Skip to main content

Swagger2 implementation in Spring boot

What is Swagger

Using swagger we can describe our REST APIs without much effort. We just need to do some minimal configuration and it provides a complete UI which describes all our endpoints along with interface to execute them using web browser without any additional plugin. Also it is customisable so we can add descriptions and other orchestration to our APIs.

Why Swagger

When we have a REST API and we want to share it with our users, we need to provide them all the documentation and specification for our APIs which requires some effort to prepare them. With the help of Swagger UI we can share the Swagger URL for our service where users not only see all the listed operations but they can play also with those APIs using web browser.

Implementing Swagger in Spring boot application

Now we will see how to use Swagger in our spring boot application.

Maven dependencies

Below dependencies are required for Swagger. "sringfor-swagger-ui" is required if you want Swagger to create UI for you. If you want to create your own UI then you can ignore dependencies for swagger-ui but you need springfox-swagger2 which creates REST based documentation for your API.


Swagger configuration

Now we need to create the configuration to enable the Swagger. Only this configuration can be enough if we don't want to customise the Swagger and let Swagger create the default documentation for our APIs. 
public class SwaggerConfig {
    public Docket productApi() {
        return new Docket(DocumentationType.SWAGGER_2)
                .apiInfo(new ApiInfo(
                        "Web scrapper API",
                        "Web Scrapper service for news articles",
                        new Contact("Demo user", "http://localhost:8081/about", ""),
                       "Service license 1.0",
That's it. Now you can run the application and hit the given URLs in web browser.
         This URL shows your API documentation generated by Swagger in JSON format as given below.

swagger doc resource

          Open this URL in web browser and click "Show/Hide" link. You will see the similar screen as given below.

swagger ui home page

Customizing Swagger

We can customise the swagger documentation using annotations to add more details description. For example, below code adding operations description and response types in REST endpoint.
@ApiOperation(value = "Search articles by author name")
    @ApiResponses(value = {
            @ApiResponse(code = 200, message = "Success response"),
            @ApiResponse(code = 401, message = "Resource not authorized"),
            @ApiResponse(code = 403, message = "Access forbidden"),
            @ApiResponse(code = 404, message = "Resource not found")
 @RequestMapping(value="/by-author/{authorName}", method = RequestMethod.GET, produces = "application/json")
 public List<Article> searchArticlesByAuthor(@PathVariable("authorName") String authorName) {
See the below screenshot after adding above annotations.
swagger operation execution

We can add the details to entities or domain objects also which are used in REST endpoints, like in below code we have added some meaningful description to domain model.
@ApiModel(value="Article", description="News article")
public class Article implements Serializable{
    private static final long serialVersionUID = 1L;

    @ApiModelProperty("Title for article")
    private String title;

    @ApiModelProperty("Article description")
    private String description;

    @ApiModelProperty("Author name")
    private String authorName;
See below screenshot which reflects the changes related to domain object.
swagger api details

This concludes the implementation of Swagger but Swagger is not limited to this only. We can do a more valuable things with it, like client code generation, test automation etc.


Popular Posts

Setting up kerberos in Mac OS X

Kerberos in MAC OS X Kerberos authentication allows the computers in same domain network to authenticate certain services with prompting the user for credentials. MAC OS X comes with Heimdal Kerberos which is an alternate implementation of the kerberos and uses LDAP as identity management database. Here we are going to learn how to setup a kerberos on MAC OS X which we will configure latter in our application. Installing Kerberos In MAC we can use Homebrew for installing any software package. Homebrew makes it very easy to install the kerberos by just executing a simple command as given below. brew install krb5 Once installation is complete, we need to set the below export commands in user's profile which will make the kerberos utility commands and compiler available to execute from anywhere. Open user's bash profile: vi ~/.bash_profile Add below lines: export PATH=/usr/local/opt/krb5/bin:$PATH export PATH=/usr/local/opt/krb5/sbin:$PATH export LDFLAGS=&

SpringBoot - @ConditionalOnProperty example for conditional bean initialization

@ConditionalOnProperty annotation is used to check if specified property available in the environment or it matches some specific value so it can control the execution of some part of code like bean creation. It may be useful in many cases for example enable/disable service if specific property is available. Below are the attributes which can be used for property check. havingValue - Provide the value which need to check against specified property otherwise it will check that value should not be false. matchIfMissing - If true it will match the condition and execute the annotated code when property itself is not available in environment. name - Name of the property to be tested. If you want to test single property then you can directly put the property name as string like "" and if you have multiple properties to test then you can put the names like {"prop.name1","prop.name2"} prefix - It can be use when you want to apply some prefix to

Multiple data source with Spring boot, batch and cloud task

Here we will see how we can configure different datasource for application and batch. By default, Spring batch stores the job details and execution details in database. If separate data source is not configured for spring batch then it will use the available data source in your application if configured and create batch related tables there. Which may be the unwanted burden on application database and we would like to configure separate database for spring batch. To overcome this situation we will configure the different datasource for spring batch using in-memory database, since we don't want to store batch job details permanently. Other thing is the configuration of  spring cloud task in case of multiple datasource and it must point to the same data source which is pointed by spring batch. In below sections, we will se how to configure application, batch and cloud task related data sources. Application Data Source Define the data source in application properties or yml con

Entity to DTO conversion in Java using Jackson

It's very common to have the DTO class for a given entity in any application. When persisting data, we use entity objects and when we need to provide the data to end user/application we use DTO class. Due to this we may need to have similar properties on DTO class as we have in our Entity class and to share the data we populate DTO objects using entity objects. To do this we may need to call getter on entity and then setter on DTO for the same data which increases number of code line. Also if number of DTOs are high then we need to write lot of code to just get and set the values or vice-versa. To overcome this problem we are going to use Jackson API and will see how to do it with minimal code only. Maven dependency <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>2.9.9</version> </dependency> Entity class Below is