001// Copyright 2011 The Apache Software Foundation
002//
003// Licensed under the Apache License, Version 2.0 (the "License");
004// you may not use this file except in compliance with the License.
005// You may obtain a copy of the License at
006//
007// http://www.apache.org/licenses/LICENSE-2.0
008//
009// Unless required by applicable law or agreed to in writing, software
010// distributed under the License is distributed on an "AS IS" BASIS,
011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012// See the License for the specific language governing permissions and
013// limitations under the License.
014package org.apache.tapestry5.http.services;
015
016import javax.servlet.http.HttpServletRequest;
017
018import org.apache.tapestry5.ioc.annotations.UsesOrderedConfiguration;
019
020/**
021 * Service that converts the body of an HTTP request to a given target class.
022 * Each implementation, which should be contributed to the {@link HttpRequestBodyConverter} service,
023 * should check whether it can actually handled that request. If not, it should return <code>null</code>,
024 * which means trying the next HttpRequestBodyConverter instance.
025 */
026@UsesOrderedConfiguration(HttpRequestBodyConverter.class)
027public interface HttpRequestBodyConverter
028{
029
030    /**
031     * Converts the body of this request. If this implementation cannot handle this request,
032     * probably by not handling its content type, it should return <code>null</code>.
033     * In addition, if the request body is empty, this method should also return
034     * <code>null</code>.
035     * @param request an {@linkplain HttpServletRequest}.
036     * @param type the target type.
037     * @return an object of the target type or <code>null</code>.
038     */
039    <T> T convert(HttpServletRequest request, Class<T> type);
040    
041}