Java RequestWrapper.resetHeaders方法代码示例

import org.apache.http.impl.client.RequestWrapper; //导入方法依赖的package包/类
/**
 * 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
 * @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;

}
 

import org.apache.http.impl.client.RequestWrapper; //导入方法依赖的package包/类
/**
 * When a {@link HttpCacheEntry} does not exist for a specific
 * {@link HttpRequest} we attempt to see if an existing
 * {@link HttpCacheEntry} is appropriate by building a conditional
 * {@link HttpRequest} using the variants' ETag values. If no such values
 * exist, the request is unmodified
 * 
 * @param request
 *            the original request from the caller
 * @param cacheEntry
 *            the entry that needs to be revalidated
 * @return the wrapped request
 * @throws ProtocolException
 *             when I am unable to build a new origin request.
 */
public HttpRequest buildConditionalRequestFromVariants(HttpRequest request,
		Set<HttpCacheEntry> variantEntries) throws ProtocolException {
	RequestWrapper wrapperRequest = new RequestWrapper(request);
	wrapperRequest.resetHeaders();

	// we do not support partial content so all etags are used
	StringBuilder etags = new StringBuilder();
	boolean first = true;
	for (HttpCacheEntry entry : variantEntries) {
		Header etagHeader = entry.getFirstHeader(HeaderConstants.ETAG);
		if (etagHeader != null) {
			if (first) {
				etags.append(etagHeader.getValue());
				first = false;
			} else {
				etags.append(",").append(etagHeader.getValue());
			}
		}
	}
	// if first is still true than no variants had a cache entry, return
	// unmodified wrapped request
	if (first) {
		return wrapperRequest;
	}

	wrapperRequest.setHeader(HeaderConstants.IF_NONE_MATCH,
			etags.toString());

	return wrapperRequest;
}
 

import org.apache.http.impl.client.RequestWrapper; //导入方法依赖的package包/类
/**
 * 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
 * @throws ProtocolException
 */
public HttpRequest buildUnconditionalRequest(HttpRequest request,
		HttpCacheEntry entry) throws ProtocolException {
	RequestWrapper wrapped = new RequestWrapper(request);
	wrapped.resetHeaders();
	wrapped.addHeader("Cache-Control", "no-cache");
	wrapped.addHeader("Pragma", "no-cache");
	wrapped.removeHeaders("If-Range");
	wrapped.removeHeaders("If-Match");
	wrapped.removeHeaders("If-None-Match");
	wrapped.removeHeaders("If-Unmodified-Since");
	wrapped.removeHeaders("If-Modified-Since");
	return wrapped;
}