Example usage for org.apache.http.client.cache HeaderConstants CACHE_CONTROL_PROXY_REVALIDATE

Introduction

In this page you can find the example usage for org.apache.http.client.cache HeaderConstants CACHE_CONTROL_PROXY_REVALIDATE.

Prototype

String CACHE_CONTROL_PROXY_REVALIDATE

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Usage

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//from w  w  w  . java 2 s . c o  m
 * @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;

}

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