How can I make WebApplicationContext access beans in ApplicationContext? - spring

Question

This is how I try to bootstrap Spring in my Java Web Application:
public class SpringBootstrap implements WebApplicationInitializer {
public void onStartup(ServletContext servletContext) throws ServletException {
final AnnotationConfigApplicationContext rootContext = new AnnotationConfigApplicationContext();
rootContext.register(RootContextConfiguration.class);
final AnnotationConfigWebApplicationContext webContext = new AnnotationConfigWebApplicationContext();
webContext.register(WebContextConfiguration.class);
webContext.setParent(rootContext);
final DispatcherServlet dispatcherServlet = new DispatcherServlet(webContext);
final ServletRegistration.Dynamic dispatcher = servletContext.addServlet("springDispatcher", dispatcherServlet);
dispatcher.setLoadOnStartup(1);
dispatcher.addMapping("/");
final ContextLoaderListener contextLoadListener = new ContextLoaderListener(webContext);
servletContext.addListener(contextLoadListener);
}
}
And RootContextConfiguration and WebContextConfiguration classes are as follows:
#Configuration
#ComponentScan(basePackages = "biz.tugay.janeleven.root")
public class RootContextConfiguration {
}
#Configuration
#EnableWebMvc
#ComponentScan(basePackages = "biz.tugay.janeleven.web")
public class WebContextConfiguration {
#Bean
public ViewResolver viewResolver() {
InternalResourceViewResolver resolver = new InternalResourceViewResolver();
return resolver;
}
}
When I try deploying the application to Tomcat and start I will get:
Caused by:
org.springframework.beans.factory.NoSuchBeanDefinitionException: No
qualifying bean of type
[biz.tugay.janeleven.root.service.AppUserService] found for
dependency: expected at least 1 bean which qualifies as autowire
candidate for this dependency. Dependency annotations:
{#org.springframework.beans.factory.annotation.Autowired(required=true)}
I am also including the HelloServlet and AppUserService classes here, with their package information:
package biz.tugay.janeleven.root.service;
#Service
public class AppUserService {
public AppUser addAppUser(String name) {
final AppUser appUser = new AppUser(name);
AppUserDB.addUser(appUser);
return appUser;
}
public Collection<AppUser> getAllAppUsers() {
return AppUserDB.getAll();
}
}
package biz.tugay.janeleven.web;
#Controller
#RequestMapping(value = "/")
public class HelloWorldServlet {
#Autowired
private AppUserService appUserService;
#RequestMapping(value = "", method = RequestMethod.GET)
public String helloWorld(Model model) {
final Collection<AppUser> appUserList = appUserService.getAllAppUsers();
model.addAttribute("appUserList", appUserList);
return "hello.jsp";
}
#RequestMapping(value = "", method = RequestMethod.POST)
public String addApplicationUser(#RequestParam("username") String username) {
appUserService.addAppUser(username);
return "redirect:/";
}
}
My expectation is that, WebContextConfiguration should be able to find beans that are managed by RootContextConfiguration since I am calling:
webContext.setParent(rootContext);
during the bootstrap process. But obviously I am missing something.

Answer 1

You are correct that the web context will inherit from the root context, however
you did not include the rootContext when you initialized servletContext.addListener(); see similar code below which will help you fix your issue.
#Override
public void onStartup(ServletContext servletContext) throws ServletException {
AnnotationConfigWebApplicationContext rootContext = new AnnotationConfigWebApplicationContext();
rootContext.register(AppConfig.class);
servletContext.addListener(new ContextLoaderListener(rootContext));
AnnotationConfigWebApplicationContext dispatcherContext = new AnnotationConfigWebApplicationContext();
dispatcherContext.register(WebConfig.class);
ServletRegistration.Dynamic dispatcher = servletContext.addServlet("dispatcher",
new DispatcherServlet(dispatcherContext));
dispatcher.setLoadOnStartup(1);
dispatcher.addMapping("/");
}