001/*
002 * ====================================================================
003 * Licensed to the Apache Software Foundation (ASF) under one
004 * or more contributor license agreements.  See the NOTICE file
005 * distributed with this work for additional information
006 * regarding copyright ownership.  The ASF licenses this file
007 * to you under the Apache License, Version 2.0 (the
008 * "License"); you may not use this file except in compliance
009 * with the License.  You may obtain a copy of the License at
010 *
011 *   http://www.apache.org/licenses/LICENSE-2.0
012 *
013 * Unless required by applicable law or agreed to in writing,
014 * software distributed under the License is distributed on an
015 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
016 * KIND, either express or implied.  See the License for the
017 * specific language governing permissions and limitations
018 * under the License.
019 * ====================================================================
020 *
021 * This software consists of voluntary contributions made by many
022 * individuals on behalf of the Apache Software Foundation.  For more
023 * information on the Apache Software Foundation, please see
024 * <http://www.apache.org/>.
025 *
026 */
027
028package org.apache.http.protocol;
029
030import java.io.IOException;
031
032import org.apache.http.HttpException;
033import org.apache.http.HttpResponse;
034import org.apache.http.HttpResponseInterceptor;
035import org.apache.http.HttpStatus;
036import org.apache.http.annotation.ThreadingBehavior;
037import org.apache.http.annotation.Contract;
038import org.apache.http.util.Args;
039
040/**
041 * ResponseDate is responsible for adding {@code Date} header to the
042 * outgoing responses. This interceptor is recommended for server side protocol
043 * processors.
044 *
045 * @since 4.0
046 */
047@Contract(threading = ThreadingBehavior.SAFE)
048public class ResponseDate implements HttpResponseInterceptor {
049
050    private static final HttpDateGenerator DATE_GENERATOR = new HttpDateGenerator();
051
052    public ResponseDate() {
053        super();
054    }
055
056    @Override
057    public void process(final HttpResponse response, final HttpContext context)
058            throws HttpException, IOException {
059        Args.notNull(response, "HTTP response");
060        final int status = response.getStatusLine().getStatusCode();
061        if ((status >= HttpStatus.SC_OK) &&
062            !response.containsHeader(HTTP.DATE_HEADER)) {
063            final String httpdate = DATE_GENERATOR.getCurrentDate();
064            response.setHeader(HTTP.DATE_HEADER, httpdate);
065        }
066    }
067
068}