/*
* 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 org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.core.MethodParameter;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.web.bind.support.WebArgumentResolver;
import org.springframework.web.bind.support.WebDataBinderFactory;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.method.support.HandlerMethodArgumentResolver;
import org.springframework.web.method.support.ModelAndViewContainer;
/**
* An abstract base class adapting a {@link WebArgumentResolver} to the
* {@link HandlerMethodArgumentResolver} contract.
*
* <p><strong>Note:</strong> This class is provided for backwards compatibility.
* However it is recommended to re-write a {@code WebArgumentResolver} as
* {@code HandlerMethodArgumentResolver}. Since {@link #supportsParameter}
* can only be implemented by actually resolving the value and then checking
* the result is not {@code WebArgumentResolver#UNRESOLVED} any exceptions
* raised must be absorbed and ignored since it's not clear whether the adapter
* doesn't support the parameter or whether it failed for an internal reason.
* The {@code HandlerMethodArgumentResolver} contract also provides access to
* model attributes and to {@code WebDataBinderFactory} (for type conversion).
*
* @author Arjen Poutsma
* @author Rossen Stoyanchev
* @since 3.1
*/
public abstract class AbstractWebArgumentResolverAdapter implements HandlerMethodArgumentResolver {
private final Log logger = LogFactory.getLog(this.getClass());
private final WebArgumentResolver adaptee;
/**
* Create a new instance.
*/
public AbstractWebArgumentResolverAdapter(WebArgumentResolver adaptee) {
Assert.notNull(adaptee, "'adaptee' must not be null");
this.adaptee = adaptee;
}
/**
* Actually resolve the value and check the resolved value is not
* {@link WebArgumentResolver#UNRESOLVED} absorbing _any_ exceptions.
*/
public boolean supportsParameter(MethodParameter parameter) {
try {
NativeWebRequest webRequest = getWebRequest();
Object result = this.adaptee.resolveArgument(parameter, webRequest);
if (result == WebArgumentResolver.UNRESOLVED) {
return false;
}
else {
return ClassUtils.isAssignableValue(parameter.getParameterType(), result);
}
}
catch (Exception ex) {
// ignore (see class-level doc)
logger.debug("Error in checking support for parameter [" + parameter + "], message: " + ex.getMessage());
return false;
}
}
/**
* Required for access to NativeWebRequest in {@link #supportsParameter}.
*/
protected abstract NativeWebRequest getWebRequest();
/**
* Delegate to the {@link WebArgumentResolver} instance.
* @exception IllegalStateException if the resolved value is not assignable
* to the method parameter.
*/
public Object resolveArgument(
MethodParameter parameter, ModelAndViewContainer mavContainer,
NativeWebRequest webRequest, WebDataBinderFactory binderFactory)
throws Exception {
Class<?> paramType = parameter.getParameterType();
Object result = this.adaptee.resolveArgument(parameter, webRequest);
if (result == WebArgumentResolver.UNRESOLVED || !ClassUtils.isAssignableValue(paramType, result)) {
throw new IllegalStateException(
"Standard argument type [" + paramType.getName() + "] in method " + parameter.getMethod() +
"resolved to incompatible value of type [" + (result != null ? result.getClass() : null) +
"]. Consider declaring the argument type in a less specific fashion.");
}
return result;
}
}