/*
* Copyright 2002-2012 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.annotation.Annotation;
import java.util.Map;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.BeanUtils;
import org.springframework.core.MethodParameter;
import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.validation.BindException;
import org.springframework.validation.Errors;
import org.springframework.web.bind.WebDataBinder;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.support.WebDataBinderFactory;
import org.springframework.web.bind.support.WebRequestDataBinder;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.method.support.HandlerMethodArgumentResolver;
import org.springframework.web.method.support.HandlerMethodReturnValueHandler;
import org.springframework.web.method.support.ModelAndViewContainer;
/**
* Resolves method arguments annotated with {@code @ModelAttribute} and handles
* return values from methods annotated with {@code @ModelAttribute}.
*
* <p>Model attributes are obtained from the model or if not found possibly
* created with a default constructor if it is available. Once created, the
* attributed is populated with request data via data binding and also
* validation may be applied if the argument is annotated with
* {@code @javax.validation.Valid}.
*
* <p>When this handler is created with {@code annotationNotRequired=true},
* any non-simple type argument and return value is regarded as a model
* attribute with or without the presence of an {@code @ModelAttribute}.
*
* @author Rossen Stoyanchev
* @since 3.1
*/
public class ModelAttributeMethodProcessor implements HandlerMethodArgumentResolver, HandlerMethodReturnValueHandler {
protected Log logger = LogFactory.getLog(this.getClass());
private final boolean annotationNotRequired;
/**
* @param annotationNotRequired if "true", non-simple method arguments and
* return values are considered model attributes with or without a
* {@code @ModelAttribute} annotation.
*/
public ModelAttributeMethodProcessor(boolean annotationNotRequired) {
this.annotationNotRequired = annotationNotRequired;
}
/**
* @return true if the parameter is annotated with {@link ModelAttribute}
* or in default resolution mode also if it is not a simple type.
*/
public boolean supportsParameter(MethodParameter parameter) {
if (parameter.hasParameterAnnotation(ModelAttribute.class)) {
return true;
}
else if (this.annotationNotRequired) {
return !BeanUtils.isSimpleProperty(parameter.getParameterType());
}
else {
return false;
}
}
/**
* Resolve the argument from the model or if not found instantiate it with
* its default if it is available. The model attribute is then populated
* with request values via data binding and optionally validated
* if {@code @java.validation.Valid} is present on the argument.
* @throws BindException if data binding and validation result in an error
* and the next method parameter is not of type {@link Errors}.
* @throws Exception if WebDataBinder initialization fails.
*/
public final Object resolveArgument(
MethodParameter parameter, ModelAndViewContainer mavContainer,
NativeWebRequest request, WebDataBinderFactory binderFactory)
throws Exception {
String name = ModelFactory.getNameForParameter(parameter);
Object attribute = (mavContainer.containsAttribute(name)) ?
mavContainer.getModel().get(name) : createAttribute(name, parameter, binderFactory, request);
WebDataBinder binder = binderFactory.createBinder(request, attribute, name);
if (binder.getTarget() != null) {
bindRequestParameters(binder, request);
validateIfApplicable(binder, parameter);
if (binder.getBindingResult().hasErrors()) {
if (isBindExceptionRequired(binder, parameter)) {
throw new BindException(binder.getBindingResult());
}
}
}
// Add resolved attribute and BindingResult at the end of the model
Map<String, Object> bindingResultModel = binder.getBindingResult().getModel();
mavContainer.removeAttributes(bindingResultModel);
mavContainer.addAllAttributes(bindingResultModel);
return binder.getTarget();
}
/**
* Extension point to create the model attribute if not found in the model.
* The default implementation uses the default constructor.
* @param attributeName the name of the attribute, never {@code null}
* @param parameter the method parameter
* @param binderFactory for creating WebDataBinder instance
* @param request the current request
* @return the created model attribute, never {@code null}
*/
protected Object createAttribute(String attributeName, MethodParameter parameter,
WebDataBinderFactory binderFactory, NativeWebRequest request) throws Exception {
return BeanUtils.instantiateClass(parameter.getParameterType());
}
/**
* Extension point to bind the request to the target object.
* @param binder the data binder instance to use for the binding
* @param request the current request
*/
protected void bindRequestParameters(WebDataBinder binder, NativeWebRequest request) {
((WebRequestDataBinder) binder).bind(request);
}
/**
* Validate the model attribute if applicable.
* <p>The default implementation checks for {@code @javax.validation.Valid}.
* @param binder the DataBinder to be used
* @param parameter the method parameter
*/
protected void validateIfApplicable(WebDataBinder binder, MethodParameter parameter) {
Annotation[] annotations = parameter.getParameterAnnotations();
for (Annotation annot : annotations) {
if (annot.annotationType().getSimpleName().startsWith("Valid")) {
Object hints = AnnotationUtils.getValue(annot);
binder.validate(hints instanceof Object[] ? (Object[]) hints : new Object[] {hints});
break;
}
}
}
/**
* Whether to raise a {@link BindException} on validation errors.
* @param binder the data binder used to perform data binding
* @param parameter the method argument
* @return {@code true} if the next method argument is not of type {@link Errors}.
*/
protected boolean isBindExceptionRequired(WebDataBinder binder, MethodParameter parameter) {
int i = parameter.getParameterIndex();
Class<?>[] paramTypes = parameter.getMethod().getParameterTypes();
boolean hasBindingResult = (paramTypes.length > (i + 1) && Errors.class.isAssignableFrom(paramTypes[i + 1]));
return !hasBindingResult;
}
/**
* Return {@code true} if there is a method-level {@code @ModelAttribute}
* or if it is a non-simple type when {@code annotationNotRequired=true}.
*/
public boolean supportsReturnType(MethodParameter returnType) {
if (returnType.getMethodAnnotation(ModelAttribute.class) != null) {
return true;
}
else if (this.annotationNotRequired) {
return !BeanUtils.isSimpleProperty(returnType.getParameterType());
}
else {
return false;
}
}
/**
* Add non-null return values to the {@link ModelAndViewContainer}.
*/
public void handleReturnValue(
Object returnValue, MethodParameter returnType,
ModelAndViewContainer mavContainer, NativeWebRequest webRequest)
throws Exception {
if (returnValue != null) {
String name = ModelFactory.getNameForReturnValue(returnValue, returnType);
mavContainer.addAttribute(name, returnValue);
}
}
}