BAEL-82 (#4198)

* BAEL-82 revised example code

* Fix the build

* Modified example

* Clarified commented out sections of the code.

spring-all/src/main/java/com/baeldung/contexts/config/AnnotationsBasedApplicationAndServletInitializer.java

@@ -1,6 +1,5 @@
 package com.baeldung.contexts.config;
 
-import org.springframework.web.context.AbstractContextLoaderInitializer;
 import org.springframework.web.context.WebApplicationContext;
 import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
 import org.springframework.web.servlet.support.AbstractDispatcherServletInitializer;
@@ -9,20 +8,29 @@ public class AnnotationsBasedApplicationAndServletInitializer extends AbstractDi
 
     @Override
     protected WebApplicationContext createRootApplicationContext() {
-        AnnotationConfigWebApplicationContext rootContext = new AnnotationConfigWebApplicationContext();
+        //If this is not the only class declaring a root context, we return null because it would clash
-        rootContext.register(RootApplicationConfig.class);
+        //with other classes, as there can only be a single root context.
-        return rootContext;
+
+        //AnnotationConfigWebApplicationContext rootContext = new AnnotationConfigWebApplicationContext();
+        //rootContext.register(RootApplicationConfig.class);
+        //return rootContext;
+        return null;
     }
 
     @Override
     protected WebApplicationContext createServletApplicationContext() {
-        AnnotationConfigWebApplicationContext secureWebAppContext = new AnnotationConfigWebApplicationContext();
+        AnnotationConfigWebApplicationContext normalWebAppContext = new AnnotationConfigWebApplicationContext();
-        secureWebAppContext.register(SecureWebAppConfig.class);
+        normalWebAppContext.register(NormalWebAppConfig.class);
-        return secureWebAppContext;
+        return normalWebAppContext;
     }
 
     @Override
     protected String[] getServletMappings() {
-        return new String[] { "/s/api/*" };
+        return new String[] { "/api/*" };
+    }
+
+    @Override
+    protected String getServletName() {
+        return "normal-dispatcher";
     }
 }

spring-all/src/main/java/com/baeldung/contexts/config/ApplicationInitializer.java

@@ -16,7 +16,11 @@ public class ApplicationInitializer implements WebApplicationInitializer {
 
     @Override
     public void onStartup(ServletContext servletContext) throws ServletException {
-        //XML Context
+        //Here, we can define a root context and register servlets, among other things.
+        //However, since we've later defined other classes to do the same and they would clash,
+        //we leave this commented out.
+
+        //Root XML Context
         //XmlWebApplicationContext rootContext = new XmlWebApplicationContext();
         //rootContext.setConfigLocations("/WEB-INF/rootApplicationContext.xml");
         //Annotations Context
@@ -24,12 +28,13 @@ public class ApplicationInitializer implements WebApplicationInitializer {
         //rootContext.register(RootApplicationConfig.class);
         //Registration
         //servletContext.addListener(new ContextLoaderListener(rootContext));
-        
+
-        XmlWebApplicationContext normalWebAppContext = new XmlWebApplicationContext();
+        //Dispatcher Servlet
-        normalWebAppContext.setConfigLocation("/WEB-INF/normal-webapp-servlet.xml");
+        //XmlWebApplicationContext normalWebAppContext = new XmlWebApplicationContext();
-        ServletRegistration.Dynamic normal = servletContext.addServlet("normal-webapp", new DispatcherServlet(normalWebAppContext));
+        //normalWebAppContext.setConfigLocation("/WEB-INF/normal-webapp-servlet.xml");
-        normal.setLoadOnStartup(1);
+        //ServletRegistration.Dynamic normal = servletContext.addServlet("normal-webapp", new DispatcherServlet(normalWebAppContext));
-        normal.addMapping("/api/*");
+        //normal.setLoadOnStartup(1);
+        //normal.addMapping("/api/*");
     }
 
 }

spring-all/src/main/java/com/baeldung/contexts/config/SecureAnnotationsBasedApplicationAndServletInitializer.java

@@ -0,0 +1,32 @@
+package com.baeldung.contexts.config;
+
+import org.springframework.web.context.WebApplicationContext;
+import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
+import org.springframework.web.servlet.support.AbstractDispatcherServletInitializer;
+
+public class SecureAnnotationsBasedApplicationAndServletInitializer extends AbstractDispatcherServletInitializer {
+
+    @Override
+    protected WebApplicationContext createRootApplicationContext() {
+        return null;
+    }
+
+    @Override
+    protected WebApplicationContext createServletApplicationContext() {
+        AnnotationConfigWebApplicationContext secureWebAppContext = new AnnotationConfigWebApplicationContext();
+        secureWebAppContext.register(SecureWebAppConfig.class);
+        return secureWebAppContext;
+    }
+
+    @Override
+    protected String[] getServletMappings() {
+        return new String[] { "/s/api/*" };
+    }
+
+
+    @Override
+    protected String getServletName() {
+        return "secure-dispatcher";
+    }
+
+}

spring-all/src/main/java/com/baeldung/contexts/normal/HelloWorldController.java

@@ -35,7 +35,7 @@ public class HelloWorldController {
     @RequestMapping(path = "/welcome")
     public ModelAndView helloWorld() {
         processContext();
-        String message = "<br><div style='text-align:center;'>" + "<h3> " + greeterService.greet() + "</h3></div>";
+        String message = "<br><div style='text-align:center;'>" + "<h3>Normal " + greeterService.greet() + "</h3></div>";
         return new ModelAndView("welcome", "message", message);
     }
 }

spring-all/src/main/java/com/baeldung/contexts/secure/HelloWorldSecureController.java

