Thymeleaf for Java: Complete Guide with Examples

What is Thymeleaf and why is it needed?

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Thymeleaf is a modern server-side template engine for Java applications, designed for generating HTML, XML, JavaScript, CSS, and text files. Unlike JSP (JavaServer Pages), Thymeleaf offers a cleaner, more readable, and natural syntax that is easy for both developers and designers to understand.

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The main advantage of Thymeleaf is that its templates are valid HTML documents. This means you can open a template in a browser without running a server and see its structure. Dynamic data is inserted using special attributes starting with the th: prefix.

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Thymeleaf integrates perfectly with the Spring Framework (especially Spring Boot), but can also be used as a standalone library. It supports layouts, fragments, conditional constructs, loops, form handling, internationalization (i18n), and much more.

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Installing Thymeleaf

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Since Thymeleaf is a Java library, it is installed via dependency management systems like Maven or Gradle. There is no equivalent of pip install for Java.

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Installation via Maven (pom.xml)

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<dependency>\n    <groupId>org.thymeleaf</groupId>\n    <artifactId>thymeleaf</artifactId>\n    <version>3.1.2.RELEASE</version>\n</dependency>

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Installation via Gradle (build.gradle)

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implementation 'org.thymeleaf:thymeleaf:3.1.2.RELEASE'

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For Spring Boot (recommended)

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If you are using Spring Boot, simply add the starter:

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

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Spring Boot will automatically configure Thymeleaf with sensible default settings.

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Quick Start with Code Example

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Let's create a simple console application that uses Thymeleaf to generate HTML.

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Step 1: Create a template (src/main/resources/templates/hello.html)

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<!DOCTYPE html>\n<html xmlns:th="http://www.thymeleaf.org">\n<head>\n    <title>Hello Thymeleaf</title>\n</head>\n<body>\n    <h1 th:text="${message}">Default Message</h1>\n    <p>Current date: <span th:text="${#dates.format(#dates.createNow(), 'dd-MM-yyyy')}">01-01-2024</span></p>\n</body>\n</html>

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Step 2: Write Java code to process the template

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import org.thymeleaf.TemplateEngine;\nimport org.thymeleaf.context.Context;\nimport org.thymeleaf.templateresolver.ClassLoaderTemplateResolver;\n\npublic class ThymeleafQuickStart {\n    public static void main(String[] args) {\n        // 1. Configure the template resolver\n        ClassLoaderTemplateResolver resolver = new ClassLoaderTemplateResolver();\n        resolver.setPrefix("/templates/");\n        resolver.setSuffix(".html");\n        resolver.setTemplateMode("HTML");\n\n        // 2. Create the template engine\n        TemplateEngine engine = new TemplateEngine();\n        engine.setTemplateResolver(resolver);\n\n        // 3. Create a context with data\n        Context context = new Context();\n        context.setVariable("message", "Hello, Thymeleaf!");\n\n        // 4. Process the template\n        String result = engine.process("hello", context);\n        \n        System.out.println(result);\n    }\n}

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Execution result:

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<!DOCTYPE html>\n<html>\n<head>\n    <title>Hello Thymeleaf</title>\n</head>\n<body>\n    <h1>Hello, Thymeleaf!</h1>\n    <p>Current date: <span>15-03-2024</span></p>\n</body>\n</html>