Gradle – Spring 4 MVC Hello World Example – Annotation

In this tutorial, we will take the previous Gradle + Spring MVC XML example, rewrite it to support

@JavaConfig

annotation configuration, no more XML files.


Technologies used :

Gradle 2.0

Spring 4.1.6.RELEASE

Tomcat 7 or Jetty 9

Eclipse 4.4

JDK 1.7

Logback 1.1.3

Boostrap 3

1. Project Structure

Download the project source code and review the project folder structure :



P.S No more XML files like

web.xml

or Spring XML configuration files.

2. Gradle

2.1 Review the

build.gradle

file, this should be self-explanatory.

build.gradle

apply plugin: 'java'
apply plugin: 'war'
apply plugin: 'eclipse-wtp'
//apply plugin: 'jetty' //too old, Jetty 6, use gretty plugin
apply plugin: 'org.akhikhl.gretty'

// JDK 7
sourceCompatibility = 1.7
targetCompatibility = 1.7

repositories {
mavenLocal()
mavenCentral()
}

dependencies {
compile 'ch.qos.logback:logback-classic:1.1.3'
compile 'org.springframework:spring-webmvc:4.1.6.RELEASE'
compile 'javax.servlet:jstl:1.2'

//include in compile only, exclude in the war
providedCompile 'javax.servlet:servlet-api:2.5'
}

//Gretty Embedded Jetty
buildscript {
repositories {
jcenter()
}

dependencies {
classpath 'org.akhikhl.gretty:gretty:+'
}
}

// Don't use Jetty8, even it's a servlet 3.0+ container,
// but not support non-jar WebApplicationInitializer scanning.
// It will cause "No Spring WebApplicationInitializer types detected on classpath"
gretty {
port = 8080
contextPath = 'spring4'
servletContainer = 'jetty9' //tomcat7 or tomcat8
}

//For Eclipse IDE only
eclipse {

wtp {
component {

//define context path, default to project folder name
contextPath = 'spring4'

}

}
}

2.2 Make this project supports Eclipse IDE. Now, you can import the project into Eclipse IDE.

your-project$ gradle eclipse

3. Spring

@Configuration

Spring

@Configuration

and its XML equivalent.

3.1 Spring annotation configuration to scan the service classes.

SpringRootConfig.java

package com.mkyong.helloworld.config;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;

@Configuration
@ComponentScan({ "com.mkyong.helloworld.service" })
public class SpringRootConfig {
}

XML equivalent.

spring-core-config.xml

<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd ">

<context:component-scan base-package="com.mkyong.helloworld.service" />

</beans>

3.2 Extends abstract class WebMvcConfigurerAdapter.

SpringWebConfig.java

package com.mkyong.helloworld.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.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
import org.springframework.web.servlet.view.InternalResourceViewResolver;
import org.springframework.web.servlet.view.JstlView;

@EnableWebMvc //<mvc:annotation-driven />
@Configuration
@ComponentScan({ "com.mkyong.helloworld.web" })
public class SpringWebConfig extends WebMvcConfigurerAdapter {

@Override
public void addResourceHandlers(ResourceHandlerRegistry registry) {
registry.addResourceHandler("/resources/**")
.addResourceLocations("/resources/");
}

@Bean
public InternalResourceViewResolver viewResolver() {
InternalResourceViewResolver viewResolver
= new InternalResourceViewResolver();
viewResolver.setViewClass(JstlView.class);
viewResolver.setPrefix("/WEB-INF/views/jsp/");
viewResolver.setSuffix(".jsp");
return viewResolver;
}

}

XML equivalent.

spring-web-config.xml

<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd ">

<context:component-scan base-package="com.mkyong.helloworld.web" />

<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="viewClass" value="org.springframework.web.servlet.view.JstlView"/>
<property name="prefix" value="/WEB-INF/views/jsp/" />
<property name="suffix" value=".jsp" />
</bean>

<mvc:resources mapping="/resources/**" location="/resources/" />

<mvc:annotation-driven />

</beans>

4. Servlet 3.0+ Container

Create a ServletInitializer class, Servlet 3.0+ container will pick up this class and run it automatically. This is the replacement class for web.xml

package com.mkyong.helloworld.servlet3;

import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;

import com.mkyong.helloworld.config.SpringRootConfig;
import com.mkyong.helloworld.config.SpringWebConfig;

public class MyWebInitializer extends
AbstractAnnotationConfigDispatcherServletInitializer {

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

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

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

}

XML equivalent.

web.xml

<web-app xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5">

<display-name>Gradle + Spring MVC Hello World</display-name>
<description>Spring MVC web application</description>

<!-- For web context -->
<servlet>
<servlet-name>hello-dispatcher</servlet-name>
<servlet-class>
org.springframework.web.servlet.DispatcherServlet
</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/spring-mvc-config.xml</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>

<servlet-mapping>
<servlet-name>hello-dispatcher</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>

<!-- For root context -->
<listener>
<listener-class>
org.springframework.web.context.ContextLoaderListener
</listener-class>
</listener>

<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/spring-core-config.xml</param-value>
</context-param>

</web-app>

5. Demo

5.1 To run this project. Issues gradle jettyRun to start the embedded Jetty container.

Terminal

your-project$ gradle jettyRun

21:56:34 INFO  Jetty 9.2.10.v20150310 started and listening on port 8080
21:56:34 INFO  spring4 runs at:
21:56:34 INFO    http://localhost:8080/spring4 Press any key to stop the server.
> Building 87% > :jettyRun

5.2 http://localhost:8080/spring4/

5.3 http://localhost:8080/spring4/hello/mkyong.com