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/*
 * $Header: /home/cvs/jakarta-commons/httpclient/src/java/org/apache/commons/httpclient/methods/ExpectContinueMethod.java,v 1.5.2.3 2004/02/22 18:21:15 olegk Exp $
 * $Revision: 1.5.2.3 $
 * $Date: 2004/02/22 18:21:15 $
 *
 * ====================================================================
 *
 *  Copyright 2003-2004 The Apache Software Foundation
 *
 *  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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * .
 *
 * [Additional notices, if required by prior licensing conditions]
 *
 */

package org.apache.commons.httpclient.methods;

import java.io.IOException;
import org.apache.commons.httpclient.HttpConnection;
import org.apache.commons.httpclient.HttpException;
import org.apache.commons.httpclient.HttpState;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * 

* This abstract class serves as a foundation for all HTTP methods * that support 'Expect: 100-continue' handshake. *

* *

* The purpose of the 100 (Continue) status (refer to section 10.1.1 * of the RFC 2616 for more details) is to allow a client that is * sending a request message with a request body to determine if the * origin server is willing to accept the request (based on the request * headers) before the client sends the request body. In some cases, * it might either be inappropriate or highly inefficient for the * client to send the body if the server will reject the message * without looking at the body. *

* *

* 'Expect: 100-continue' handshake should be used with caution, * as it may cause problems with HTTP servers and proxies that * do not support HTTP/1.1 protocol. *

* * @author Oleg Kalnichevski * * @since 2.0beta1 */ public abstract class ExpectContinueMethod extends GetMethod { /** This flag specifies whether "expect: 100-continue" handshake is * to be used prior to sending the request body */ private boolean useExpectHeader = false; /** LOG object for this class. */ private static final Log LOG = LogFactory.getLog(ExpectContinueMethod.class); /** * No-arg constructor. * * @since 2.0 */ public ExpectContinueMethod() { super(); } /** * Constructor specifying a URI. * * @param uri either an absolute or relative URI * * @since 2.0 */ public ExpectContinueMethod(String uri) { super(uri); } /** * Constructor specifying a URI and a tempDir. * * @param uri either an absolute or relative URI * @param tempDir directory to store temp files in * * @deprecated the client is responsible for disk I/O * @since 2.0 */ public ExpectContinueMethod(String uri, String tempDir) { super(uri, tempDir); } /** * Constructor specifying a URI, tempDir and tempFile. * * @param uri either an absolute or relative URI * @param tempDir directory to store temp files in * @param tempFile file to store temporary data in * * @deprecated the client is responsible for disk I/O * @since 2.0 */ public ExpectContinueMethod(String uri, String tempDir, String tempFile) { super(uri, tempDir, tempFile); } /** *

* Returns true if the 'Expect: 100-Continue' handshake * is activated. The purpose of the 'Expect: 100-Continue' * handshake to allow a client that is sending a request message * with a request body to determine if the origin server is * willing to accept the request (based on the request headers) * before the client sends the request body. *

* * @return true if 'Expect: 100-Continue' handshake is to * be used, false otherwise. * * @since 2.0beta1 */ public boolean getUseExpectHeader() { return this.useExpectHeader; } /** *

* Activates 'Expect: 100-Continue' handshake. The purpose of * the 'Expect: 100-Continue' handshake to allow a client that is * sending a request message with a request body to determine if * the origin server is willing to accept the request (based on * the request headers) before the client sends the request body. *

* *

* The use of the 'Expect: 100-continue' handshake can result in * noticable peformance improvement for entity enclosing requests * (such as POST and PUT) that require the target server's * authentication. *

* *

* 'Expect: 100-continue' handshake should be used with * caution, as it may cause problems with HTTP servers and * proxies that do not support HTTP/1.1 protocol. *

* * @param value boolean value * * * @since 2.0beta1 */ public void setUseExpectHeader(boolean value) { this.useExpectHeader = value; } /** * Returns true if there is a request body to be sent. * 'Expect: 100-continue' handshake may not be used if request * body is not present * * @return boolean * * @since 2.0beta1 */ protected abstract boolean hasRequestContent(); /** * Sets the Expect header if it has not already been set, * in addition to the "standard" set of headers. * * @param state the {@link HttpState state} information associated with this method * @param conn the {@link HttpConnection connection} used to execute * this HTTP method * * @throws IOException if an I/O (transport) error occurs * @throws HttpException if a protocol exception occurs. * @throws HttpRecoverableException if a recoverable transport error occurs. * Usually this kind of exceptions can be recovered from by * retrying the HTTP method */ protected void addRequestHeaders(HttpState state, HttpConnection conn) throws IOException, HttpException { LOG.trace("enter ExpectContinueMethod.addRequestHeaders(HttpState, HttpConnection)"); super.addRequestHeaders(state, conn); // If the request is being retried, the header may already be present boolean headerPresent = (getRequestHeader("Expect") != null); // See if the expect header should be sent // = HTTP/1.1 or higher // = request body present if (getUseExpectHeader() && isHttp11() && hasRequestContent()) { if (!headerPresent) { setRequestHeader("Expect", "100-continue"); } } else { if (headerPresent) { removeRequestHeader("Expect"); } } } }


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