@@ -43,7 +43,7 @@ public class HelloWorldSecureController {
     @RequestMapping(path = "/welcome")
     public ModelAndView helloWorld() {
         processContext();
-        String message = "<br><div style='text-align:center;'>" + "<h3> " + greeterService.greet() + "</h3></div>";
+        String message = "<br><div style='text-align:center;'>" + "<h3>Secure " + greeterService.greet() + "</h3></div>";
         return new ModelAndView("welcome", "message", message);
     }
 }

spring-all/src/main/java/org/baeldung/controller/config/StudentControllerConfig.java

@@ -19,10 +19,13 @@ public class StudentControllerConfig implements WebApplicationInitializer {
 
         root.setServletContext(sc);
 
-        // Manages the lifecycle of the root application context
+        //Manages the lifecycle of the root application context.
-        sc.addListener(new ContextLoaderListener(root));
+        //Conflicts with other root contexts in the application, so we've manually set the parent below.
+        //sc.addListener(new ContextLoaderListener(root));
 
-        DispatcherServlet dv = new DispatcherServlet(new GenericWebApplicationContext());
+        GenericWebApplicationContext webApplicationContext = new GenericWebApplicationContext();
+        webApplicationContext.setParent(root);
+        DispatcherServlet dv = new DispatcherServlet(webApplicationContext);
 
         ServletRegistration.Dynamic appServlet = sc.addServlet("test-mvc", dv);
         appServlet.setLoadOnStartup(1);

spring-all/src/main/java/org/baeldung/spring/config/MainWebAppInitializer.java

@@ -26,11 +26,14 @@ public class MainWebAppInitializer implements WebApplicationInitializer {
         root.scan("org.baeldung.spring.config");
         // root.getEnvironment().setDefaultProfiles("embedded");
 
-        // Manages the lifecycle of the root application context
+        //Manages the lifecycle of the root application context.
-        sc.addListener(new ContextLoaderListener(root));
+        //Conflicts with other root contexts in the application, so we've manually set the parent below.
+        //sc.addListener(new ContextLoaderListener(root));
 
         // Handles requests into the application
-        final ServletRegistration.Dynamic appServlet = sc.addServlet("mvc", new DispatcherServlet(new GenericWebApplicationContext()));
+        GenericWebApplicationContext webApplicationContext = new GenericWebApplicationContext();
+        webApplicationContext.setParent(root);
+        final ServletRegistration.Dynamic appServlet = sc.addServlet("mvc", new DispatcherServlet(webApplicationContext));
         appServlet.setLoadOnStartup(1);
         final Set<String> mappingConflicts = appServlet.addMapping("/");
         if (!mappingConflicts.isEmpty()) {

spring-all/src/main/webapp/WEB-INF/normal-webapp-servlet.xml

@@ -1,12 +1,9 @@
 <beans xmlns="http://www.springframework.org/schema/beans"
-	xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:context="http://www.springframework.org/schema/context"
+	   xmlns:context="http://www.springframework.org/schema/context"
-	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-	xsi:schemaLocation="
+	   xsi:schemaLocation="http://www.springframework.org/schema/beans
-        http://www.springframework.org/schema/beans     
         http://www.springframework.org/schema/beans/spring-beans.xsd
-        http://www.springframework.org/schema/mvc 
+        http://www.springframework.org/schema/context
-        http://www.springframework.org/schema/mvc/spring-mvc.xsd
-        http://www.springframework.org/schema/context 
         http://www.springframework.org/schema/context/spring-context.xsd">
 
 	<context:component-scan base-package="com.baeldung.contexts.normal" />

spring-all/src/main/webapp/WEB-INF/secure-webapp-servlet.xml

@@ -1,12 +1,9 @@
 <beans xmlns="http://www.springframework.org/schema/beans"
-	xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:context="http://www.springframework.org/schema/context"
+	   xmlns:context="http://www.springframework.org/schema/context"
-	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-	xsi:schemaLocation="
+	   xsi:schemaLocation="http://www.springframework.org/schema/beans
-        http://www.springframework.org/schema/beans     
         http://www.springframework.org/schema/beans/spring-beans.xsd
-        http://www.springframework.org/schema/mvc 
+        http://www.springframework.org/schema/context
-        http://www.springframework.org/schema/mvc/spring-mvc.xsd
-        http://www.springframework.org/schema/context 
         http://www.springframework.org/schema/context/spring-context.xsd">
 
 	<context:component-scan base-package="com.baeldung.contexts.secure" />

spring-all/src/main/webapp/WEB-INF/web.xml

@@ -8,8 +8,8 @@
          application initializers. -->
     <!--<absolute-ordering>
     </absolute-ordering>-->
-	
+
-	 <!-- load root application context -->
+    <!-- root application context -->
     <!--<listener>
         <listener-class>
             org.springframework.web.context.ContextLoaderListener

spring-all/src/main/webapp/WEB-INF/web_old.xml

@@ -1,41 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
-    xsi:schemaLocation="
-      http://java.sun.com/xml/ns/javaee
-      http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0"
->
-
-    <display-name>Spring MVC Application</display-name>
-
-    <!-- Spring root -->
-    <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.spring.web.config</param-value>
-    </context-param>
-
-    <listener>
-        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
-    </listener>
-
-    <!-- Spring child -->
-    <servlet>
-        <servlet-name>mvc</servlet-name>
-        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
-        <load-on-startup>1</load-on-startup>
-    </servlet>
-    <servlet-mapping>
-        <servlet-name>mvc</servlet-name>
-        <url-pattern>/</url-pattern>
-    </servlet-mapping>
-
-    <welcome-file-list>
-        <welcome-file>index.html</welcome-file>
-    </welcome-file-list>
-
-</web-app>