Spring Boot and Kotlin Web Templates - Thymeleaf


Thymeleaf is a powerful templating engine for rendering dynamic web pages in Spring Boot applications. In this guide, we'll walk you through the steps to use Kotlin with Thymeleaf for web templates.


Setting Up Your Environment

Before you start, make sure you have Kotlin, a Java Development Kit (JDK), and an integrated development environment (IDE) like IntelliJ IDEA installed on your system. You'll also need a Spring Boot project as a starting point.


Adding Thymeleaf to Your Kotlin Project

Let's add Thymeleaf to your existing Kotlin Spring Boot project:


1. In your project, open the `build.gradle.kts` (if using Kotlin DSL) or `build.gradle` file and add the Thymeleaf dependency:

dependencies {
    // ... other dependencies
    implementation("org.springframework.boot:spring-boot-starter-thymeleaf")
}

2. Create an HTML template file using Thymeleaf syntax, for example, `index.html`:

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>Thymeleaf Example</title>
</head>
<body>
    <h1 th:text="${message}">Hello, World!</h1>
</body>
</html>

This HTML file includes Thymeleaf attributes, such as `th:text`, to bind dynamic data from the server to the HTML page.


3. Create a Kotlin controller to handle requests and set dynamic data, for example, `HelloController.kt`:

import org.springframework.stereotype.Controller
import org.springframework.ui.Model
import org.springframework.web.bind.annotation.GetMapping
@Controller
class HelloController {
    @GetMapping("/")
    fun hello(model: Model): String {
        model.addAttribute("message", "Hello, Kotlin with Thymeleaf!")
        return "index"
    }
}

This controller sets the `message` attribute in the model, which is used by the Thymeleaf template to render dynamic content.


4. Run your Spring Boot application. You can do this from your IDE or by using the command line:

./gradlew bootRun

Your Spring Boot application should be running, and when you access it, you'll see the "Hello, Kotlin with Thymeleaf!" message rendered on the HTML page.


Conclusion

Using Kotlin with Thymeleaf in Spring Boot makes it easy to create dynamic web pages. This example demonstrates the basics, but you can extend it to include more complex templates, form handling, and user interactions.


Happy coding with Kotlin and Thymeleaf!