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.HttpEntity;
033import org.apache.http.HttpEntityEnclosingRequest;
034import org.apache.http.HttpException;
035import org.apache.http.HttpRequest;
036import org.apache.http.HttpRequestInterceptor;
037import org.apache.http.HttpVersion;
038import org.apache.http.ProtocolVersion;
039import org.apache.http.annotation.ThreadingBehavior;
040import org.apache.http.annotation.Contract;
041import org.apache.http.params.CoreProtocolPNames;
042import org.apache.http.util.Args;
043
044/**
045 * RequestExpectContinue is responsible for enabling the 'expect-continue'
046 * handshake by adding {@code Expect} header. This interceptor is
047 * recommended for client side protocol processors.
048 *
049 * @since 4.0
050 */
051@Contract(threading = ThreadingBehavior.IMMUTABLE)
052@SuppressWarnings("deprecation")
053public class RequestExpectContinue implements HttpRequestInterceptor {
054
055    private final boolean activeByDefault;
056
057    /**
058     * @deprecated (4.3) use {@link org.apache.http.protocol.RequestExpectContinue#RequestExpectContinue(boolean)}
059     */
060    @Deprecated
061    public RequestExpectContinue() {
062        this(false);
063    }
064
065    /**
066     * @since 4.3
067     */
068    public RequestExpectContinue(final boolean activeByDefault) {
069        super();
070        this.activeByDefault = activeByDefault;
071    }
072
073    @Override
074    public void process(final HttpRequest request, final HttpContext context)
075            throws HttpException, IOException {
076        Args.notNull(request, "HTTP request");
077
078        if (!request.containsHeader(HTTP.EXPECT_DIRECTIVE)) {
079            if (request instanceof HttpEntityEnclosingRequest) {
080                final ProtocolVersion ver = request.getRequestLine().getProtocolVersion();
081                final HttpEntity entity = ((HttpEntityEnclosingRequest)request).getEntity();
082                // Do not send the expect header if request body is known to be empty
083                if (entity != null
084                        && entity.getContentLength() != 0 && !ver.lessEquals(HttpVersion.HTTP_1_0)) {
085                    final boolean active = request.getParams().getBooleanParameter(
086                            CoreProtocolPNames.USE_EXPECT_CONTINUE, this.activeByDefault);
087                    if (active) {
088                        request.addHeader(HTTP.EXPECT_DIRECTIVE, HTTP.EXPECT_CONTINUE);
089                    }
090                }
091            }
092        }
093    }
094
095}