Fix issue in TomcatRequestUpgradeStrategy

The method WsServerContainer.getServerContainer() was removed from
JSR-356 but remained in Tomcat a little while longer. Instead the
ServerContainer is obtained through a ServletContext attribute.
Tomcat has now removed this method, hence the need for this fix.

spring-websocket/src/main/java/org/springframework/web/socket/server/support/TomcatRequestUpgradeStrategy.java

@@ -20,6 +20,7 @@ import java.io.IOException;
 import java.lang.reflect.Method;
 import java.util.Collections;
 
+import javax.servlet.ServletContext;
 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServletRequest;
 import javax.websocket.Endpoint;
@@ -74,8 +75,9 @@ public class TomcatRequestUpgradeStrategy extends AbstractStandardUpgradeStrateg
 			throw new HandshakeFailureException("Failed to upgrade HttpServletRequest", ex);
 		}
 
-		// TODO: use ServletContext attribute when Tomcat is updated
-		WsServerContainer serverContainer = WsServerContainer.getServerContainer();
+		String attribute = "javax.websocket.server.ServerContainer";
+		ServletContext servletContext = servletRequest.getServletContext();
+		WsServerContainer serverContainer = (WsServerContainer) servletContext.getAttribute(attribute);
 
 		ServerEndpointConfig endpointConfig = new ServerEndpointRegistration("/shouldntmatter", endpoint);
 

spring-websocket/src/test/resources/log4j.xml

@@ -10,20 +10,8 @@
 		</layout>
 	</appender>
 	
-	<logger name="org.springframework.samples">
-		<level value="debug" />
-	</logger>
-	
-	<logger name="org.springframework.web">
-		<level value="debug" />
-	</logger>
-
 	<logger name="org.springframework.web.socket">
-		<level value="trace" />
-	</logger>
-
-	<logger name="org.springframework.web.stomp">
-		<level value="trace" />
+		<level value="debug" />
 	</logger>
 
 	<root>