¶ title: Kotlin and Spring Boot: Building a RESTful Web Service
description:
published: true
date: 2023-02-01T08:36:43.344Z
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editor: markdown
dateCreated: 2023-02-01T08:36:39.897Z
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Kotlin 및 Spring Boot: RESTful 웹 서비스 구축Korean version of this document is available
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Kotlin 和 Spring Boot：构建 RESTful Web 服务Chinese Simplified version of this document is available
Kotlin is a modern programming language that runs on the Java Virtual Machine and can be used to build applications in a wide range of domains. Spring Boot is a framework that makes it easy to create stand-alone, production-grade Spring-based applications.
In this article, we'll see how to use Kotlin and Spring Boot to build a simple RESTful web service. We'll start by creating a Kotlin project using the Spring Initializr. Then, we'll add a few dependencies to our build file. Next, we'll write a simple controller to handle HTTP requests. Finally, we'll run our application and test our web service.
Creating a Kotlin Project
We'll start by creating a Kotlin project using the Spring Initializr. Go to the Spring Initializr website and fill in the form to create a new project. Make sure to select Kotlin as the language, and select the Web and Lombok dependencies. Lombok is a library that can be used to reduce boilerplate code.
Once you've filled in the form, click Generate Project to download a zip file containing the project. Extract the zip file and open the project in your favorite IDE.
Adding Dependencies
Next, we'll add a few dependencies to our build file. First, we'll need the Kotlin standard library. Add the following dependency to the dependencies section of your build.gradle file:
implementation("org.jetbrains.kotlin:kotlin-stdlib-jdk8")
Next, we'll add the Spring Boot Web starter. This starter will give us everything we need to build a web application with Spring Boot. Add the following dependency to the dependencies section of your build.gradle file:
implementation("org.springframework.boot:spring-boot-starter-web")
Finally, we'll add the Lombok library. This library will help us reduce boilerplate code. Add the following dependency to the dependencies section of your build.gradle file:
implementation("org.projectlombok:lombok")
Writing a Controller
Next, we'll write a simple controller to handle HTTP requests. We'll start by creating a Kotlin file called HelloController.kt in the src/main/kotlin/com/example/helloworld directory.
In this file, we'll define a controller class called HelloController. This class will have a single method called hello(). This method will take an HTTP request and return a string. Add the following code to the HelloController.kt file:
package com.example.helloworld
import org.springframework.web.bind.annotation.GetMapping
import org.springframework.web.bind.annotation.RestController
@RestController
class HelloController {
@GetMapping("/hello")
fun hello(): String {
return "Hello, World!"
}
}
In this code, we've annotated our HelloController class with the @RestController annotation. This annotation tells Spring that this class is a controller. We've also annotated our hello() method with the @GetMapping annotation. This annotation maps the hello() method to the /hello URL.
Running the Application
Now that we've written our controller, we're ready to run our application. We can do this by running the following command:
./gradlew bootRun
This command will start a web server on port 8080. We can access our web service by going to http://localhost:8080/hello in our web browser. We should see the following output:
Hello, World!
Testing the Web Service
We can also test our web service using the curl command. Run the following command to send a GET request to our web service:
curl -i http://localhost:8080/hello
This command should return the following output:
Hello, World!
Conclusion
In this article, we've seen how to use Kotlin and Spring Boot to build a simple RESTful web service. We've started by creating a Kotlin project using the Spring Initializr. Then, we've added a few dependencies to our build file. Next, we've written a simple controller to handle HTTP requests. Finally, we've run our application and tested our web service.