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HttpComponents HttpClient - Cache
/*
* ====================================================================
* 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
* cacheableStatuses =
new HashSet(Arrays.asList(HttpStatus.SC_OK,
HttpStatus.SC_NON_AUTHORITATIVE_INFORMATION,
HttpStatus.SC_MULTIPLE_CHOICES,
HttpStatus.SC_MOVED_PERMANENTLY,
HttpStatus.SC_GONE));
private static final Set uncacheableStatuses =
new HashSet(Arrays.asList(HttpStatus.SC_PARTIAL_CONTENT,
HttpStatus.SC_SEE_OTHER));
/**
* Define a cache policy that limits the size of things that should be stored
* in the cache to a maximum of {@link HttpResponse} bytes in size.
*
* @param maxObjectSizeBytes the size to limit items into the cache
* @param sharedCache whether to behave as a shared cache (true) or a
* non-shared/private cache (false)
*/
public ResponseCachingPolicy(long maxObjectSizeBytes, boolean sharedCache) {
this.maxObjectSizeBytes = maxObjectSizeBytes;
this.sharedCache = sharedCache;
}
/**
* Determines if an HttpResponse can be cached.
*
* @param httpMethod What type of request was this, a GET, PUT, other?
* @param response The origin response
* @return true if response is cacheable
*/
public boolean isResponseCacheable(String httpMethod, HttpResponse response) {
boolean cacheable = false;
if (!HeaderConstants.GET_METHOD.equals(httpMethod)) {
log.debug("Response was not cacheable.");
return false;
}
int status = response.getStatusLine().getStatusCode();
if (cacheableStatuses.contains(status)) {
// these response codes MAY be cached
cacheable = true;
} else if (uncacheableStatuses.contains(status)) {
return false;
} else if (unknownStatusCode(status)) {
// a response with an unknown status code MUST NOT be
// cached
return false;
}
Header contentLength = response.getFirstHeader(HTTP.CONTENT_LEN);
if (contentLength != null) {
int contentLengthValue = Integer.parseInt(contentLength.getValue());
if (contentLengthValue > this.maxObjectSizeBytes)
return false;
}
Header[] ageHeaders = response.getHeaders(HeaderConstants.AGE);
if (ageHeaders.length > 1)
return false;
Header[] expiresHeaders = response.getHeaders(HeaderConstants.EXPIRES);
if (expiresHeaders.length > 1)
return false;
Header[] dateHeaders = response.getHeaders(HTTP.DATE_HEADER);
if (dateHeaders.length != 1)
return false;
try {
DateUtils.parseDate(dateHeaders[0].getValue());
} catch (DateParseException dpe) {
return false;
}
for (Header varyHdr : response.getHeaders(HeaderConstants.VARY)) {
for (HeaderElement elem : varyHdr.getElements()) {
if ("*".equals(elem.getName())) {
return false;
}
}
}
if (isExplicitlyNonCacheable(response))
return false;
return (cacheable || isExplicitlyCacheable(response));
}
private boolean unknownStatusCode(int status) {
if (status >= 100 && status <= 101) return false;
if (status >= 200 && status <= 206) return false;
if (status >= 300 && status <= 307) return false;
if (status >= 400 && status <= 417) return false;
if (status >= 500 && status <= 505) return false;
return true;
}
protected boolean isExplicitlyNonCacheable(HttpResponse response) {
Header[] cacheControlHeaders = response.getHeaders(HeaderConstants.CACHE_CONTROL);
for (Header header : cacheControlHeaders) {
for (HeaderElement elem : header.getElements()) {
if (HeaderConstants.CACHE_CONTROL_NO_STORE.equals(elem.getName())
|| HeaderConstants.CACHE_CONTROL_NO_CACHE.equals(elem.getName())
|| (sharedCache && HeaderConstants.PRIVATE.equals(elem.getName()))) {
return true;
}
}
}
return false;
}
protected boolean hasCacheControlParameterFrom(HttpMessage msg, String[] params) {
Header[] cacheControlHeaders = msg.getHeaders(HeaderConstants.CACHE_CONTROL);
for (Header header : cacheControlHeaders) {
for (HeaderElement elem : header.getElements()) {
for (String param : params) {
if (param.equalsIgnoreCase(elem.getName())) {
return true;
}
}
}
}
return false;
}
protected boolean isExplicitlyCacheable(HttpResponse response) {
if (response.getFirstHeader(HeaderConstants.EXPIRES) != null)
return true;
String[] cacheableParams = { HeaderConstants.CACHE_CONTROL_MAX_AGE, "s-maxage",
HeaderConstants.CACHE_CONTROL_MUST_REVALIDATE,
HeaderConstants.CACHE_CONTROL_PROXY_REVALIDATE,
HeaderConstants.PUBLIC
};
return hasCacheControlParameterFrom(response, cacheableParams);
}
/**
* Determine if the {@link HttpResponse} gotten from the origin is a
* cacheable response.
*
* @param request the {@link HttpRequest} that generated an origin hit
* @param response the {@link HttpResponse} from the origin
* @return true if response is cacheable
*/
public boolean isResponseCacheable(HttpRequest request, HttpResponse response) {
if (requestProtocolGreaterThanAccepted(request)) {
log.debug("Response was not cacheable.");
return false;
}
String[] uncacheableRequestDirectives = { HeaderConstants.CACHE_CONTROL_NO_STORE };
if (hasCacheControlParameterFrom(request,uncacheableRequestDirectives)) {
return false;
}
if (request.getRequestLine().getUri().contains("?") &&
(!isExplicitlyCacheable(response) || from1_0Origin(response))) {
log.debug("Response was not cacheable.");
return false;
}
if (expiresHeaderLessOrEqualToDateHeaderAndNoCacheControl(response)) {
return false;
}
if (sharedCache) {
Header[] authNHeaders = request.getHeaders(HeaderConstants.AUTHORIZATION);
if (authNHeaders != null && authNHeaders.length > 0) {
String[] authCacheableParams = {
"s-maxage", HeaderConstants.CACHE_CONTROL_MUST_REVALIDATE, HeaderConstants.PUBLIC
};
return hasCacheControlParameterFrom(response, authCacheableParams);
}
}
String method = request.getRequestLine().getMethod();
return isResponseCacheable(method, response);
}
private boolean expiresHeaderLessOrEqualToDateHeaderAndNoCacheControl(
HttpResponse response) {
if (response.getFirstHeader(HeaderConstants.CACHE_CONTROL) != null) return false;
Header expiresHdr = response.getFirstHeader(HeaderConstants.EXPIRES);
Header dateHdr = response.getFirstHeader(HTTP.DATE_HEADER);
if (expiresHdr == null || dateHdr == null) return false;
try {
Date expires = DateUtils.parseDate(expiresHdr.getValue());
Date date = DateUtils.parseDate(dateHdr.getValue());
return expires.equals(date) || expires.before(date);
} catch (DateParseException dpe) {
return false;
}
}
private boolean from1_0Origin(HttpResponse response) {
Header via = response.getFirstHeader(HeaderConstants.VIA);
if (via != null) {
for(HeaderElement elt : via.getElements()) {
String proto = elt.toString().split("\\s")[0];
if (proto.contains("/")) {
return proto.equals("HTTP/1.0");
} else {
return proto.equals("1.0");
}
}
}
return HttpVersion.HTTP_1_0.equals(response.getProtocolVersion());
}
private boolean requestProtocolGreaterThanAccepted(HttpRequest req) {
return req.getProtocolVersion().compareToVersion(HttpVersion.HTTP_1_1) > 0;
}
}