| /* |
| * $HeadURL: http://svn.apache.org/repos/asf/httpcomponents/httpcore/trunk/module-main/src/main/java/org/apache/http/impl/DefaultConnectionReuseStrategy.java $ |
| * $Revision: 602537 $ |
| * $Date: 2007-12-08 11:42:06 -0800 (Sat, 08 Dec 2007) $ |
| * |
| * ==================================================================== |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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 |
| * <http://www.apache.org/>. |
| * |
| */ |
| |
| package org.apache.http.impl; |
| |
| import org.apache.http.ConnectionReuseStrategy; |
| import org.apache.http.HttpConnection; |
| import org.apache.http.HeaderIterator; |
| import org.apache.http.HttpEntity; |
| import org.apache.http.HttpResponse; |
| import org.apache.http.HttpVersion; |
| import org.apache.http.ParseException; |
| import org.apache.http.ProtocolVersion; |
| import org.apache.http.protocol.HTTP; |
| import org.apache.http.protocol.HttpContext; |
| import org.apache.http.protocol.ExecutionContext; |
| import org.apache.http.TokenIterator; |
| import org.apache.http.message.BasicTokenIterator; |
| |
| /** |
| * Default implementation of a strategy deciding about connection re-use. |
| * The default implementation first checks some basics, for example |
| * whether the connection is still open or whether the end of the |
| * request entity can be determined without closing the connection. |
| * If these checks pass, the tokens in the "Connection" header will |
| * be examined. In the absence of a "Connection" header, the |
| * non-standard but commonly used "Proxy-Connection" header takes |
| * it's role. A token "close" indicates that the connection cannot |
| * be reused. If there is no such token, a token "keep-alive" indicates |
| * that the connection should be re-used. If neither token is found, |
| * or if there are no "Connection" headers, the default policy for |
| * the HTTP version is applied. Since HTTP/1.1, connections are re-used |
| * by default. Up until HTTP/1.0, connections are not re-used by default. |
| * |
| * @author <a href="mailto:oleg at ural.ru">Oleg Kalnichevski</a> |
| * @author <a href="mailto:rolandw at apache.org">Roland Weber</a> |
| * |
| * @version $Revision: 602537 $ |
| * |
| * @since 4.0 |
| * |
| * @deprecated Please use {@link java.net.URL#openConnection} instead. |
| * Please visit <a href="http://android-developers.blogspot.com/2011/09/androids-http-clients.html">this webpage</a> |
| * for further details. |
| */ |
| @Deprecated |
| public class DefaultConnectionReuseStrategy |
| implements ConnectionReuseStrategy { |
| |
| public DefaultConnectionReuseStrategy() { |
| super(); |
| } |
| |
| // see interface ConnectionReuseStrategy |
| public boolean keepAlive(final HttpResponse response, |
| final HttpContext context) { |
| if (response == null) { |
| throw new IllegalArgumentException |
| ("HTTP response may not be null."); |
| } |
| if (context == null) { |
| throw new IllegalArgumentException |
| ("HTTP context may not be null."); |
| } |
| |
| HttpConnection conn = (HttpConnection) |
| context.getAttribute(ExecutionContext.HTTP_CONNECTION); |
| |
| if (conn != null && !conn.isOpen()) |
| return false; |
| // do NOT check for stale connection, that is an expensive operation |
| |
| // Check for a self-terminating entity. If the end of the entity will |
| // be indicated by closing the connection, there is no keep-alive. |
| HttpEntity entity = response.getEntity(); |
| ProtocolVersion ver = response.getStatusLine().getProtocolVersion(); |
| if (entity != null) { |
| if (entity.getContentLength() < 0) { |
| if (!entity.isChunked() || |
| ver.lessEquals(HttpVersion.HTTP_1_0)) { |
| // if the content length is not known and is not chunk |
| // encoded, the connection cannot be reused |
| return false; |
| } |
| } |
| } |
| |
| // Check for the "Connection" header. If that is absent, check for |
| // the "Proxy-Connection" header. The latter is an unspecified and |
| // broken but unfortunately common extension of HTTP. |
| HeaderIterator hit = response.headerIterator(HTTP.CONN_DIRECTIVE); |
| if (!hit.hasNext()) |
| hit = response.headerIterator("Proxy-Connection"); |
| |
| // Experimental usage of the "Connection" header in HTTP/1.0 is |
| // documented in RFC 2068, section 19.7.1. A token "keep-alive" is |
| // used to indicate that the connection should be persistent. |
| // Note that the final specification of HTTP/1.1 in RFC 2616 does not |
| // include this information. Neither is the "Connection" header |
| // mentioned in RFC 1945, which informally describes HTTP/1.0. |
| // |
| // RFC 2616 specifies "close" as the only connection token with a |
| // specific meaning: it disables persistent connections. |
| // |
| // The "Proxy-Connection" header is not formally specified anywhere, |
| // but is commonly used to carry one token, "close" or "keep-alive". |
| // The "Connection" header, on the other hand, is defined as a |
| // sequence of tokens, where each token is a header name, and the |
| // token "close" has the above-mentioned additional meaning. |
| // |
| // To get through this mess, we treat the "Proxy-Connection" header |
| // in exactly the same way as the "Connection" header, but only if |
| // the latter is missing. We scan the sequence of tokens for both |
| // "close" and "keep-alive". As "close" is specified by RFC 2068, |
| // it takes precedence and indicates a non-persistent connection. |
| // If there is no "close" but a "keep-alive", we take the hint. |
| |
| if (hit.hasNext()) { |
| try { |
| TokenIterator ti = createTokenIterator(hit); |
| boolean keepalive = false; |
| while (ti.hasNext()) { |
| final String token = ti.nextToken(); |
| if (HTTP.CONN_CLOSE.equalsIgnoreCase(token)) { |
| return false; |
| } else if (HTTP.CONN_KEEP_ALIVE.equalsIgnoreCase(token)) { |
| // continue the loop, there may be a "close" afterwards |
| keepalive = true; |
| } |
| } |
| if (keepalive) |
| return true; |
| // neither "close" nor "keep-alive", use default policy |
| |
| } catch (ParseException px) { |
| // invalid connection header means no persistent connection |
| // we don't have logging in HttpCore, so the exception is lost |
| return false; |
| } |
| } |
| |
| // default since HTTP/1.1 is persistent, before it was non-persistent |
| return !ver.lessEquals(HttpVersion.HTTP_1_0); |
| } |
| |
| |
| /** |
| * Creates a token iterator from a header iterator. |
| * This method can be overridden to replace the implementation of |
| * the token iterator. |
| * |
| * @param hit the header iterator |
| * |
| * @return the token iterator |
| */ |
| protected TokenIterator createTokenIterator(HeaderIterator hit) { |
| return new BasicTokenIterator(hit); |
| } |
| } |
