List of usage examples for org.apache.http.client.cache HeaderConstants CACHE_CONTROL_MUST_REVALIDATE
String CACHE_CONTROL_MUST_REVALIDATE
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From source file:org.apache.http.impl.client.cache.ConditionalRequestBuilder.java
/** * When a {@link HttpCacheEntry} is stale but 'might' be used as a response * to an {@link HttpRequest} we will attempt to revalidate the entry with * the origin. Build the origin {@link HttpRequest} here and return it. * * @param request the original request from the caller * @param cacheEntry the entry that needs to be revalidated * @return the wrapped request/* w w w . jav a2 s.c om*/ * @throws ProtocolException when I am unable to build a new origin request. */ public HttpRequest buildConditionalRequest(HttpRequest request, HttpCacheEntry cacheEntry) throws ProtocolException { RequestWrapper wrapperRequest = new RequestWrapper(request); wrapperRequest.resetHeaders(); Header eTag = cacheEntry.getFirstHeader(HeaderConstants.ETAG); if (eTag != null) { wrapperRequest.setHeader(HeaderConstants.IF_NONE_MATCH, eTag.getValue()); } Header lastModified = cacheEntry.getFirstHeader(HeaderConstants.LAST_MODIFIED); if (lastModified != null) { wrapperRequest.setHeader(HeaderConstants.IF_MODIFIED_SINCE, lastModified.getValue()); } boolean mustRevalidate = false; for (Header h : cacheEntry.getHeaders(HeaderConstants.CACHE_CONTROL)) { for (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) { wrapperRequest.addHeader("Cache-Control", "max-age=0"); } return wrapperRequest; }