Spring Boot first web application
Spring Boot first web application tutorial shows how to create a simple Spring Boot web application.
Spring Boot first web application
last modified July 29, 2023
Spring Boot first web application tutorial shows how to create a simple Spring Boot web application. The current trend is to launch Spring Boot applications from an executable JAR. (See SpringBootServletInitializer tutorial for an example of a traditional WAR deployment.)
Spring is a popular Java application framework. Spring Boot is an effort to create stand-alone, production-grade Spring based applications with minimal effort.
Spring Boot web application example
The application shows a message and today’s date. The message is retrieved from an appplication’s property.
build.gradle … src ├───main │ ├───java │ │ └───com │ │ └───zetcode │ │ │ Application.java │ │ └───controller │ │ MyController.java │ └───resources │ │ application.properties │ └───templates │ index.peb └───test └───java
This is the project structure.
build.gradle
plugins { id ‘org.springframework.boot’ version ‘3.1.1’ id ‘io.spring.dependency-management’ version ‘1.1.0’ id ‘java’ }
group = ‘com.zetcode’ version = ‘0.0.1-SNAPSHOT’ sourceCompatibility = ‘17’
repositories { mavenCentral() }
dependencies { implementation ‘io.pebbletemplates:pebble-spring-boot-starter:3.2.1’ implementation ‘org.springframework.boot:spring-boot-starter-web’ }
This is the Gradle build file. The spring-boot-starter-web is starter for building web, including RESTful, applications using Spring MVC.
The pebble-spring-boot-starter contains the Pebble template engine. When Spring Boot detects this starter, it automatically configures Pebble for us.
The application is packaged into a JAR file, which contains an embedded Tomcat web server.
resources/application.properties
application.message=Hello there
The application.properties file contains various configuration settings of a Spring Boot application. We have one custom message option.
com/zetcode/controller/MyController.java
package com.zetcode.controller;
import org.springframework.beans.factory.annotation.Value; import org.springframework.stereotype.Controller; import org.springframework.ui.Model; import org.springframework.web.bind.annotation.GetMapping; import java.time.LocalDate; import java.util.Map;
@Controller public class MyController {
@Value("${application.message}")
private String message = "Hi there";
@GetMapping("/")
public String index(Model model) {
model.addAttribute("now", LocalDate.now());
model.addAttribute("message", this.message);
return "index";
}
}
This is the controller class for the Spring Boot web application. A controller is decorated with the @Controller annotation. The controller has one mapping. The mapping resolves to the index.peb, which is located in the resources/templates directory.
@Value("${application.message}") private String message = “Hi there”;
We inject a value from the application.properties into the message variable.
@GetMapping("/") public String index(Model model) {
model.addAttribute("now", LocalDate.now());
model.addAttribute("message", this.message);
return "index";
}
The @GetMapping annotation maps a GET request with the / path to the index method handler. A model is created and filled with data. Spring Boot resolves the index view to the index.peb template file, to which it also sends the model data.
resources/templates/index.peb
<!DOCTYPE html> <html lang=“en”> <head> <title>Home page</title> <meta charset=“UTF-8”> <meta name=“viewport” content=“width=device-width, initial-scale=1.0”> </head> <body>
<p> Today: {{ now }} </p>
<p> Message: {{ message }} </p>
</body> </html>
The index.peb displays two values: the current date and the received message. Both values are passed to the template via the controller.
<p> Today: {{ now }} </p>
Pebble uses the {{}} syntax to display the variable.
com/zetcode/Application.java
package com.zetcode;
import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
The Application sets up the Spring Boot application.
$ ./gradlew bootRun
We run the application. Now we can navigate to localhost:8080 to see the application message.
In this article we have created our first Spring Boot web application.
Author
My name is Jan Bodnar, and I am a passionate programmer with extensive programming experience. I have been writing programming articles since 2007. To date, I have authored over 1,400 articles and 8 e-books. I possess more than ten years of experience in teaching programming.
