Thursday, June 26, 2014

Spring4Netty without Web.XML configuration on Java 8 (JBoss WildFly and Tomcat 8) - part.3:: Worker - Spring MVC without Web.xml usage 1


  Now we are entering the last stage in case of s4netty-worker.  Although we have already enabled Netty usage under spring ecosystem, we still want to provide some simple web (Spring MVC) for this module to see the output from the Netty JSON service.  

s4netty-worker - spring mvc output
img.1.: Spring MVC output from s4netty-worker

  I won't go into the details how to build up the basic Spring MVC project because it's easy to find out by our friend google. What is interesting is how to not use web.xml (Deployment Descriptor Element which determinates the urls mapping to appropriate servlets ) definition alias get some freedom for Java web applications. In case of s4netty-worker we do almost everything over annotations, only beans will be defined in separate app-worker-config.xml file (viz. img.2).  

img.2.: s4netty-worker module structure 

  Before we initiate web application itself by WorkerWebInitializer, that implements WebApplicationInitializerwe need to do some configuration here. (ps. WebApplicationInitializer allows us to configure servlets, filters and etc. by @Override onStatrup method)
public class WorkerWebInitializer implements WebApplicationInitializer {
   public void onStartup(ServletContext servletContext) throws ServletException {
       AnnotationConfigWebApplicationContext ctx = new AnnotationConfigWebApplicationContext();
without such configuration our WorkerWebInitializer is useless because after WebApplicationContext instantiation Spring looks for Spring configuration files annotated by @Configuration annotation. For this purpose we create WorkerWebConfig class. 

public class WorkerWebConfig {
   public UrlBasedViewResolver setupViewResolver() {

in WorkerWebConfig class we tell to the Spring where it should look for the rest of components (example: classes annotated by @Controller). By using @EnableWebMvc we import  the DelegatingWebMvcConfiguration which delegates us to all beans reliable for WebMvcConfigurer and our customisation.  At the end the method setupViewResolver allows us to briefly solve symbolic link name to the URL. Pretty cool, isn't it ?

  The one of the impact is that we can store our favorite ;) *.jsp pages in the appropriate directory (img.2.)

  Now we have ready s4netty-worker web output with appropriate Beans initialisation, which is done by ServletContext configuration definition located in the file spring/app-worker-config.xml


   And finally our result looks according to the img.1. mentioned at the beginning of this part. 
The big moment is here because we are moving to the stage 2 (s4netty-web).
The next part (Click Next

s4netty project GiTHub repository 

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