API documentation is an essential aspect of any software project, as it provides a clear understanding of how to interact with the exposed endpoints. One popular tool for generating API documentation is Java Spring REST Docs. In this blog post, we will explore how to use Java Spring REST Docs to generate API documentation in various formats.

Getting Started with Java Spring REST Docs

To get started with Java Spring REST Docs, you need to add the necessary dependencies to your project. If you are using Maven, add the following dependencies to your pom.xml file:

<dependency>
    <groupId>org.springframework.restdocs</groupId>
    <artifactId>spring-restdocs-core</artifactId>
    <version>...</version>
</dependency>
<dependency>
    <groupId>org.springframework.restdocs</groupId>
    <artifactId>spring-restdocs-mockmvc</artifactId>
    <version>...</version>
    <scope>test</scope>
</dependency>

Once you have added the dependencies, you can start generating API documentation in various formats.

Generating API Documentation in HTML Format

One of the most popular formats for API documentation is HTML. Java Spring REST Docs provides a simple way to generate API documentation in HTML format. Here is an example:

import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.restdocs.AutoConfigureRestDocs;
import org.springframework.boot.test.autoconfigure.web.servlet.AutoConfigureMockMvc;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.restdocs.mockmvc.MockMvcRestDocumentation;
import org.springframework.restdocs.payload.PayloadDocumentation;
import org.springframework.test.annotation.DirtiesContext;
import org.springframework.test.web.servlet.MockMvc;
import org.springframework.transaction.annotation.Transactional;

import static org.springframework.restdocs.mockmvc.MockMvcRestDocumentation.document;
import static org.springframework.restdocs.mockmvc.MockMvcRestDocumentation.documentationConfiguration;
import static org.springframework.restdocs.mockmvc.MockMvcRestDocumentation.snippets;

@SpringBootTest
@AutoConfigureMockMvc
@AutoConfigureRestDocs(outputDir = "target/generated-docs")
@DirtiesContext
@Transactional
class MyApiDocumentation {

    @Autowired
    private MockMvc mockMvc;

    @Test
    void generateApiDocumentation() throws Exception {
        this.mockMvc.perform(get("/api/endpoint"))
            .andExpect(status().isOk())
            .andDo(document("endpoint",
                snippets(
                    responseFields(
                        fieldWithPath("id").description("The ID of the endpoint"),
                        fieldWithPath("name").description("The name of the endpoint")
                    )
                )
            ));
    }
}

In this example, we define a test method that performs a GET request to the /api/endpoint endpoint and expects a 200 OK response. We then use the document method from MockMvcRestDocumentation to generate the documentation for this endpoint. The documentation is generated in HTML format and saved in the specified output directory (target/generated-docs in this case).

Generating API Documentation in Other Formats

Java Spring REST Docs also supports other formats for generating API documentation, such as Markdown, AsciiDoc, and PDF. To generate documentation in these formats, you need to configure the appropriate output format. Here is an example:

@AutoConfigureRestDocs(
    outputDir = "target/generated-docs",
    snippets = SnippetConfigurer.DEFAULT_SNIPPETS,
    uriScheme = "https",
    uriHost = "api.example.com"
)

In this example, we configure the output directory, default snippets, and the URI scheme and host for the API. This configuration enables Java Spring REST Docs to generate API documentation in the desired format.

Conclusion

Generating API documentation is a crucial step in any software project. Java Spring REST Docs provides a convenient way to generate API documentation in various formats, including HTML, Markdown, AsciiDoc, and PDF. By using Java Spring REST Docs, you can ensure that your API documentation is up-to-date, comprehensive, and easily accessible.

#techblog #APIdocumentation