Spring Boot automated controller
Spring Boot automated controller shows how to create simple automated controller in a Spring Boot application with ViewControllerRegistry.
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.
build.gradle
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.
com/zetcode/config/MvcConfig.java
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.
resources/templates/index.ftlh
<#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.
com/zetcode/Application.java
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.
com/zetcode/HomePageTest.java
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.
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.
