Polish ModelFactory

spring-web/src/main/java/org/springframework/web/method/annotation/ModelFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2014 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.
@@ -33,7 +33,6 @@ import org.springframework.validation.BindingResult;
 import org.springframework.web.HttpSessionRequiredException;
 import org.springframework.web.bind.WebDataBinder;
 import org.springframework.web.bind.annotation.ModelAttribute;
-import org.springframework.web.bind.annotation.SessionAttributes;
 import org.springframework.web.bind.support.WebDataBinderFactory;
 import org.springframework.web.context.request.NativeWebRequest;
 import org.springframework.web.method.HandlerMethod;
@@ -42,57 +41,59 @@ import org.springframework.web.method.support.ModelAndViewContainer;
 
 /**
  * Provides methods to initialize the {@link Model} before controller method
- * invocation and to update it afterwards. On initialization, the model is
- * populated with attributes from the session or by invoking
- * {@code @ModelAttribute} methods. On update, model attributes are
- * synchronized with the session -- either adding or removing them.
- * Also {@link BindingResult} attributes where missing.
+ * invocation and to update it afterwards.
+ *
+ * <p>On initialization, the model is populated with attributes from the session
+ * and by invoking methods annotated with {@code @ModelAttribute}.
+ *
+ * <p>On update, model attributes are synchronized with the session and also
+ * {@link BindingResult} attributes are added where missing.
  *
  * @author Rossen Stoyanchev
  * @since 3.1
  */
 public final class ModelFactory {
 
-	private final List<InvocableHandlerMethod> attributeMethods;
+	private final List<InvocableHandlerMethod> handlerMethods;
 
-	private final WebDataBinderFactory binderFactory;
+	private final WebDataBinderFactory dataBinderFactory;
 
 	private final SessionAttributesHandler sessionAttributesHandler;
 
+
 	/**
 	 * Create a new instance with the given {@code @ModelAttribute} methods.
-	 * @param attributeMethods for model initialization
-	 * @param binderFactory for adding {@link BindingResult} attributes
+	 * @param handlerMethods the {@code @ModelAttribute} methods to invoke
+	 * @param dataBinderFactory for preparation of {@link BindingResult} attributes
 	 * @param sessionAttributesHandler for access to session attributes
 	 */
-	public ModelFactory(List<InvocableHandlerMethod> attributeMethods,
-						WebDataBinderFactory binderFactory,
-						SessionAttributesHandler sessionAttributesHandler) {
-		this.attributeMethods = (attributeMethods != null) ? attributeMethods : new ArrayList<InvocableHandlerMethod>();
-		this.binderFactory = binderFactory;
+	public ModelFactory(List<InvocableHandlerMethod> handlerMethods, WebDataBinderFactory dataBinderFactory,
+			SessionAttributesHandler sessionAttributesHandler) {
+
+		this.handlerMethods = (handlerMethods != null) ? handlerMethods : new ArrayList<InvocableHandlerMethod>();
+		this.dataBinderFactory = dataBinderFactory;
 		this.sessionAttributesHandler = sessionAttributesHandler;
 	}
 
 	/**
 	 * Populate the model in the following order:
 	 * <ol>
-	 * 	<li>Retrieve "known" session attributes -- i.e. attributes listed via
-	 * 	{@link SessionAttributes @SessionAttributes} and previously stored in
-	 * 	the in the model at least once
-	 * 	<li>Invoke {@link ModelAttribute @ModelAttribute} methods
-	 * 	<li>Find method arguments eligible as session attributes and retrieve
-	 * 	them if they're not	already	present in the model
+	 * 	<li>Retrieve "known" session attributes listed as {@code @SessionAttributes}.
+	 * 	<li>Invoke {@code @ModelAttribute} methods
+	 * 	<li>Find {@code @ModelAttribute} method arguments also listed as
+	 * 	{@code @SessionAttributes} and ensure they're present in the model raising
+	 * 	an exception if necessary.
 	 * </ol>
 	 * @param request the current request
-	 * @param mavContainer contains the model to be initialized
+	 * @param mavContainer a container with the model to be initialized
 	 * @param handlerMethod the method for which the model is initialized
 	 * @throws Exception may arise from {@code @ModelAttribute} methods
 	 */
 	public void initModel(NativeWebRequest request, ModelAndViewContainer mavContainer, HandlerMethod handlerMethod)
 			throws Exception {
 
-		Map<String, ?> attributesInSession = this.sessionAttributesHandler.retrieveAttributes(request);
-		mavContainer.mergeAttributes(attributesInSession);
+		Map<String, ?> sessionAttributes = this.sessionAttributesHandler.retrieveAttributes(request);
+		mavContainer.mergeAttributes(sessionAttributes);
 
 		invokeModelAttributeMethods(request, mavContainer);
 
@@ -108,13 +109,13 @@ public final class ModelFactory {
 	}
 
 	/**
-	 * Invoke model attribute methods to populate the model. Attributes are
-	 * added only if not already present in the model.
+	 * Invoke model attribute methods to populate the model.
+	 * Attributes are added only if not already present in the model.
 	 */
 	private void invokeModelAttributeMethods(NativeWebRequest request, ModelAndViewContainer mavContainer)
 			throws Exception {
 
