Spring Boot + Bootstrap + Thymeleaf Timezone Picker

1. Introduction

In this article, we are going to present the Thymeleaf Timezone Picker component. The sample application we will show in this tutorial will use a simple and very small library that fills select input with all available timezones.

For more information about Thymeleaf follow below links:
Thymeleaf Articles
Forms in Thymeleaf

2. Dependencies

2.1. Maven dependencies

The presented sample Spring Boot application is a Maven project using three common dependencies:

org.springframework.boot:spring-boot-starter-web:2.1.5.RELEASE - common Spring Boot dependency,
org.springframework.boot:spring-boot-starter-thymeleaf:2.1.5.RELEASE - Thymeleaf template engine dependency,
org.projectlombok:lombok:1.18.2 - library for generating common methods for POJO objects,
org.webjars:bootstrap:4.0.0-2 - webjar with Bootstrap framework.

2.2. Front-End libraries

bootstrap - a frontend framework for creating responsive websites.
timezones - a JavaScript library for creating select inputs and fill them with timezones.

Maven pom.xml file have the following structure:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <artifactId>thymeleaf-bootstrap-timezone-picker</artifactId>

    <properties>
        <bootstrap.version>4.0.0-2</bootstrap.version>
        <webjars-locator.version>0.30</webjars-locator.version>
        <lombok.version>1.18.2</lombok.version>
    </properties>

    <!-- Inherit defaults from Spring Boot -->
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.5.RELEASE</version>
    </parent>

    <!-- Add typical dependencies for a web application -->
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>

        <dependency>
            <groupId>org.webjars</groupId>
            <artifactId>bootstrap</artifactId>
            <version>${bootstrap.version}</version>
        </dependency>

        <dependency>
            <groupId>org.webjars</groupId>
            <artifactId>webjars-locator</artifactId>
            <version>${webjars-locator.version}</version>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>${lombok.version}</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>

    <!-- Package as an executable jar -->
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

3. Model, Controller, and Main Application class

In the model layer we have a single class Address that holds timezone field:

package com.frontbackend.thymeleaf.bootstrap.model;

import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;

@Setter
@Getter
@NoArgsConstructor
public class Settings {

    private String timezone;
}

GET and POST requests are handled by Web Controller with the following structure:

package com.frontbackend.thymeleaf.bootstrap.controller;

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;

import com.frontbackend.thymeleaf.bootstrap.model.Settings;

@Controller
@RequestMapping({ "/", "/index" })
public class IndexController {

    @GetMapping
    public String main(Model model) {
        model.addAttribute("settings", new Settings());
        return "index";
    }

    @PostMapping
    public String save(Settings settings, Model model) {
        model.addAttribute("settings", settings);
        return "saved";
    }
}

The Application is the Java class with the main method that starts the Spring Boot application server:

package com.frontbackend.thymeleaf.bootstrap;

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);
    }
}

4. Templates

In the presentation layer, we have two views:

index.html - view where we put timezone picker component,
saved.html - this view is used to present the submitted values.

The index.html template has the following structure:

<!DOCTYPE HTML>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8"/>
    <title>Spring Boot Thymeleaf Application - Bootstrap Timezone Picker</title>

    <link th:rel="stylesheet" th:href="@{/webjars/bootstrap/4.0.0-2/css/bootstrap.min.css} "/>
</head>
<body>

<!-- Navigation -->
<nav class="navbar navbar-expand-lg navbar-dark bg-dark static-top">
    <div class="container">
        <a class="navbar-brand" href="/">Thymeleaf - Bootstrap Timezone Picker</a>
        <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarResponsive"
                aria-controls="navbarResponsive"
                aria-expanded="false" aria-label="Toggle navigation">
            <span class="navbar-toggler-icon"></span>
        </button>
        <div class="collapse navbar-collapse" id="navbarResponsive">
            <ul class="navbar-nav ml-auto">
                <li class="nav-item active">
                    <a class="nav-link" href="#">Home
                        <span class="sr-only">(current)</span>
                    </a>
                </li>
                <li class="nav-item">
                    <a class="nav-link" href="#">About</a>
                </li>
                <li class="nav-item">
                    <a class="nav-link" href="#">Services</a>
                </li>
                <li class="nav-item">
                    <a class="nav-link" href="#">Contact</a>
                </li>
            </ul>
        </div>
    </div>
</nav>

<div class="container">

    <div class="row">
        <div class="col-md-4 mt-5">
            <form method="post" th:object="${settings}">

                <div class="form-group">
                    <label for="timezone">Timezone:</label>
                    <select id="timezone" placeholder="Timezone" autocomplete="off" class="form-control"
                            th:field="*{timezone}">
                    </select>
                </div>

                <button class="btn btn-primary" type="submit">Submit form</button>
            </form>
        </div>
    </div>

</div>


<script th:src="@{/webjars/jquery/jquery.min.js}"></script>
<script th:src="@{/webjars/popper.js/umd/popper.min.js}"></script>
<script th:src="@{/webjars/bootstrap/js/bootstrap.min.js}"></script>
<script th:src="@{/assets/moment/moment.min.js}"></script>
<script th:src="@{/assets/moment/moment-timezone-with-data.js}"></script>
<script th:src="@{/assets/timezones/timezones.min.js}"></script>

<script>
    $('#timezone').timezones();
</script>

</body>
</html>

To fill select box with available timezones we use simple JS library: https://github.com/firstandthird/timezones.

To initialize bootstrap-input-spinner library we use the following code:

$('#timezone').timezones();

The saved.html template has the following structure:

<!DOCTYPE HTML>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8"/>
    <title>Spring Boot Thymeleaf Application - Bootstrap Timezone Picker</title>

    <link th:rel="stylesheet" th:href="@{webjars/bootstrap/4.0.0-2/css/bootstrap.min.css} "/>
</head>
<body>

<!-- Navigation -->
<nav class="navbar navbar-expand-lg navbar-dark bg-dark static-top">
    <div class="container">
        <a class="navbar-brand" href="/">Thymeleaf - Bootstrap Timezone Picker</a>
        <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarResponsive" aria-controls="navbarResponsive"
                aria-expanded="false" aria-label="Toggle navigation">
            <span class="navbar-toggler-icon"></span>
        </button>
        <div class="collapse navbar-collapse" id="navbarResponsive">
            <ul class="navbar-nav ml-auto">
                <li class="nav-item active">
                    <a class="nav-link" href="#">Home
                        <span class="sr-only">(current)</span>
                    </a>
                </li>
                <li class="nav-item">
                    <a class="nav-link" href="#">About</a>
                </li>
                <li class="nav-item">
                    <a class="nav-link" href="#">Services</a>
                </li>
                <li class="nav-item">
                    <a class="nav-link" href="#">Contact</a>
                </li>
            </ul>
        </div>
    </div>
</nav>

<div class="container">
    <div class="row">
        <div class="col-sm-12 mt-5">
            <p><label>Timezone: </label> <strong th:text="${settings.timezone}"></strong></p>
        </div>
    </div>

    <a th:href="@{/}" class="btn btn-primary">Go back</a>
</div>

</body>
</html>

5. The output

The running application is available under http://locahost:8080 URL and presents the following functionality:

Thymeleaf bootstrap timezone picker

6. Conclusion

In this article, we presented the Thymeleaf Timezone Picker component. This picker will be definitely useful in forms where users submit their preferences and settings.

As usual, the code used in this article is available under our GitHub repository.