Spring Boot Hello World Example Thymeleaf
摘要: In this article, we will show you how to develop a Spring Boot web application, using Thymeleaf view, embedded Tomcat and package it as an executable JAR file.
In this article, we will show you how to develop a Spring Boot web application, using Thymeleaf view, embedded Tomcat and package it as an executable JAR file.
Technologies used :
- Spring Boot 2.1.2.RELEASE
- Spring 5.1.4.RELEASE
- Thymeleaf 3.0.11.RELEASE
- Tomcat embed 9.0.14
- JUnit 4.12
- Maven 3
- Java 8
1. Project Directory
2. Maven
Put spring-boot-starter-web and spring-boot-starter-thymeleaf, it will get anything we need to develop a Spring MVC + Thymeleaf web application, including the embedded Tomcat server.
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>
<artifactId>web-thymeleaf</artifactId>
<packaging>jar</packaging>
<name>Spring Boot Web Thymeleaf Example</name>
<description>Spring Boot Web Thymeleaf Example</description>
<version>1.0</version>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.2.RELEASE</version>
</parent>
<properties>
<java.version>1.8</java.version>
<bootstrap.version>4.2.1</bootstrap.version>
</properties>
<dependencies>
<!-- web mvc -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<!-- thymeleaf -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
<!-- test -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<!-- hot swapping, disable cache for template, enable live reload -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<optional>true</optional>
</dependency>
<!-- Optional, for bootstrap -->
<dependency>
<groupId>org.webjars</groupId>
<artifactId>bootstrap</artifactId>
<version>${bootstrap.version}</version>
</dependency>
</dependencies>
<build>
<plugins>
<!-- Package as an executable jar/war -->
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>
<addResources>true</addResources>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<version>2.22.0</version>
</plugin>
</plugins>
</build>
</project>
Display the project dependencies.
$ mvn dependency:tree [INFO] org.springframework.boot:web-thymeleaf:jar:1.0 [INFO] +- org.springframework.boot:spring-boot-starter-web:jar:2.1.2.RELEASE:compile [INFO] | +- org.springframework.boot:spring-boot-starter:jar:2.1.2.RELEASE:compile [INFO] | | +- org.springframework.boot:spring-boot-starter-logging:jar:2.1.2.RELEASE:compile [INFO] | | | +- ch.qos.logback:logback-classic:jar:1.2.3:compile [INFO] | | | | \- ch.qos.logback:logback-core:jar:1.2.3:compile [INFO] | | | +- org.apache.logging.log4j:log4j-to-slf4j:jar:2.11.1:compile [INFO] | | | | \- org.apache.logging.log4j:log4j-api:jar:2.11.1:compile [INFO] | | | \- org.slf4j:jul-to-slf4j:jar:1.7.25:compile [INFO] | | +- javax.annotation:javax.annotation-api:jar:1.3.2:compile [INFO] | | \- org.yaml:snakeyaml:jar:1.23:runtime [INFO] | +- org.springframework.boot:spring-boot-starter-json:jar:2.1.2.RELEASE:compile [INFO] | | +- com.fasterxml.jackson.core:jackson-databind:jar:2.9.8:compile [INFO] | | | +- com.fasterxml.jackson.core:jackson-annotations:jar:2.9.0:compile [INFO] | | | \- com.fasterxml.jackson.core:jackson-core:jar:2.9.8:compile [INFO] | | +- com.fasterxml.jackson.datatype:jackson-datatype-jdk8:jar:2.9.8:compile [INFO] | | +- com.fasterxml.jackson.datatype:jackson-datatype-jsr310:jar:2.9.8:compile [INFO] | | \- com.fasterxml.jackson.module:jackson-module-parameter-names:jar:2.9.8:compile [INFO] | +- org.springframework.boot:spring-boot-starter-tomcat:jar:2.1.2.RELEASE:compile [INFO] | | +- org.apache.tomcat.embed:tomcat-embed-core:jar:9.0.14:compile [INFO] | | +- org.apache.tomcat.embed:tomcat-embed-el:jar:9.0.14:compile [INFO] | | \- org.apache.tomcat.embed:tomcat-embed-websocket:jar:9.0.14:compile [INFO] | +- org.hibernate.validator:hibernate-validator:jar:6.0.14.Final:compile [INFO] | | +- javax.validation:validation-api:jar:2.0.1.Final:compile [INFO] | | +- org.jboss.logging:jboss-logging:jar:3.3.2.Final:compile [INFO] | | \- com.fasterxml:classmate:jar:1.4.0:compile [INFO] | +- org.springframework:spring-web:jar:5.1.4.RELEASE:compile [INFO] | | \- org.springframework:spring-beans:jar:5.1.4.RELEASE:compile [INFO] | \- org.springframework:spring-webmvc:jar:5.1.4.RELEASE:compile [INFO] | +- org.springframework:spring-aop:jar:5.1.4.RELEASE:compile [INFO] | +- org.springframework:spring-context:jar:5.1.4.RELEASE:compile [INFO] | \- org.springframework:spring-expression:jar:5.1.4.RELEASE:compile [INFO] +- org.springframework.boot:spring-boot-starter-thymeleaf:jar:2.1.2.RELEASE:compile [INFO] | +- org.thymeleaf:thymeleaf-spring5:jar:3.0.11.RELEASE:compile [INFO] | | +- org.thymeleaf:thymeleaf:jar:3.0.11.RELEASE:compile [INFO] | | | +- org.attoparser:attoparser:jar:2.0.5.RELEASE:compile [INFO] | | | \- org.unbescape:unbescape:jar:1.1.6.RELEASE:compile [INFO] | | \- org.slf4j:slf4j-api:jar:1.7.25:compile [INFO] | \- org.thymeleaf.extras:thymeleaf-extras-java8time:jar:3.0.2.RELEASE:compile [INFO] +- org.springframework.boot:spring-boot-starter-test:jar:2.1.2.RELEASE:test [INFO] | +- org.springframework.boot:spring-boot-test:jar:2.1.2.RELEASE:test [INFO] | +- org.springframework.boot:spring-boot-test-autoconfigure:jar:2.1.2.RELEASE:test [INFO] | +- com.jayway.jsonpath:json-path:jar:2.4.0:test [INFO] | | \- net.minidev:json-smart:jar:2.3:test [INFO] | | \- net.minidev:accessors-smart:jar:1.2:test [INFO] | | \- org.ow2.asm:asm:jar:5.0.4:test [INFO] | +- junit:junit:jar:4.12:test [INFO] | +- org.assertj:assertj-core:jar:3.11.1:test [INFO] | +- org.mockito:mockito-core:jar:2.23.4:test [INFO] | | +- net.bytebuddy:byte-buddy:jar:1.9.7:test [INFO] | | +- net.bytebuddy:byte-buddy-agent:jar:1.9.7:test [INFO] | | \- org.objenesis:objenesis:jar:2.6:test [INFO] | +- org.hamcrest:hamcrest-core:jar:1.3:test [INFO] | +- org.hamcrest:hamcrest-library:jar:1.3:test [INFO] | +- org.skyscreamer:jsonassert:jar:1.5.0:test [INFO] | | \- com.vaadin.external.google:android-json:jar:0.0.20131108.vaadin1:test [INFO] | +- org.springframework:spring-core:jar:5.1.4.RELEASE:compile [INFO] | | \- org.springframework:spring-jcl:jar:5.1.4.RELEASE:compile [INFO] | +- org.springframework:spring-test:jar:5.1.4.RELEASE:test [INFO] | \- org.xmlunit:xmlunit-core:jar:2.6.2:test [INFO] | \- javax.xml.bind:jaxb-api:jar:2.3.1:test [INFO] | \- javax.activation:javax.activation-api:jar:1.2.0:test [INFO] +- org.springframework.boot:spring-boot-devtools:jar:2.1.2.RELEASE:compile (optional) [INFO] | +- org.springframework.boot:spring-boot:jar:2.1.2.RELEASE:compile [INFO] | \- org.springframework.boot:spring-boot-autoconfigure:jar:2.1.2.RELEASE:compile [INFO] \- org.webjars:bootstrap:jar:4.2.1:compile [INFO] +- org.webjars:jquery:jar:3.0.0:compile [INFO] \- org.webjars:popper.js:jar:1.14.3:compile
3. Developer Tools
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-devtools</artifactId> <optional>true</optional> </dependency>
This spring-boot-devtools helps to disable the caches and enable hot swapping so that developers will always see the last changes. Good for development. Read this – Spring Boot – Developer tools Try to modify the Thymeleaf templates or properties files, refresh the browser to see the changes take effect immediately.
- For Eclipse IDE, it is integrated well with spring-boot-devtools.
