/*
* 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.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.web.method.annotation;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.BeanUtils;
import org.springframework.core.Conventions;
import org.springframework.core.GenericTypeResolver;
import org.springframework.core.MethodParameter;
import org.springframework.ui.Model;
import org.springframework.ui.ModelMap;
import org.springframework.util.StringUtils;
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.support.WebDataBinderFactory;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.method.support.InvocableHandlerMethod;
import org.springframework.web.method.support.ModelAndViewContainer;
/**
* Provides methods to initialize the {@link Model} before controller method
* 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 static final Log logger = LogFactory.getLog(ModelFactory.class);
private final List<ModelMethod> modelMethods = new ArrayList<ModelMethod>();
private final WebDataBinderFactory dataBinderFactory;
private final SessionAttributesHandler sessionAttributesHandler;
/**
* Create a new instance with the given {@code @ModelAttribute} methods.
* @param invocableMethods 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> invocableMethods, WebDataBinderFactory dataBinderFactory,
SessionAttributesHandler sessionAttributesHandler) {
if (invocableMethods != null) {
for (InvocableHandlerMethod method : invocableMethods) {
this.modelMethods.add(new ModelMethod(method));
}
}
this.dataBinderFactory = dataBinderFactory;
this.sessionAttributesHandler = sessionAttributesHandler;
}
/**
* Populate the model in the following order:
* <ol>
* <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 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, ?> sessionAttributes = this.sessionAttributesHandler.retrieveAttributes(request);
mavContainer.mergeAttributes(sessionAttributes);
invokeModelAttributeMethods(request, mavContainer);
for (String name : findSessionAttributeArguments(handlerMethod)) {
if (!mavContainer.containsAttribute(name)) {
Object value = this.sessionAttributesHandler.retrieveAttribute(request, name);
if (value == null) {
throw new HttpSessionRequiredException("Expected session attribute '" + name + "'");
}
mavContainer.addAttribute(name, value);
}
}
}
/**
* 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 {
while (!this.modelMethods.isEmpty()) {
InvocableHandlerMethod attrMethod = getNextModelMethod(mavContainer).getHandlerMethod();
String modelName = attrMethod.getMethodAnnotation(ModelAttribute.class).value();
if (mavContainer.containsAttribute(modelName)) {
continue;
}
Object returnValue = attrMethod.invokeForRequest(request, mavContainer);
if (!attrMethod.isVoid()){
String returnValueName = getNameForReturnValue(returnValue, attrMethod.getReturnType());
if (!mavContainer.containsAttribute(returnValueName)) {
mavContainer.addAttribute(returnValueName, returnValue);
}
}
}
}
private ModelMethod getNextModelMethod(ModelAndViewContainer mavContainer) {
for (ModelMethod modelMethod : this.modelMethods) {
if (modelMethod.checkDependencies(mavContainer)) {
if (logger.isTraceEnabled()) {
logger.trace("Selected @ModelAttribute method " + modelMethod);
}
this.modelMethods.remove(modelMethod);
return modelMethod;
}
}
ModelMethod modelMethod = this.modelMethods.get(0);
if (logger.isTraceEnabled()) {
logger.trace("Selected @ModelAttribute method (not present: " +
modelMethod.getUnresolvedDependencies(mavContainer)+ ") " + modelMethod);
}
this.modelMethods.remove(modelMethod);
return modelMethod;
}
/**
* Find {@code @ModelAttribute} arguments also listed as {@code @SessionAttributes}.
*/
private List<String> findSessionAttributeArguments(HandlerMethod handlerMethod) {
List<String> result = new ArrayList<String>();
for (MethodParameter parameter : handlerMethod.getMethodParameters()) {
if (parameter.hasParameterAnnotation(ModelAttribute.class)) {
String name = getNameForParameter(parameter);
if (this.sessionAttributesHandler.isHandlerSessionAttribute(name, parameter.getParameterType())) {
result.add(name);
}
}
}
return result;
}
/**
* 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 more specific than {@code Object}
* <li>The actual return value type
* </ol>
* @param returnValue the value returned from a method invocation
* @param returnType the return type of the method
* @return the model name, never {@code null} nor empty
*/
public static String getNameForReturnValue(Object returnValue, MethodParameter returnType) {
ModelAttribute annotation = returnType.getMethodAnnotation(ModelAttribute.class);
if (annotation != null && StringUtils.hasText(annotation.value())) {
return annotation.value();
}
else {
Method method = returnType.getMethod();
Class<?> resolvedType = GenericTypeResolver.resolveReturnType(method, returnType.getContainingClass());
return Conventions.getVariableNameForReturnType(method, resolvedType, returnValue);
}
}
/**
* 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());
}
}
/**
* Add {@link BindingResult} attributes to the model for attributes that require it.
*/
private void updateBindingResult(NativeWebRequest request, ModelMap model) throws Exception {
List<String> keyNames = new ArrayList<String>(model.keySet());
for (String name : keyNames) {
Object value = model.get(name);
if (isBindingCandidate(name, value)) {
String bindingResultKey = BindingResult.MODEL_KEY_PREFIX + name;
if (!model.containsAttribute(bindingResultKey)) {
WebDataBinder dataBinder = dataBinderFactory.createBinder(request, value, name);
model.put(bindingResultKey, dataBinder.getBindingResult());
}
}
}
}
/**
* Whether the given attribute requires a {@link BindingResult} in the model.
*/
private boolean isBindingCandidate(String attributeName, Object value) {
if (attributeName.startsWith(BindingResult.MODEL_KEY_PREFIX)) {
return false;
}
Class<?> attrType = (value != null) ? value.getClass() : null;
if (this.sessionAttributesHandler.isHandlerSessionAttribute(attributeName, attrType)) {
return true;
}
return (value != null && !value.getClass().isArray() && !(value instanceof Collection) &&
!(value instanceof Map) && !BeanUtils.isSimpleValueType(value.getClass()));
}
private static class ModelMethod {
private final InvocableHandlerMethod handlerMethod;
private final Set<String> dependencies = new HashSet<String>();
private ModelMethod(InvocableHandlerMethod handlerMethod) {
this.handlerMethod = handlerMethod;
for (MethodParameter parameter : handlerMethod.getMethodParameters()) {
if (parameter.hasParameterAnnotation(ModelAttribute.class)) {
this.dependencies.add(getNameForParameter(parameter));
}
}
}
public InvocableHandlerMethod getHandlerMethod() {
return this.handlerMethod;
}
public boolean checkDependencies(ModelAndViewContainer mavContainer) {
for (String name : this.dependencies) {
if (!mavContainer.containsAttribute(name)) {
return false;
}
}
return true;
}
public List<String> getUnresolvedDependencies(ModelAndViewContainer mavContainer) {
List<String> result = new ArrayList<String>(this.dependencies.size());
for (String name : this.dependencies) {
if (!mavContainer.containsAttribute(name)) {
result.add(name);
}
}
return result;
}
@Override
public String toString() {
return this.handlerMethod.getMethod().toGenericString();
}
}
}