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Apache 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 final Set uncacheableStatuses;
/**
* 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)
* @param neverCache1_0ResponsesWithQueryString true to never cache HTTP 1.0 responses with a query string, false
* to cache if explicit cache headers are found.
* @param allow303Caching if this policy is permitted to cache 303 response
*/
public ResponseCachingPolicy(final long maxObjectSizeBytes,
final boolean sharedCache,
final boolean neverCache1_0ResponsesWithQueryString,
final boolean allow303Caching) {
this.maxObjectSizeBytes = maxObjectSizeBytes;
this.sharedCache = sharedCache;
this.neverCache1_0ResponsesWithQueryString = neverCache1_0ResponsesWithQueryString;
if (allow303Caching) {
uncacheableStatuses = new HashSet(
Arrays.asList(HttpStatus.SC_PARTIAL_CONTENT));
} else {
uncacheableStatuses = new HashSet(Arrays.asList(
HttpStatus.SC_PARTIAL_CONTENT, HttpStatus.SC_SEE_OTHER));
}
}
/**
* 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 {@code true} if response is cacheable
*/
public boolean isResponseCacheable(final String httpMethod, final HttpResponse response) {
boolean cacheable = false;
if (!(HeaderConstants.GET_METHOD.equals(httpMethod) ||
HeaderConstants.HEAD_METHOD.equals(httpMethod))) {
log.debug("Response was not cacheable.");
return false;
}
final 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;
}
final Header contentLength = response.getFirstHeader(HTTP.CONTENT_LEN);
if (contentLength != null) {
final long contentLengthValue = Long.parseLong(contentLength.getValue());
if (contentLengthValue > this.maxObjectSizeBytes) {
return false;
}
}
final Header[] ageHeaders = response.getHeaders(HeaderConstants.AGE);
if (ageHeaders.length > 1) {
return false;
}
final Header[] expiresHeaders = response.getHeaders(HeaderConstants.EXPIRES);
if (expiresHeaders.length > 1) {
return false;
}
final Header[] dateHeaders = response.getHeaders(HTTP.DATE_HEADER);
if (dateHeaders.length != 1) {
return false;
}
final Date date = DateUtils.parseDate(dateHeaders[0].getValue());
if (date == null) {
return false;
}
for (final Header varyHdr : response.getHeaders(HeaderConstants.VARY)) {
for (final HeaderElement elem : varyHdr.getElements()) {
if ("*".equals(elem.getName())) {
return false;
}
}
}
if (isExplicitlyNonCacheable(response)) {
return false;
}
return (cacheable || isExplicitlyCacheable(response));
}
private boolean unknownStatusCode(final 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(final HttpResponse response) {
final Header[] cacheControlHeaders = response.getHeaders(HeaderConstants.CACHE_CONTROL);
for (final Header header : cacheControlHeaders) {
for (final 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(final HttpMessage msg, final String[] params) {
final Header[] cacheControlHeaders = msg.getHeaders(HeaderConstants.CACHE_CONTROL);
for (final Header header : cacheControlHeaders) {
for (final HeaderElement elem : header.getElements()) {
for (final String param : params) {
if (param.equalsIgnoreCase(elem.getName())) {
return true;
}
}
}
}
return false;
}
protected boolean isExplicitlyCacheable(final HttpResponse response) {
if (response.getFirstHeader(HeaderConstants.EXPIRES) != null) {
return true;
}
final 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 {@code true} if response is cacheable
*/
public boolean isResponseCacheable(final HttpRequest request, final HttpResponse response) {
if (requestProtocolGreaterThanAccepted(request)) {
log.debug("Response was not cacheable.");
return false;
}
final String[] uncacheableRequestDirectives = { HeaderConstants.CACHE_CONTROL_NO_STORE };
if (hasCacheControlParameterFrom(request,uncacheableRequestDirectives)) {
return false;
}
if (request.getRequestLine().getUri().contains("?")) {
if (neverCache1_0ResponsesWithQueryString && from1_0Origin(response)) {
log.debug("Response was not cacheable as it had a query string.");
return false;
} else if (!isExplicitlyCacheable(response)) {
log.debug("Response was not cacheable as it is missing explicit caching headers.");
return false;
}
}
if (expiresHeaderLessOrEqualToDateHeaderAndNoCacheControl(response)) {
return false;
}
if (sharedCache) {
final Header[] authNHeaders = request.getHeaders(HeaderConstants.AUTHORIZATION);
if (authNHeaders != null && authNHeaders.length > 0
&& !hasCacheControlParameterFrom(response, AUTH_CACHEABLE_PARAMS)) {
return false;
}
}
final String method = request.getRequestLine().getMethod();
return isResponseCacheable(method, response);
}
private boolean expiresHeaderLessOrEqualToDateHeaderAndNoCacheControl(
final HttpResponse response) {
if (response.getFirstHeader(HeaderConstants.CACHE_CONTROL) != null) {
return false;
}
final Header expiresHdr = response.getFirstHeader(HeaderConstants.EXPIRES);
final Header dateHdr = response.getFirstHeader(HTTP.DATE_HEADER);
if (expiresHdr == null || dateHdr == null) {
return false;
}
final Date expires = DateUtils.parseDate(expiresHdr.getValue());
final Date date = DateUtils.parseDate(dateHdr.getValue());
if (expires == null || date == null) {
return false;
}
return expires.equals(date) || expires.before(date);
}
private boolean from1_0Origin(final HttpResponse response) {
final Header via = response.getFirstHeader(HeaderConstants.VIA);
if (via != null) {
for(final HeaderElement elt : via.getElements()) {
final 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(final HttpRequest req) {
return req.getProtocolVersion().compareToVersion(HttpVersion.HTTP_1_1) > 0;
}
}