Spring Framework example source code file (WebArgumentResolver.java)

This example Spring Framework source code file (WebArgumentResolver.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Spring Framework tags/keywords

exception, exception, nativewebrequest, nativewebrequest, object, object, unresolved, webargumentresolver, webargumentresolver

The Spring Framework WebArgumentResolver.java source code

/*
 * Copyright 2002-2008 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.bind.support;

import org.springframework.core.MethodParameter;
import org.springframework.web.context.request.NativeWebRequest;

/**
 * SPI for resolving custom arguments for a specific handler method parameter.
 * Typically implemented to detect sppecial parameter types, resolving
 * well-known argument values for them.
 *
 * <p>A typical implementation could look like as follows:
 *
 * <pre class="code">
 * private static class MySpecialArgumentResolver implements ArgumentResolver {
 *
 *   public Object resolveArgument(NativeWebRequest webRequest, MethodParameter methodParameter) {
 *     if (methodParameter.getParameterType().equals(MySpecialArg.class)) {
 *       return new MySpecialArg("myValue");
 *     }
 *     return UNRESOLVED;
 *   }
 * }</pre>
 *
 * @author Juergen Hoeller
 * @since 2.5.2
 * @see org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter#setCustomArgumentResolvers
 * @see org.springframework.web.portlet.mvc.annotation.AnnotationMethodHandlerAdapter#setCustomArgumentResolvers
 */
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
	 */
	Object resolveArgument(MethodParameter methodParameter, NativeWebRequest webRequest) throws Exception;

}