-		for (InvocableHandlerMethod attrMethod : this.attributeMethods) {
+		for (InvocableHandlerMethod attrMethod : this.handlerMethods) {
 			String modelName = attrMethod.getMethodAnnotation(ModelAttribute.class).value();
 			if (mavContainer.containsAttribute(modelName)) {
 				continue;
@@ -132,15 +133,14 @@ public final class ModelFactory {
 	}
 
 	/**
-	 * Return all {@code @ModelAttribute} arguments declared as session
-	 * attributes via {@code @SessionAttributes}.
+	 * Find {@code @ModelAttribute} arguments also listed as {@code @SessionAttributes}.
 	 */
 	private List<String> findSessionAttributeArguments(HandlerMethod handlerMethod) {
 		List<String> result = new ArrayList<String>();
-		for (MethodParameter param : handlerMethod.getMethodParameters()) {
-			if (param.hasParameterAnnotation(ModelAttribute.class)) {
-				String name = getNameForParameter(param);
-				if (this.sessionAttributesHandler.isHandlerSessionAttribute(name, param.getParameterType())) {
+		for (MethodParameter parameter : handlerMethod.getMethodParameters()) {
+			if (parameter.hasParameterAnnotation(ModelAttribute.class)) {
+				String name = getNameForParameter(parameter);
+				if (this.sessionAttributesHandler.isHandlerSessionAttribute(name, parameter.getParameterType())) {
 					result.add(name);
 				}
 			}
@@ -149,11 +149,24 @@ public final class ModelFactory {
 	}
 
 	/**
-	 * Derive the model attribute name for the given return value using
-	 * one of the following:
+	 * Derives the model attribute name for a method parameter based on:
+	 * <ol>
+	 * 	<li>The parameter {@code @ModelAttribute} annotation value
+	 * 	<li>The parameter type
+	 * </ol>
+	 * @return the derived name; never {@code null} or an empty string
+	 */
+	public static String getNameForParameter(MethodParameter parameter) {
+		ModelAttribute annot = parameter.getParameterAnnotation(ModelAttribute.class);
+		String attrName = (annot != null) ? annot.value() : null;
+		return StringUtils.hasText(attrName) ? attrName :  Conventions.getVariableNameForParameter(parameter);
+	}
+
+	/**
+	 * Derive the model attribute name for the given return value using one of:
 	 * <ol>
 	 * 	<li>The method {@code ModelAttribute} annotation value
-	 * 	<li>The declared return type if it is other than {@code Object}
+	 * 	<li>The declared return type if it is more specific than {@code Object}
 	 * 	<li>The actual return value type
 	 * </ol>
 	 * @param returnValue the value returned from a method invocation
@@ -161,9 +174,9 @@ public final class ModelFactory {
 	 * @return the model name, never {@code null} nor empty
 	 */
 	public static String getNameForReturnValue(Object returnValue, MethodParameter returnType) {
-		ModelAttribute annot = returnType.getMethodAnnotation(ModelAttribute.class);
-		if (annot != null && StringUtils.hasText(annot.value())) {
-			return annot.value();
+		ModelAttribute annotation = returnType.getMethodAnnotation(ModelAttribute.class);
+		if (annotation != null && StringUtils.hasText(annotation.value())) {
+			return annotation.value();
 		}
 		else {
 			Method method = returnType.getMethod();
@@ -173,35 +186,19 @@ public final class ModelFactory {
 	}
 
 	/**
-	 * Derives the model attribute name for a method parameter based on:
-	 * <ol>
-	 * 	<li>The parameter {@code @ModelAttribute} annotation value
-	 * 	<li>The parameter type
-	 * </ol>
-	 * @return the derived name; never {@code null} or an empty string
-	 */
-	public static String getNameForParameter(MethodParameter parameter) {
-		ModelAttribute annot = parameter.getParameterAnnotation(ModelAttribute.class);
-		String attrName = (annot != null) ? annot.value() : null;
-		return StringUtils.hasText(attrName) ? attrName :  Conventions.getVariableNameForParameter(parameter);
-	}
-
-	/**
-	 * Synchronize model attributes with the session. Add {@link BindingResult}
-	 * attributes where necessary.
+	 * Promote model attributes listed as {@code @SessionAttributes} to the session.
+	 * Add {@link BindingResult} attributes where necessary.
 	 * @param request the current request
 	 * @param mavContainer contains the model to update
 	 * @throws Exception if creating BindingResult attributes fails
 	 */
 	public void updateModel(NativeWebRequest request, ModelAndViewContainer mavContainer) throws Exception {
-
 		if (mavContainer.getSessionStatus().isComplete()){
 			this.sessionAttributesHandler.cleanupAttributes(request);
 		}
 		else {
 			this.sessionAttributesHandler.storeAttributes(request, mavContainer.getModel());
 		}
-
 		if (!mavContainer.isRequestHandled()) {
 			updateBindingResult(request, mavContainer.getModel());
 		}
@@ -219,7 +216,7 @@ public final class ModelFactory {
 				String bindingResultKey = BindingResult.MODEL_KEY_PREFIX + name;
 
 				if (!model.containsAttribute(bindingResultKey)) {
-					WebDataBinder dataBinder = binderFactory.createBinder(request, value, name);
+					WebDataBinder dataBinder = dataBinderFactory.createBinder(request, value, name);
 					model.put(bindingResultKey, dataBinder.getBindingResult());
 				}
 			}