/*
* Copyright 2002-2011 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 javax.servlet.ServletException;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.core.MethodParameter;
import org.springframework.web.bind.WebDataBinder;
import org.springframework.web.context.request.NativeWebRequest;
/**
* Resolves method arguments annotated with {@code @Value}.
*
* <p>An {@code @Value} does not have a name but gets resolved from the default
* value string, which may contain ${...} placeholder or Spring Expression
* Language #{...} expressions.
*
* <p>A {@link WebDataBinder} may be invoked to apply type conversion to
* resolved argument value.
*
* @author Rossen Stoyanchev
* @since 3.1
*/
public class ExpressionValueMethodArgumentResolver extends AbstractNamedValueMethodArgumentResolver {
/**
* @param beanFactory a bean factory to use for resolving ${...}
* placeholder and #{...} SpEL expressions in default values;
* or {@code null} if default values are not expected to contain expressions
*/
public ExpressionValueMethodArgumentResolver(ConfigurableBeanFactory beanFactory) {
super(beanFactory);
}
public boolean supportsParameter(MethodParameter parameter) {
return parameter.hasParameterAnnotation(Value.class);
}
@Override
protected NamedValueInfo createNamedValueInfo(MethodParameter parameter) {
Value annotation = parameter.getParameterAnnotation(Value.class);
return new ExpressionValueNamedValueInfo(annotation);
}
@Override
protected Object resolveName(String name, MethodParameter parameter, NativeWebRequest webRequest)
throws Exception {
// No name to resolve
return null;
}
@Override
protected void handleMissingValue(String name, MethodParameter parameter) throws ServletException {
throw new UnsupportedOperationException("@Value is never required: " + parameter.getMethod());
}
private static class ExpressionValueNamedValueInfo extends NamedValueInfo {
private ExpressionValueNamedValueInfo(Value annotation) {
super("@Value", false, annotation.value());
}
}
}