- For Intellij IDEA, extra steps are required, read this reload static file is not working
4. Spring Boot + MVC
4.1 A simple controller.
WelcomeController.java
package com.mkyong.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 org.springframework.web.bind.annotation.RequestParam;
import java.util.Arrays;
import java.util.List;
@Controller
public class WelcomeController {
// inject via application.properties
@Value("${welcome.message}")
private String message;
private List<String> tasks = Arrays.asList("a", "b", "c", "d", "e", "f", "g");
@GetMapping("/")
public String main(Model model) {
model.addAttribute("message", message);
model.addAttribute("tasks", tasks);
return "welcome"; //view
// /hello?name=kotlin
@GetMapping("/hello")
public String mainWithParam(
@RequestParam(name = "name", required = false, defaultValue = "")
String name, Model model) {
model.addAttribute("message", name);
return "welcome"; //view
4.2 Create a class and annotate with @SpringBootApplication. In IDE, run this class to start the entire web application.
StartWebApplication.java
package com.mkyong;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class StartWebApplication {
public static void main(String[] args) {
SpringApplication.run(StartWebApplication.class, args);
5. Thymeleaf + Static files
Note
Read this Spring Boot Serving static content to understand the resource mapping.
Read this Spring Boot Serving static content to understand the resource mapping.
5.1 For Thymeleaf template files, put in src/main/resources/templates/
src/main/resources/templates/welcome.html
<!DOCTYPE HTML>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
<title>Spring Boot Thymeleaf Hello World Example</title>
<link rel="stylesheet" th:href="@{webjars/bootstrap/4.2.1/css/bootstrap.min.css}"/>
<link rel="stylesheet" th:href="@{/css/main.css}"/>
</head>
<body>
<nav class="navbar navbar-expand-md navbar-dark bg-dark fixed-top">
<a class="navbar-brand" href="#">Mkyong.com</a>
</nav>
<main role="main" class="container">
<div class="starter-template">
<h1>Spring Boot Web Thymeleaf Example</h1>
<h2>
<span th:text="'Hello, ' + ${message}"></span>
</h2>
</div>
<ol>
<li th:each="task : ${tasks}" th:text="${task}"></li>
</ol>
</main>
<!-- /.container -->
<script type="text/javascript" th:src="@{webjars/bootstrap/4.2.1/js/bootstrap.min.js}"></script>
</body>
</html>
5.2 Spring Boot common application properties
src/main/resources/application.properties
welcome.message: Mkyong spring.thymeleaf.cache=false
5.3 For Static files like CSS or JS, put in src/main/resources/static/
src/main/resources/static/css/main.css
body {
padding-top: 5rem;
.starter-template {
padding: 3rem 1.5rem;
text-align: center;
h1{
color:#0000FF;
h2{
color:#FF0000;
6. Unit Test
MockMvc to test the Spring MVC controller.
WelcomeControllerTest.java
package com.mkyong;
import com.mkyong.controller.WelcomeController;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
import org.springframework.test.context.junit4.SpringRunner;
import org.springframework.test.web.servlet.MockMvc;
import org.springframework.test.web.servlet.MvcResult;
import org.springframework.test.web.servlet.ResultActions;
import org.springframework.web.servlet.ModelAndView;
import java.util.Arrays;
import java.util.List;
import static org.hamcrest.Matchers.containsString;
import static org.hamcrest.Matchers.is;
import static org.hamcrest.core.IsEqual.equalTo;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.*;
@RunWith(SpringRunner.class)
@WebMvcTest(controllers = WelcomeController.class)
public class WelcomeControllerTest {
@Autowired
private MockMvc mockMvc;
List<String> expectedList = Arrays.asList("a", "b", "c", "d", "e", "f", "g");
@Test
public void main() throws Exception {
ResultActions resultActions = mockMvc.perform(get("/"))
.andExpect(status().isOk())
.andExpect(view().name("welcome"))
.andExpect(model().attribute("message", equalTo("Mkyong")))
.andExpect(model().attribute("tasks", is(expectedList)))
.andExpect(content().string(containsString("Hello, Mkyong")));
MvcResult mvcResult = resultActions.andReturn();
ModelAndView mv = mvcResult.getModelAndView();
//
// Get request with Param
@Test
public void hello() throws Exception {
mockMvc.perform(get("/hello").param("name", "I Love Kotlin!"))
.andExpect(status().isOk())
.andExpect(view().name("welcome"))
.andExpect(model().attribute("message", equalTo("I Love Kotlin!")))
.andExpect(content().string(containsString("Hello, I Love Kotlin!")));
7. Demo
$ mvn spring-boot:run : Tomcat initialized with port(s): 8080 (http) : Starting service [Tomcat] : Starting Servlet engine: [Apache Tomcat/9.0.14] : Tomcat started on port(s): 8080 (http) with context path '' Started StartWebApplication in 1.858 seconds (JVM running for 2.222)
URL = http://localhost:8080
URL = http://localhost:8080/hello?name=abc
8. Create an executable JAR
For deployment, just normal Maven package to create an executable JAR file.
$ mvn clean package $ java -jar target\web-thymeleaf-1.0.jar
