Internationalization (I18N) represents a process of designing an application for the global market. In order words, it is a process of designing an application that can be adapted to various languages and regions. In this tutorial, we will show how to implement internationalization using the Spring MVC framework.
1. Introduction
1.1 Spring Framework
- Spring is an open-source framework created to address the complexity of an enterprise application development
- One of the chief advantages of the Spring framework is its layered architecture, which allows a developer to be selective about which of its components they can use while providing a cohesive framework for
J2EEapplication development - Spring framework provides support and integration to various technologies for e.g.:
- Support for Transaction Management
- Support for interaction with the different databases
- Integration with the Object Relationship frameworks for e.g. Hibernate, iBatis etc
- Support for Dependency Injection which means all the required dependencies will be resolved with the help of containers
- Support for
RESTstyle web-services
1.2 Spring Mvc Framework
Model-View-Controller (Mvc) is a well-known design pattern for designing the GUI based applications. It mainly decouples the business logic from UI by separating the roles of Model, View, and Controller in an application. This pattern divides the application into three components to separate the internal representation of the information from the way it is being presented to the user. The three components are:
- Model (M): Model’s responsibility is to manage the application’s data, business logic, and the business rules. It is a
POJOclass which encapsulates the application data given by the controller - View (V): A view is an output representation of the information, such as displaying information or reports to the user either as a text-form or as charts. Views are usually the
JSPtemplates written with Java Standard Tag Library (JSTL) - Controller (C): Controller’s responsibility is to invoke the Models to perform the business logic and then update the view based on the model’s output. In the spring framework, the controller part is played by the Dispatcher Servlet
Now, open up the Eclipse IDE and let’s see how to achieve the internationalization for an application in the spring mvc framework!
2. Spring MVC Internationalization Example
Here is a step-by-step guide for implementing this functionality in the spring mvc framework.
2.1 Tools Used
We are using Eclipse Kepler SR2, JDK 8 and Maven. Having said that, we have tested the code against JDK 1.7 and it works well.
2.2 Project Structure
Firstly, let’s review the final project structure, in case you are confused about where you should create the corresponding files or folder later!
2.3 Project Creation
This section will demonstrate how to create a Java-based Maven project with Eclipse. In Eclipse IDE, go to File -> New -> Maven Project.
In the New Maven Project window, it will ask you to select project location. By default, ‘Use default workspace location’ will be selected. Just click on next button to proceed.
Select the Maven Web App archetype from the list of options and click next.
It will ask you to ‘Enter the group and the artifact id for the project’. We will input the details as shown in the below image. The version number will be by default: 0.0.1-SNAPSHOT.
Click on Finish and the creation of a maven project is completed. If you observe, it has downloaded the maven dependencies and a pom.xml file will be created. It will have the following code:
pom.xml
<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.spring.mvc</groupId> <artifactId>SpringMvcInternationalization</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>war</packaging> </project>
We can start adding the dependencies that developers want like Servlet API, Spring Mvc etc. Let’s start building the application!
3. Application Building
Below are the steps involved in developing this application.
3.1 Maven Dependencies
Here, we specify the dependencies for the spring mvc framework. The rest dependencies such as Spring Beans, Spring Core etc. will be automatically resolved by Maven. The updated file will have the following code:
pom.xml
<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/maven-v4_0_0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.spring.mvc</groupId> <artifactId>SpringMvcInternationalization</artifactId> <packaging>war</packaging> <version>0.0.1-SNAPSHOT</version> <name>SpringMvcInternationalization Maven Webapp</name> <url>http://maven.apache.org</url> <dependencies> <!-- Servlet API Dependency --> <dependency> <groupId>javax.servlet</groupId> <artifactId>servlet-api</artifactId> <version>3.0-alpha-1</version> </dependency> <!-- Spring Framework Dependencies --> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>5.0.6.RELEASE</version> </dependency> <!-- https://mvnrepository.com/artifact/javax.servlet/jstl --> <dependency> <groupId>javax.servlet</groupId> <artifactId>jstl</artifactId> <version>1.2</version> </dependency> </dependencies> <build> <finalName>SpringMvcIntlTest</finalName> </build> </project>
3.2 Configuration Files
Let’s write all the configuration files involved in this application.
