security starters by mistake
• Forgetting to add any Swagger-related dependency

3. Given a Spring Boot app with springdoc-openapi-starter-webmvc-ui added, what URL should you visit to see the Swagger UI page?

medium

A. /openapi-ui/index.html

B. /api-docs/swagger-ui.html

C. /swagger-ui/index.html

D. /swagger-ui.html

Solution

1. Step 1: Recall the default Swagger UI path

   springdoc-openapi serves Swagger UI at /swagger-ui/index.html by default.

2. Step 2: Check other options

   Other URLs are incorrect or outdated paths for Swagger UI.

3. Final Answer:

   /swagger-ui/index.html -> Option C

4. Quick Check:

   Swagger UI URL = /swagger-ui/index.html [OK]

Hint: Swagger UI default path ends with /swagger-ui/index.html [OK]

Common Mistakes:

• Using /swagger-ui.html which is deprecated
• Confusing API docs JSON URL with UI URL
• Trying /openapi-ui which is invalid

4. You added springdoc-openapi-starter-webmvc-ui but visiting /swagger-ui/index.html shows 404 error. What is the most likely cause?

medium

A. You did not enable @EnableSwagger2 annotation

B. You need to restart the Spring Boot app after adding dependency

C. You forgot to add spring-boot-starter-web dependency

D. Swagger UI is only available in Spring Boot 3.x and above

Solution

1. Step 1: Check common setup issues

   After adding a new dependency, the app must be restarted to load it properly.

2. Step 2: Evaluate other options

   @EnableSwagger2 is not needed with springdoc-openapi; spring-boot-starter-web is usually present; Swagger UI works on Spring Boot 2.x too.

3. Final Answer:

   You need to restart the Spring Boot app after adding dependency -> Option B

4. Quick Check:

   Restart app after adding Swagger dependency [OK]

Hint: Restart app after adding dependencies to avoid 404 [OK]

Common Mistakes:

• Thinking @EnableSwagger2 is required with springdoc-openapi
• Missing spring-boot-starter-web (usually present)
• Assuming Swagger UI needs Spring Boot 3 only

5. You want to customize the Swagger UI page title and description in your Spring Boot app using springdoc-openapi. Which approach is correct?

hard

A. Add a bean of type OpenAPI and set info title and description

B. Edit the swagger-ui.html file directly in resources

C. Use @EnableSwagger2 annotation with title parameter

D. Set springdoc.swagger-ui.title property in application.properties

Solution

1. Step 1: Understand customization with springdoc-openapi

   Customizing title and description is done by defining an OpenAPI bean with Info details.

2. Step 2: Eliminate incorrect methods

   Editing swagger-ui.html is not recommended; @EnableSwagger2 is for older Swagger versions; springdoc.swagger-ui.title property does not exist.

3. Final Answer:

   Add a bean of type OpenAPI and set info title and description -> Option A

4. Quick Check:

   Customize Swagger UI via OpenAPI bean [OK]

Hint: Customize Swagger UI by defining OpenAPI bean [OK]

Common Mistakes:

• Trying to edit swagger-ui.html manually
• Using outdated @EnableSwagger2 annotation
• Expecting a springdoc property for title customization