Spring Boot automated controller
last modified July 29, 2023
In this article we show how to create simple automated controller in a Spring Boot application with ViewControllerRegistry. Our application shows a simple page that displays current date. We use FreeMarker as template engine.
Spring is a popular Java application framework. Spring Boot is an effort to create stand-alone, production-grade Spring based applications without much hassle.
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.
ViewControllerRegistry
Sometimes we do not need complex controller logic and just want to return a view.
ViewControllerRegistry registers simple automated controllers
pre-configured with status code and/or a view. Its
addViewController method maps a view controller to the given URL
path (or pattern) in order to render a response with a pre-configured status
code and view.
build.gradle
...
src
├───main
│ ├───java
│ │ └───com
│ │ └───zetcode
│ │ │ Application.java
│ │ └───config
│ │ MvcConfig.java
│ └───resources
│ └───templates
│ index.ftlh
└───test
└───java
└───com
└───zetcode
HomePageTest.java
This is the project structure. FreeMarker template files have .ftlh
suffix; they are located in the resources/templates directory by
default.
plugins {
id 'java'
id 'org.springframework.boot' version '3.1.1'
id 'io.spring.dependency-management' version '1.1.0'
}
group = 'com.zetcode'
version = '0.0.1-SNAPSHOT'
java {
sourceCompatibility = '17'
}
repositories {
mavenCentral()
}
dependencies {
implementation 'org.springframework.boot:spring-boot-starter-web'
implementation 'org.springframework.boot:spring-boot-starter-freemarker'
testImplementation 'org.springframework.boot:spring-boot-starter-test'
}
test {
useJUnitPlatform()
}
The spring-boot-starter-freemarker is starter for building
Spring MVC applications with FreeMarker. The spring-boot-starter-test
imports necessary testing modules. The application is packaged into a JAR file.
package com.zetcode.config;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
@Configuration
public class MvcConfig implements WebMvcConfigurer {
@Override
public void addViewControllers(ViewControllerRegistry registry) {
registry.addViewController("/").setViewName("index");
}
}
In the MvcConfig class we configure a view and a controller for the
home page. The index view is mapped to the index.ftlh
template file which is located in the src/main/resources/templates
directory.
<#assign now = .now>
<!DOCTYPE html>
<html>
<head>
<title>Home page</title>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
</head>
<body>
<p>Today is: ${now?string.short}</p>
</body>
</html>
The index.ftlh template file is the home page of the application.
It displays current date.
<#assign now = .now>
Here we assign current date time value to the now variable.
<p>Today is: ${now?string.short}</p>
We print the date in the short format.
package com.zetcode;
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);
}
}
We set up the Spring Boot application. The @SpringBootApplication
annotation enables auto-configuration and component scanning.
package com.zetcode;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.web.servlet.MockMvc;
import org.springframework.test.web.servlet.request.MockMvcRequestBuilders;
import org.springframework.test.web.servlet.result.MockMvcResultHandlers;
import org.springframework.test.web.servlet.result.MockMvcResultMatchers;
import org.springframework.test.web.servlet.setup.MockMvcBuilders;
import org.springframework.web.context.WebApplicationContext;
@SpringBootTest
public class HomePageTest {
@Autowired
private WebApplicationContext wac;
private MockMvc mockMvc;
@BeforeEach
public void setUp() {
this.mockMvc = MockMvcBuilders.webAppContextSetup(this.wac).build();
}
@Test
public void testHomePage() throws Exception {
this.mockMvc.perform(MockMvcRequestBuilders.get("/"))
.andExpect(MockMvcResultMatchers.status().isOk())
.andExpect(MockMvcResultMatchers.view().name("index"))
.andDo(MockMvcResultHandlers.print());
}
}
This is a test for the home page.
$ ./gradlew bootRun
We start the application.
$ curl localhost:8080
<!DOCTYPE html>
<html>
<head>
<title>Home page</title>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
</head>
<body>
<p>Today is: 7/18/23, 1:47 PM</p>
</body>
</html>
With the curl tool, we retrieve the home page.
In this article we have created a simple controller and view in Spring Boot without creating a specific controller class. We have used FreeMarker as template engine.
