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Spring FreeMarker tutorial

Spring FreeMarker tutorial shows how to use FreeMarker template engine in a Spring application.

Spring is a popular Java application framework for creating enterprise applications.

FreeMarker

FreeMarker is a server-side Java template engine for both web and standalone environments. Templates are written in the FreeMarker Template Language (FTL), which is a simple, specialized language. FreeMarker templates have .ftl extension.

Spring FreeMarker example

The following application uses FreeMarker to generate views.

pom.xml
src
├───main
│   ├───java
│   │   └───com
│   │       └───zetcode
│   │           ├───config
│   │           │       MyWebInitializer.java
│   │           │       WebConfig.java
│   │           ├───controller
│   │           │       MyController.java
│   │           └───service
│   │                   WordService.java
│   └───resources
│       │   logback.xml
│       └───templates
│               index.ftl
│               showWords.ftl
└───test
    └───java

This is the project structure.

pom.xml
<?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>

    <groupId>com.zetcode</groupId>
    <artifactId>springfreemarkerex</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>war</packaging>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>11</maven.compiler.source>
        <maven.compiler.target>11</maven.compiler.target>
    </properties>

    <dependencies>

        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-classic</artifactId>
            <version>1.2.3</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.1.3.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>4.0.1</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context-support</artifactId>
            <version>5.1.3.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>org.freemarker</groupId>
            <artifactId>freemarker</artifactId>
            <version>2.3.28</version>
        </dependency>

    </dependencies>

    <build>
        <plugins>

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-war-plugin</artifactId>
                <version>3.2.2</version>
            </plugin>

            <plugin>
                <groupId>org.eclipse.jetty</groupId>
                <artifactId>jetty-maven-plugin</artifactId>
                <version>9.4.14.v20181114</version>
            </plugin>
        </plugins>
    </build>
</project>

In the pom.xml we have the necessary dependencies.

resources/logback.xml
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <logger name="org.springframework" level="ERROR"/>
    <logger name="com.zetcode" level="INFO"/>

    <appender name="consoleAppender" class="ch.qos.logback.core.ConsoleAppender">
        <encoder>
            <Pattern>%d{HH:mm:ss.SSS} %blue(%-5level) %magenta(%logger{36}) - %msg %n
            </Pattern>
        </encoder>
    </appender>

    <root>
        <level value="INFO" />
        <appender-ref ref="consoleAppender" />
    </root>
</configuration>

The logback.xml is a configuration file for the Logback logging library.

com/zetcode/config/MyWebInitializer.java
package com.zetcode.config;

import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;

@Configuration
public class MyWebInitializer extends
        AbstractAnnotationConfigDispatcherServletInitializer {

    @Override
    protected Class<?>[] getRootConfigClasses() {
        return null;
    }

    @Override
    protected Class<?>[] getServletConfigClasses() {
        
        return new Class[]{WebConfig.class};
    }

    @Override
    protected String[] getServletMappings() {
        
        return new String[]{"/"};
    }
}

MyWebInitializer registers the Spring DispatcherServlet, which is a front controller for a Spring web application.

@Override
protected Class<?>[] getServletConfigClasses() {
    
    return new Class[]{WebConfig.class};
}

The getServletConfigClasses() returns a web configuration class.

com/zetcode/config/WebConfig.java
package com.zetcode.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
import org.springframework.web.servlet.view.freemarker.FreeMarkerConfigurer;
import org.springframework.web.servlet.view.freemarker.FreeMarkerViewResolver;

@Configuration
@EnableWebMvc
@ComponentScan(basePackages = {"com.zetcode"})
public class WebConfig implements WebMvcConfigurer {

    @Bean
    public FreeMarkerViewResolver freemarkerViewResolver() {

        var resolver = new FreeMarkerViewResolver();
        resolver.setCache(true);
        resolver.setSuffix(".ftl");
        return resolver;
    }

    @Bean
    public FreeMarkerConfigurer freemarkerConfig() {

        var freeMarkerConfigurer = new FreeMarkerConfigurer();
        freeMarkerConfigurer.setTemplateLoaderPath("classpath:/templates/");
        return freeMarkerConfigurer;
    }
}

WebConfig configures FreeMarker template engine. We set the template files location to templates directory on the classpath. (The resources is on the classpath.)

com/zetcode/service/WordService.java
package com.zetcode.service;

import org.springframework.stereotype.Service;
import java.util.List;

@Service
public class WordService {

    private final List<String> words = List.of("pen", "sky",
            "rock", "forest", "falcon", "eagle");

    public List<String> all() {

        return words;
    }
}

The WordService returns a few words.

com/zetcode/controller/MyController.java
package com.zetcode.controller;

import com.zetcode.service.WordService;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;

@Controller
public class MyController {

    @GetMapping(value = "/")
    public String home() {

        return "index";
    }

    @GetMapping(value = "/words")
    public String showWords(Model model, WordService wordService) {

        var words = wordService.all();
        model.addAttribute("words", words);

        return "showWords";
    }
}

MyController provides mappings between request paths and handler methods. We have two mappings: the home page and the showWords page.

var words = wordService.all();
model.addAttribute("words", words);

We retrieve all the words using the wordService and put it into the model. The model is passed to FreeMarker which will process the data in the template.

resources/templates/index.ftl
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Home page</title>
</head>
<body>

<p>
    <a href="words">Show words</a>
</p>

</body>
</html>

The home page contains the anchor which shows all words.

resources/templates/showWords.ftl
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Show words</title>
</head>
<body>

<h2>List of words</h2>

<ul>
<#list words as word>
    <li>${word}</li>
</#list>
</ul>

</body>
</html>

With the FreeMarker's list directive, we show all the words in an HTML list.

$ mvn jetty:run

We run the server and locate to localhost:8080 to get the home page, which has the anchor.

In this tutorial, we have worked with the FreeMarker template engine.

You might also be interested in these related tutorials: Spring @Configuration tutorial, Java tutorial, or list all Spring tutorials.