[Spring] Context

Root WebApplicationContext 
- ContextLoaderListener에 의해 ServeletContext에 등록되는 ApplicationContext
- service layer, repository layer bean 설정  
- 공동으로 사용할 빈들을 선언. (Servlet들의 공용 영역)

Servlet WebApplicationContext 
- DispatcherServlet에 의해 생성되는 ApplicationContext. (해당 DispatcherServlet에서만 사용가능)

- Root WebApplicationContext을 상속받음
- client 요청을 받는 서블릿의 context 설정
- controller 매핑설정(handler), view resolver 처리

---

1) web.xml + xml context

 

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

<context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>/WEB-INF/*-context.xml</param-value>
</context-param>

<!-- dispatcherServlet context -->
<servlet>
    <servlet-name>normal-webapp</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>/WEB-INF/normal/*.xml</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
    <servlet-name>normal-webapp</servlet-name>
    <url-pattern>/api/*</url-pattern>
</servlet-mapping>

**  생략가능. 생략시 기본값 "dispatcher-servlet.xml"

 

2) web.xml + java context

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

<context-param>
    <param-name>contextClass</param-name>
    <param-value>
        org.springframework.web.context.support.AnnotationConfigWebApplicationContext
    </param-value>
</context-param>

<context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>org.baeldung.bean.config</param-value>
</context-param>

<servlet>
    <servlet-name>normal-webapp-annotations</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
        <param-name>contextClass</param-name>
        <param-value>org.springframework.web.context.support.AnnotationConfigWebApplicationContext</param-value>
    </init-param>
    <init-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>com.baeldung.contexts.config.NormalWebAppConfig</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>..</servlet-mapping>

** ~Config.class로 넣어도 되지만 패키지 단위로 가능하다

 

3) 3.x servlet API + xml context

public class ApplicationInitializer implements WebApplicationInitializer {
     
    @Override
    public void onStartup(ServletContext servletContext) throws ServletException {
    
        XmlWebApplicationContext rootContext = new XmlWebApplicationContext();
        rootContext.setConfigLocation("/WEB-INF/rootApplicationContext.xml");
 	servletContext.addListener(new ContextLoaderListener(rootContext));
    
    	XmlWebApplicationContext normalWebAppContext = new XmlWebApplicationContext();
	normalWebAppContext.setConfigLocation("/WEB-INF/normal-webapp-servlet.xml");

	ServletRegistration.Dynamic normal  = servletContext.addServlet("normal", new DispatcherServlet(normalWebAppContext));
	normal.setLoadOnStartup(1);
	normal.addMapping("/api/*");
    }
}

4) servelt API + java context .. (AbstractContextLoaderInitializer- Lisntener이 포함된 class)

public class AnnotationsBasedApplicationInitializer extends AbstractDispatcherServletInitializer {
  
    @Override
    protected WebApplicationContext createRootApplicationContext() {
        AnnotationConfigWebApplicationContext rootContext = new AnnotationConfigWebApplicationContext();
        rootContext.register(RootApplicationConfig.class);
        return rootContext;
    }
    
    @Override
    protected WebApplicationContext createServletApplicationContext() {

        AnnotationConfigWebApplicationContext secureWebAppContext
          = new AnnotationConfigWebApplicationContext();
        secureWebAppContext.register(SecureWebAppConfig.class);
        return secureWebAppContext;
    }

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

---

Filter

- request를 Servlert에, response를 client에 전달하기 전 작업 처리

Filter- DispatcherServlert - Filter

 

Listeners

- Context , Session 이벤트 발생시 작업 처리