org.springframework.web.bind.support.WebArgumentResolver Maven / Gradle / Ivy
/*
* Copyright 2002-2017 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
*
* https://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.bind.support;
import org.springframework.core.MethodParameter;
import org.springframework.lang.Nullable;
import org.springframework.web.context.request.NativeWebRequest;
/**
* SPI for resolving custom arguments for a specific handler method parameter.
* Typically implemented to detect special parameter types, resolving
* well-known argument values for them.
*
* A typical implementation could look like as follows:
*
*
* public class MySpecialArgumentResolver implements WebArgumentResolver {
*
* public Object resolveArgument(MethodParameter methodParameter, NativeWebRequest webRequest) {
* if (methodParameter.getParameterType().equals(MySpecialArg.class)) {
* return new MySpecialArg("myValue");
* }
* return UNRESOLVED;
* }
* }
*
* @author Juergen Hoeller
* @since 2.5.2
* @see org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter#setCustomArgumentResolvers
*/
@FunctionalInterface
public interface WebArgumentResolver {
/**
* Marker to be returned when the resolver does not know how to
* handle the given method parameter.
*/
Object UNRESOLVED = new Object();
/**
* Resolve an argument for the given handler method parameter within the given web request.
* @param methodParameter the handler method parameter to resolve
* @param webRequest the current web request, allowing access to the native request as well
* @return the argument value, or {@code UNRESOLVED} if not resolvable
* @throws Exception in case of resolution failure
*/
@Nullable
Object resolveArgument(MethodParameter methodParameter, NativeWebRequest webRequest) throws Exception;
}