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/*
* ====================================================================
* 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 ch.boye.httpclientandroidlib.impl.client.cache;
import java.util.Map;
import ch.boye.httpclientandroidlib.Header;
import ch.boye.httpclientandroidlib.HeaderElement;
import ch.boye.httpclientandroidlib.ProtocolException;
import ch.boye.httpclientandroidlib.annotation.Immutable;
import ch.boye.httpclientandroidlib.client.cache.HeaderConstants;
import ch.boye.httpclientandroidlib.client.cache.HttpCacheEntry;
import ch.boye.httpclientandroidlib.client.methods.HttpRequestWrapper;
/**
* @since 4.1
*/
@Immutable
class ConditionalRequestBuilder {
/**
* When a {@link HttpCacheEntry} is stale but 'might' be used as a response
* to an {@link ch.boye.httpclientandroidlib.HttpRequest} we will attempt to revalidate
* the entry with the origin. Build the origin {@link ch.boye.httpclientandroidlib.HttpRequest}
* here and return it.
*
* @param request the original request from the caller
* @param cacheEntry the entry that needs to be re-validated
* @return the wrapped request
* @throws ProtocolException when I am unable to build a new origin request.
*/
public HttpRequestWrapper buildConditionalRequest(final HttpRequestWrapper request, final HttpCacheEntry cacheEntry)
throws ProtocolException {
final HttpRequestWrapper newRequest = HttpRequestWrapper.wrap(request.getOriginal());
newRequest.setHeaders(request.getAllHeaders());
final Header eTag = cacheEntry.getFirstHeader(HeaderConstants.ETAG);
if (eTag != null) {
newRequest.setHeader(HeaderConstants.IF_NONE_MATCH, eTag.getValue());
}
final Header lastModified = cacheEntry.getFirstHeader(HeaderConstants.LAST_MODIFIED);
if (lastModified != null) {
newRequest.setHeader(HeaderConstants.IF_MODIFIED_SINCE, lastModified.getValue());
}
boolean mustRevalidate = false;
for(final Header h : cacheEntry.getHeaders(HeaderConstants.CACHE_CONTROL)) {
for(final HeaderElement elt : h.getElements()) {
if (HeaderConstants.CACHE_CONTROL_MUST_REVALIDATE.equalsIgnoreCase(elt.getName())
|| HeaderConstants.CACHE_CONTROL_PROXY_REVALIDATE.equalsIgnoreCase(elt.getName())) {
mustRevalidate = true;
break;
}
}
}
if (mustRevalidate) {
newRequest.addHeader(HeaderConstants.CACHE_CONTROL, HeaderConstants.CACHE_CONTROL_MAX_AGE + "=0");
}
return newRequest;
}
/**
* When a {@link HttpCacheEntry} does not exist for a specific
* {@link ch.boye.httpclientandroidlib.HttpRequest} we attempt to see if an existing
* {@link HttpCacheEntry} is appropriate by building a conditional
* {@link ch.boye.httpclientandroidlib.HttpRequest} using the variants' ETag values.
* If no such values exist, the request is unmodified
*
* @param request the original request from the caller
* @param variants
* @return the wrapped request
*/
public HttpRequestWrapper buildConditionalRequestFromVariants(final HttpRequestWrapper request,
final Map<String, Variant> variants) {
final HttpRequestWrapper newRequest = HttpRequestWrapper.wrap(request.getOriginal());
newRequest.setHeaders(request.getAllHeaders());
// we do not support partial content so all etags are used
final StringBuilder etags = new StringBuilder();
boolean first = true;
for(final String etag : variants.keySet()) {
if (!first) {
etags.append(",");
}
first = false;
etags.append(etag);
}
newRequest.setHeader(HeaderConstants.IF_NONE_MATCH, etags.toString());
return newRequest;
}
/**
* Returns a request to unconditionally validate a cache entry with
* the origin. In certain cases (due to multiple intervening caches)
* our cache may actually receive a response to a normal conditional
* validation where the Date header is actually older than that of
* our current cache entry. In this case, the protocol recommendation
* is to retry the validation and force syncup with the origin.
* @param request client request we are trying to satisfy
* @param entry existing cache entry we are trying to validate
* @return an unconditional validation request
*/
public HttpRequestWrapper buildUnconditionalRequest(final HttpRequestWrapper request, final HttpCacheEntry entry) {
final HttpRequestWrapper newRequest = HttpRequestWrapper.wrap(request.getOriginal());
newRequest.setHeaders(request.getAllHeaders());
newRequest.addHeader(HeaderConstants.CACHE_CONTROL,HeaderConstants.CACHE_CONTROL_NO_CACHE);
newRequest.addHeader(HeaderConstants.PRAGMA,HeaderConstants.CACHE_CONTROL_NO_CACHE);
newRequest.removeHeaders(HeaderConstants.IF_RANGE);
newRequest.removeHeaders(HeaderConstants.IF_MATCH);
newRequest.removeHeaders(HeaderConstants.IF_NONE_MATCH);
newRequest.removeHeaders(HeaderConstants.IF_UNMODIFIED_SINCE);
newRequest.removeHeaders(HeaderConstants.IF_MODIFIED_SINCE);
return newRequest;
}
}
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