Locale/ThemeChangeInterceptor alignment and javadoc polishing

Issue: SPR-11128
(cherry picked from commit 5e5add4)

Author: jhoeller

spring-webmvc/src/main/java/org/springframework/web/servlet/i18n/AcceptHeaderLocaleResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2013 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,14 +17,13 @@
 package org.springframework.web.servlet.i18n;
 
 import java.util.Locale;
-
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 
 import org.springframework.web.servlet.LocaleResolver;
 
 /**
- * Implementation of LocaleResolver that simply uses the primary locale
+ * {@link LocaleResolver} implementation that simply uses the primary locale
  * specified in the "accept-language" header of the HTTP request (that is,
  * the locale sent by the client browser, normally that of the client's OS).
  *

spring-webmvc/src/main/java/org/springframework/web/servlet/i18n/LocaleChangeInterceptor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2011 the original author or authors.
+ * Copyright 2002-2013 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -27,7 +27,7 @@
 
 /**
  * Interceptor that allows for changing the current locale on every request,
- * via a configurable request parameter.
+ * via a configurable request parameter (default parameter name: "locale").
  *
  * @author Juergen Hoeller
  * @since 20.06.2003

spring-webmvc/src/main/java/org/springframework/web/servlet/i18n/SessionLocaleResolver.java

@@ -24,9 +24,10 @@
 import org.springframework.web.util.WebUtils;
 
 /**
- * Implementation of LocaleResolver that uses a locale attribute in the user's
- * session in case of a custom setting, with a fallback to the specified default
- * locale or the request's accept-header locale.
+ * {@link org.springframework.web.servlet.LocaleResolver} implementation that
+ * uses a locale attribute in the user's session in case of a custom setting,
+ * with a fallback to the specified default locale or the request's
+ * accept-header locale.
  *
  * <p>This is most appropriate if the application needs user sessions anyway,
  * that is, when the HttpSession does not have to be created for the locale.

spring-webmvc/src/main/java/org/springframework/web/servlet/theme/FixedThemeResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2013 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,8 +20,9 @@
 import javax.servlet.http.HttpServletResponse;
 
 /**
- * Implementation of ThemeResolver that simply uses a fixed theme.
- * The fixed name can be defined via the "defaultThemeName" property.
+ * {@link org.springframework.web.servlet.ThemeResolver} implementation
+ * that simply uses a fixed theme. The fixed name can be defined via
+ * the "defaultThemeName" property; out of the box, it is "theme".
  *
  * <p>Note: Does not support {@code setThemeName}, as the fixed theme
  * cannot be changed.

spring-webmvc/src/main/java/org/springframework/web/servlet/theme/ThemeChangeInterceptor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2008 the original author or authors.
+ * Copyright 2002-2013 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -26,7 +26,7 @@
 
 /**
  * Interceptor that allows for changing the current theme on every request,
- * via a configurable request parameter.
+ * via a configurable request parameter (default parameter name: "theme").
  *
  * @author Juergen Hoeller
  * @since 20.06.2003
@@ -63,12 +63,12 @@ public String getParamName() {
 	public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
 			throws ServletException {
 
-		ThemeResolver themeResolver = RequestContextUtils.getThemeResolver(request);
-		if (themeResolver == null) {
-			throw new IllegalStateException("No ThemeResolver found: not in a DispatcherServlet request?");
-		}
 		String newTheme = request.getParameter(this.paramName);
 		if (newTheme != null) {
+			ThemeResolver themeResolver = RequestContextUtils.getThemeResolver(request);
+			if (themeResolver == null) {
+				throw new IllegalStateException("No ThemeResolver found: not in a DispatcherServlet request?");
+			}
 			themeResolver.setThemeName(request, response, newTheme);
 		}
 		// Proceed in any case.