Eliminate XML configuration using Java Based Configuration in Spring 3.2

We will required to set the home page as minimal configuration in web.xml otherwise we can remove the WEB-INF itself.

So web.xml entry:

    <welcome-file-list>

        <welcome-file>index.jsp</welcome-file>

    </welcome-file-list>

Other configurations which were in web.xml earlier are put in configuration java file:

DeploymentDescripterConfig.java:

import javax.servlet.ServletContext;

import javax.servlet.ServletException;

import javax.servlet.ServletRegistration;

import org.springframework.web.WebApplicationInitializer;

import org.springframework.web.context.ContextLoaderListener;

import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;

import org.springframework.web.context.support.GenericWebApplicationContext;

import org.springframework.web.servlet.DispatcherServlet;

public class DeploymentDescripterConfig implements WebApplicationInitializer {

        

       @Override

    public void onStartup(ServletContext servletContext) throws ServletException {

              // Create the 'root' Spring application context

           AnnotationConfigWebApplicationContext rootContext  = new AnnotationConfigWebApplicationContext();

           rootContext.scan("com.spring.package.*");

           servletContext.addListener(new ContextLoaderListener(rootContext));

          

          

           ServletRegistration.Dynamic appServlet = servletContext.addServlet("dispatcher", new DispatcherServlet(new GenericWebApplicationContext()));

           appServlet.setLoadOnStartup(1);

           appServlet.addMapping("*.htm");

          

    }

}

We also removed application-servlet.xml configuration, So its alternate java configuration file :

WebConfig.java:

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.WebMvcConfigurerAdapter;

import org.springframework.web.servlet.view.InternalResourceViewResolver;

@EnableWebMvc

@Configuration

@ComponentScan("com.spring.package.*")

public class WebConfig extends WebMvcConfigurerAdapter{

          

          

    /**

     * ViewResolver configuration required to work with resource-based views.

     */

    @Bean

    public InternalResourceViewResolver internalResourceViewResolver() {

       InternalResourceViewResolver internalResourceViewResolver = new InternalResourceViewResolver();

       internalResourceViewResolver.setPrefix("/WEB-INF/jsp/");

       internalResourceViewResolver.setSuffix(".jsp");

       internalResourceViewResolver.setOrder(0);

        return internalResourceViewResolver;

    }

}

Declaring our bean definitions:

UserConfig.java

import org.springframework.context.annotation.Bean;

import org.springframework.context.annotation.ComponentScan;

import org.springframework.context.annotation.Configuration;

import com.spring.package.domain.User;

@Configuration

@ComponentScan("com.spring.package.*")

public class UserConfig {

   

       @Bean

       public User userA() {

              User user = new User();

              user.setName("userA");

              return user;

       }

       @Bean

       public User userB() {

              User user = new User();

              user.setName("userB");

              return user;

       }

}

Create the controller:

UserListController.java :

import java.util.ArrayList;

import java.util.List;

import javax.servlet.http.HttpServletRequest;

import org.springframework.stereotype.Controller;

import org.springframework.ui.ModelMap;

import org.springframework.validation.BindingResult;

import org.springframework.web.bind.annotation.ModelAttribute;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RequestMethod;

import org.springframework.web.bind.annotation.ResponseBody;

import com.spring.package.domain.User;

@Controller

public class UserListController {

       private List<User> userList = new ArrayList<User>();

      

       @RequestMapping(value="/User.htm",method=RequestMethod.GET)

       public String showForm(ModelMap model){

              User user = new User();

              model.addAttribute("user", user);

              return "User";

       }

      

       @RequestMapping(value="/ShowUsers.htm",method=RequestMethod.POST)

       public String showUsers(ModelMap model, @ModelAttribute("user") User user, BindingResult result ){

              if(!result.hasErrors()){

                     userList.add(user);

              }else{

                     System.out.println("User has not been added to list.");;

              }

              model.addAttribute("Users", userList);

              return "ShowUsers";

       }

}

Domain User class:

public class User {

      

       private String name;

       private int age;

      

       public String getName() {

              return name;

       }

       public void setName(String name) {

              this.name = name;

       }

       public int getAge() {

              return age;

       }

       public void setAge(int age) {

              this.age = age;

       }

}

Index.jsp containing:

<jsp:forward page="/User.htm"></jsp:forward>

User.jsp containing:

<form:form method="POST" commandName="user" action="ShowUsers.htm">

       <table>

              <tr><td>Enter your name : </td><td> <form:input path="name" /><br/></td></tr>

              <tr><td>Age : </td><td> <form:input path="age" /><br/></td></tr>

              <tr><td colspan="2"><input type="submit" value="show user"></div></td></tr>

       </table>

</form:form>

showUsers.jsp containing :

<body style="color: green;">

       The following are the user is logged in :<br>

       <ul>

       <c:forEach items="${Users}" var="user">

              <li>Name : <c:out value="${user.name}" />; Age : <c:out value="${user.age}"/>

       </c:forEach>

       </ul>

</body>

And we are good to go. Bye bye xml.

We can also add test class to the above sample application:

UserConfigTest.java :

import static org.junit.Assert.assertEquals;

import static org.junit.Assert.assertNotNull;

import org.junit.Test;

import org.junit.runner.RunWith;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.beans.factory.annotation.Qualifier;

import org.springframework.test.context.ContextConfiguration;

import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

import org.springframework.test.context.web.WebAppConfiguration;

import com.spring.export.configuration.UserConfig;

import com.spring.export.domain.User;

@RunWith(SpringJUnit4ClassRunner.class)

@WebAppConfiguration // defaults to "file:src/main/webapp"

@ContextConfiguration(classes={UserConfig.class})

public class UserConfigTest{

       @Autowired

       @Qualifier("userA")

    private User user = null;

    /**

     * Tests message.

     */

    @Test

    public void testMessage() {  

        assertNotNull("Constructor message instance is null.", user);

       

        String msg = user.getName();

       

        assertNotNull("Message is null.", msg);

       

        String expectedMessage = "userA";

       

        assertEquals("Message should be '" + expectedMessage + "'.", expectedMessage, msg);

        System.out.println("message='{}'"+ msg);

    }

   

}