Spring Jetty

last modified October 18, 2023

In this article, we show how to run Spring web application on Jetty web server.

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

Jetty

Jetty Web Server is an HTTP server and Servlet container capable of serving static and dynamic content either from a standalone or embedded instantiations.

Spring Jetty example

In the following example, we create a simple Spring web application and deploy it on the Jetty web server. For this, we use the jetty-maven-plugin.

The application displays a couple of English words.

pom.xml src ├───main │ ├───java │ │ └───com │ │ └───zetcode │ │ ├───config │ │ │ MyWebInitializer.java │ │ │ WebConfig.java │ │ └───controller │ │ MyController.java │ └───resources │ │ logback.xml │ └───templates │ index.html └───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>SpringJettyEx</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>war</packaging>

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>17</maven.compiler.source>
    <maven.compiler.target>17</maven.compiler.target>
    <spring-version>5.3.23</spring-version>
    <thymeleaf-version>3.0.15.RELEASE</thymeleaf-version>
</properties>

<dependencies>

    <dependency>
        <groupId>ch.qos.logback</groupId>
        <artifactId>logback-classic</artifactId>
        <version>1.4.0</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-webmvc</artifactId>
        <version>${spring-version}</version>
    </dependency>

    <dependency>
        <groupId>org.thymeleaf</groupId>
        <artifactId>thymeleaf-spring5</artifactId>
        <version>${thymeleaf-version}</version>
    </dependency>

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

</dependencies>

<build>
    <plugins>

        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-war-plugin</artifactId>
            <version>3.3.2</version>
        </plugin>
        <plugin>
            <groupId>org.eclipse.jetty</groupId>
            <artifactId>jetty-maven-plugin</artifactId>
            <version>9.4.49.v20220914</version>
        </plugin>
    </plugins>
</build>

</project>

In the pom.xml we have the project dependencies.

<plugin>
<groupId>org.eclipse.jetty</groupId>
<artifactId>jetty-maven-plugin</artifactId>
<version>9.4.49.v20220914</version>

</plugin>

The jetty-maven-plugin allows us to run embedded Jetty server with mvn jetty:run.

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>

This is the logback.xml configuration

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 initializes the Spring web application. It contains one configuration class: WebConfig.

com/zetcode/config/WebConfig.java

package com.zetcode.config;

import org.springframework.beans.factory.annotation.Autowired; import org.springframework.context.ApplicationContext; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.ComponentScan; import org.springframework.context.annotation.Configuration; import org.springframework.web.servlet.ViewResolver; import org.springframework.web.servlet.config.annotation.EnableWebMvc; import org.springframework.web.servlet.config.annotation.ViewResolverRegistry; import org.springframework.web.servlet.config.annotation.WebMvcConfigurer; import org.thymeleaf.spring5.SpringTemplateEngine; import org.thymeleaf.spring5.templateresolver.SpringResourceTemplateResolver; import org.thymeleaf.spring5.view.ThymeleafViewResolver;

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

@Autowired
private ApplicationContext applicationContext;

@Bean
public SpringResourceTemplateResolver templateResolver() {

    var templateResolver = new SpringResourceTemplateResolver();

    templateResolver.setApplicationContext(applicationContext);
    templateResolver.setPrefix("classpath:/templates/");
    templateResolver.setSuffix(".html");

    return templateResolver;
}

@Bean
public SpringTemplateEngine templateEngine() {

    var templateEngine = new SpringTemplateEngine();
    templateEngine.setTemplateResolver(templateResolver());
    templateEngine.setEnableSpringELCompiler(true);

    return templateEngine;
}

@Bean
public ViewResolver viewResolver() {

    var resolver = new ThymeleafViewResolver();
    var registry = new ViewResolverRegistry(null, applicationContext);

    resolver.setTemplateEngine(templateEngine());
    registry.viewResolver(resolver);

    return resolver;
}

}

The WebConfig configures the Thymeleaf template engine.

com/zetcode/controller/MyController.java

package com.zetcode.controller;

import org.springframework.http.MediaType; import org.springframework.stereotype.Controller; import org.springframework.ui.Model; import org.springframework.web.bind.annotation.GetMapping; import java.util.List;

@Controller public class MyController {

@GetMapping(value = "/", produces = MediaType.TEXT_HTML_VALUE)
public String home(Model model) {

    var words = List.of("mountain", "noon", "rock", "river", "spring");

    model.addAttribute("words", words);

    return "index";
}

}

MyController contains one route for the home page. We send some data to the template. The data will be presented in an HTML table.

resources/templates/index.html

<!DOCTYPE html> <html xmlns:th=“http://www.thymeleaf.org”> <head> <meta charset=“UTF-8”> <title>Home page</title> </head> <body>

<h2>English words</h2>

<table”> <thead> <tr> <th>Index</th> <th>Word</th> </tr> </thead> <tbody> <tr th:each=“word : ${words}"> <td th:text="${wordStat.index + 1}">Index</td> <td th:text="${word}">A word</td> </tr> </tbody> </table>

</body> </html>

This is the home page.

$ mvn jetty:run

We run the Jetty server. We navigate to the localhost:8080 to get the home page.

In this article, we have created a classic Spring web application and deployed it on embedded Jetty server.

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.

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