Java tutorial
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For more * information on the Apache Software Foundation, please see * <http://www.apache.org/>. * */ package org.apache.http.impl.client.cache; import java.io.IOException; import java.util.Date; import java.util.HashMap; import java.util.Map; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.http.Header; import org.apache.http.HttpHost; import org.apache.http.HttpRequest; import org.apache.http.HttpResponse; import org.apache.http.HttpStatus; import org.apache.http.HttpVersion; import org.apache.http.client.cache.HeaderConstants; import org.apache.http.client.cache.HttpCacheEntry; import org.apache.http.client.cache.HttpCacheStorage; import org.apache.http.client.cache.HttpCacheUpdateCallback; import org.apache.http.client.cache.HttpCacheUpdateException; import org.apache.http.client.cache.Resource; import org.apache.http.client.cache.ResourceFactory; import org.apache.http.entity.ByteArrayEntity; import org.apache.http.message.BasicHttpResponse; class BasicHttpCache implements HttpCache { private final CacheKeyGenerator uriExtractor; private final ResourceFactory resourceFactory; private final int maxObjectSizeBytes; private final CacheEntryUpdater cacheEntryUpdater; private final CachedHttpResponseGenerator responseGenerator; private final CacheInvalidator cacheInvalidator; private final HttpCacheStorage storage; private final Log log = LogFactory.getLog(getClass()); public BasicHttpCache(ResourceFactory resourceFactory, HttpCacheStorage storage, CacheConfig config) { this.resourceFactory = resourceFactory; this.uriExtractor = new CacheKeyGenerator(); this.cacheEntryUpdater = new CacheEntryUpdater(resourceFactory); this.maxObjectSizeBytes = config.getMaxObjectSizeBytes(); this.responseGenerator = new CachedHttpResponseGenerator(); this.storage = storage; this.cacheInvalidator = new CacheInvalidator(this.uriExtractor, this.storage); } public BasicHttpCache(CacheConfig config) { this(new HeapResourceFactory(), new BasicHttpCacheStorage(config), config); } public BasicHttpCache() { this(new CacheConfig()); } public void flushCacheEntriesFor(HttpHost host, HttpRequest request) throws IOException { String uri = uriExtractor.getURI(host, request); storage.removeEntry(uri); } public void flushInvalidatedCacheEntriesFor(HttpHost host, HttpRequest request, HttpResponse response) { cacheInvalidator.flushInvalidatedCacheEntries(host, request, response); } void storeInCache(HttpHost target, HttpRequest request, HttpCacheEntry entry) throws IOException { if (entry.hasVariants()) { storeVariantEntry(target, request, entry); } else { storeNonVariantEntry(target, request, entry); } } void storeNonVariantEntry(HttpHost target, HttpRequest req, HttpCacheEntry entry) throws IOException { String uri = uriExtractor.getURI(target, req); storage.putEntry(uri, entry); } void storeVariantEntry(final HttpHost target, final HttpRequest req, final HttpCacheEntry entry) throws IOException { final String parentURI = uriExtractor.getURI(target, req); final String variantURI = uriExtractor.getVariantURI(target, req, entry); storage.putEntry(variantURI, entry); HttpCacheUpdateCallback callback = new HttpCacheUpdateCallback() { public HttpCacheEntry update(HttpCacheEntry existing) throws IOException { return doGetUpdatedParentEntry(req.getRequestLine().getUri(), existing, entry, uriExtractor.getVariantKey(req, entry), variantURI); } }; try { storage.updateEntry(parentURI, callback); } catch (HttpCacheUpdateException e) { log.warn("Could not update key [" + parentURI + "]", e); } } public void reuseVariantEntryFor(HttpHost target, final HttpRequest req, final Variant variant) throws IOException { final String parentCacheKey = uriExtractor.getURI(target, req); final HttpCacheEntry entry = variant.getEntry(); final String variantKey = uriExtractor.getVariantKey(req, entry); final String variantCacheKey = variant.getCacheKey(); HttpCacheUpdateCallback callback = new HttpCacheUpdateCallback() { public HttpCacheEntry update(HttpCacheEntry existing) throws IOException { return doGetUpdatedParentEntry(req.getRequestLine().getUri(), existing, entry, variantKey, variantCacheKey); } }; try { storage.updateEntry(parentCacheKey, callback); } catch (HttpCacheUpdateException e) { log.warn("Could not update key [" + parentCacheKey + "]", e); } } boolean isIncompleteResponse(HttpResponse resp, Resource resource) { int status = resp.getStatusLine().getStatusCode(); if (status != HttpStatus.SC_OK && status != HttpStatus.SC_PARTIAL_CONTENT) { return false; } Header hdr = resp.getFirstHeader("Content-Length"); if (hdr == null) return false; int contentLength; try { contentLength = Integer.parseInt(hdr.getValue()); } catch (NumberFormatException nfe) { return false; } return (resource.length() < contentLength); } HttpResponse generateIncompleteResponseError(HttpResponse response, Resource resource) { int contentLength = Integer.parseInt(response.getFirstHeader("Content-Length").getValue()); HttpResponse error = new BasicHttpResponse(HttpVersion.HTTP_1_1, HttpStatus.SC_BAD_GATEWAY, "Bad Gateway"); error.setHeader("Content-Type", "text/plain;charset=UTF-8"); String msg = String.format( "Received incomplete response " + "with Content-Length %d but actual body length %d", contentLength, resource.length()); byte[] msgBytes = msg.getBytes(); error.setHeader("Content-Length", Integer.toString(msgBytes.length)); error.setEntity(new ByteArrayEntity(msgBytes)); return error; } HttpCacheEntry doGetUpdatedParentEntry(final String requestId, final HttpCacheEntry existing, final HttpCacheEntry entry, final String variantKey, final String variantCacheKey) throws IOException { HttpCacheEntry src = existing; if (src == null) { src = entry; } Resource resource = resourceFactory.copy(requestId, src.getResource()); Map<String, String> variantMap = new HashMap<String, String>(src.getVariantMap()); variantMap.put(variantKey, variantCacheKey); return new HttpCacheEntry(src.getRequestDate(), src.getResponseDate(), src.getStatusLine(), src.getAllHeaders(), resource, variantMap); } public HttpCacheEntry updateCacheEntry(HttpHost target, HttpRequest request, HttpCacheEntry stale, HttpResponse originResponse, Date requestSent, Date responseReceived) throws IOException { HttpCacheEntry updatedEntry = cacheEntryUpdater.updateCacheEntry(request.getRequestLine().getUri(), stale, requestSent, responseReceived, originResponse); storeInCache(target, request, updatedEntry); return updatedEntry; } public HttpCacheEntry updateVariantCacheEntry(HttpHost target, HttpRequest request, HttpCacheEntry stale, HttpResponse originResponse, Date requestSent, Date responseReceived, String cacheKey) throws IOException { HttpCacheEntry updatedEntry = cacheEntryUpdater.updateCacheEntry(request.getRequestLine().getUri(), stale, requestSent, responseReceived, originResponse); storage.putEntry(cacheKey, updatedEntry); return updatedEntry; } public HttpResponse cacheAndReturnResponse(HttpHost host, HttpRequest request, HttpResponse originResponse, Date requestSent, Date responseReceived) throws IOException { SizeLimitedResponseReader responseReader = getResponseReader(request, originResponse); responseReader.readResponse(); if (responseReader.isLimitReached()) { return responseReader.getReconstructedResponse(); } Resource resource = responseReader.getResource(); if (isIncompleteResponse(originResponse, resource)) { return generateIncompleteResponseError(originResponse, resource); } HttpCacheEntry entry = new HttpCacheEntry(requestSent, responseReceived, originResponse.getStatusLine(), originResponse.getAllHeaders(), resource); storeInCache(host, request, entry); return responseGenerator.generateResponse(entry); } SizeLimitedResponseReader getResponseReader(HttpRequest request, HttpResponse backEndResponse) { return new SizeLimitedResponseReader(resourceFactory, maxObjectSizeBytes, request, backEndResponse); } public HttpCacheEntry getCacheEntry(HttpHost host, HttpRequest request) throws IOException { HttpCacheEntry root = storage.getEntry(uriExtractor.getURI(host, request)); if (root == null) return null; if (!root.hasVariants()) return root; String variantCacheKey = root.getVariantMap().get(uriExtractor.getVariantKey(request, root)); if (variantCacheKey == null) return null; return storage.getEntry(variantCacheKey); } public void flushInvalidatedCacheEntriesFor(HttpHost host, HttpRequest request) throws IOException { cacheInvalidator.flushInvalidatedCacheEntries(host, request); } public Map<String, Variant> getVariantCacheEntriesWithEtags(HttpHost host, HttpRequest request) throws IOException { Map<String, Variant> variants = new HashMap<String, Variant>(); HttpCacheEntry root = storage.getEntry(uriExtractor.getURI(host, request)); if (root == null || !root.hasVariants()) return variants; for (Map.Entry<String, String> variant : root.getVariantMap().entrySet()) { String variantKey = variant.getKey(); String variantCacheKey = variant.getValue(); addVariantWithEtag(variantKey, variantCacheKey, variants); } return variants; } private void addVariantWithEtag(String variantKey, String variantCacheKey, Map<String, Variant> variants) throws IOException { HttpCacheEntry entry = storage.getEntry(variantCacheKey); if (entry == null) return; Header etagHeader = entry.getFirstHeader(HeaderConstants.ETAG); if (etagHeader == null) return; variants.put(etagHeader.getValue(), new Variant(variantKey, variantCacheKey, entry)); } }