3.2.1 Web Deployment Descriptor
The web.xml file declares one servlet (i.e. Dispatcher Servlet) to receive all kind of the requests. Dispatcher servlet here acts as a front controller. Add the following code to it:
web.xml
<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd" > <web-app> <display-name>SpringMvcInternationalizationExample</display-name> <servlet> <servlet-name>springmvcinternationaldispatcher</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>springmvcinternationaldispatcher</servlet-name> <url-pattern>/</url-pattern> </servlet-mapping> </web-app>
3.2.2 Spring Configuration File
To configure the spring framework, developers need to implement a bean configuration file i.e. springmvcinternationaldispatcher-servlet.xml which provide an interface between the basic Java class and the outside world. Add the following code to it:
springmvcinternationaldispatcher-servlet.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
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
http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd">
<!-- To activate the stereotype annotations -->
<context:component-scan base-package="com.spring.intl.controller" />
<context:annotation-config />
<!-- For reading the properties files -->
<bean id="messageSource" class="org.springframework.context.support.ReloadableResourceBundleMessageSource">
<property name="basename" value="/WEB-INF/message" />
</bean>
<!-- Locale Change Interceptor to achieve internationalization. -->
<mvc:interceptors>
<mvc:interceptor>
<mvc:mapping path="/init" />
<bean class="org.springframework.web.servlet.i18n.LocaleChangeInterceptor">
<property name="paramName" value="lang"></property>
</bean>
</mvc:interceptor>
</mvc:interceptors>
<!-- Cookie Resolver -->
<bean id="localeResolver"
class="org.springframework.web.servlet.i18n.CookieLocaleResolver">
</bean>
<!-- For resolving the view name and invoking the particular view page for
the user -->
<bean
class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/views/" />
<property name="suffix" value=".jsp"></property>
</bean>
</beans>
Do note:
- This file is loaded by the spring’s Dispatcher Servlet which receives all the requests coming into the application and dispatches them to the controller for processing
- This file has the
ReloadableResourceBundleMessageSourcebean declaration that tells the framework to enable the Internationalization (i18N) in the application. Here,- The
basenameproperty is a mandatory attribute that provides the location of the resource bundles
- The
- This file has the
LocaleChangeInterceptorbean declaration that tells that framework to intercept the incoming HTTP requests and checks for any special parameter in the requests. The parameter name that has to be searched in the incoming HTTP requests is specified by theparamNameproperty - This file has the
CookieLocaleResolverbean declaration that tells the framework to resolve the locale based on the pre-defined attribute in the cookie - This file has the
InternalResourceViewResolverbean declaration that tells the framework how to find the physicalJSPfiles according to the logical view names returned by the controllers, by attaching the prefix and the suffix to a view name
3.3 Message Resource Files
We will create two properties files which will contain all the messages to be displayed in the application. Create two files i.e. message_en.properties and message_fr.properties in the SpringMvcInternationalization/src/main/webapp/WEB-INF folder and add the following code to it:
message_en.properties
welcome.message = Hello, Daniel. Good to meet you.
message_fr.properties
welcome.message = Salut Daniel. Heureux de vous rencontrer.
3.4 Java Class Creation
Let’s create a simple class where the @Controller annotation specifies this class as a spring controller and is responsible for handling the incoming requests. Add the following code to it:
WelcomeCtrl.java
package com.spring.intl.controller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.servlet.ModelAndView;
@Controller
public class WelcomeCtrl {
@RequestMapping(value= "/init", method= RequestMethod.GET)
public ModelAndView initView() {
System.out.println("Handler method is called.");
ModelAndView modelview = new ModelAndView();
modelview.addObject("welcome_msg", "Spring Mvc Internationalization Example");
modelview.setViewName("welcome");
return modelview;
}
}
3.5 JSP View
Spring Mvc supports many types of views for different presentation technologies. These include – JSP, HTML, XML etc. So let us write a simple result view in SpringMvcInternationalization/src/main/webapp/WEB-INF/views folder.
3.5.1 Output Page
This is the output page of the example demonstrating the Internationalization in spring mvc framework. The default locale of the application will be English; however, there are two links in this page for either selecting the en or the fr locale. Add the following code to it:
welcome.jsp
<%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%>
<%@ page isELIgnored="false" %>
<%@ taglib prefix="spring" uri="http://www.springframework.org/tags" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>AdmissionPage</title>
</head>
<body>
<h2>${welcome_msg}</h2>
<hr />
<a id="en" href="/SpringMvcInternationalization/init?lang=en">English</a> | <a id="fr" href="/SpringMvcInternationalization/init?lang=fr">French</a>
<div> </div>
<div id="welcome_text">
<h4><spring:message code="welcome.message" /></h4>
</div>
</body>
</html>
4. Run the Application
As we are ready with all the changes, let us compile the project and deploy the application on the Tomcat7 server. To deploy the application on Tomat7, right-click on the project and navigate to Run as -> Run on Server.
Tomcat will deploy the application in its web-apps folder and shall start its execution to deploy the project so that we can go ahead and test it on the browser.
5. Project Demo
Open your favorite browser and hit the following URL to display the application’s output page.
http://localhost:8082/SpringMvcInternationalization/
Server name (localhost) and port (8082) may vary as per your tomcat configuration.
By default en locale is selected. Users can click on the given language links to change the application text as per their preference.
That’s all for this tutorial and I hope the article served you whatever you were looking for. Happy Learning and don’t forget to share!
6. Conclusion
In this section, developers learned how to implement internationalization in the spring mvc framework. Developers can download the sample application as an Eclipse project in the Downloads section.
7. Download the Eclipse Project
This was an example of Spring MVC Internationalization.
You can download the full source code of this example here: SpringMvcInternationalization
