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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
* .
*
*/
package org.apache.http.impl.client.cache;
import java.io.UnsupportedEncodingException;
import java.net.MalformedURLException;
import java.net.URI;
import java.net.URL;
import java.net.URLEncoder;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import org.apache.http.Consts;
import org.apache.http.Header;
import org.apache.http.HeaderElement;
import org.apache.http.HttpHost;
import org.apache.http.HttpRequest;
import org.apache.http.annotation.Immutable;
import org.apache.http.client.cache.HeaderConstants;
import org.apache.http.client.cache.HttpCacheEntry;
import org.apache.http.client.utils.URIUtils;
/**
* @since 4.1
*/
@Immutable
class CacheKeyGenerator {
private static final URI BASE_URI = URI.create("http://example.com/");
/**
* For a given {@link HttpHost} and {@link HttpRequest} get a URI from the
* pair that I can use as an identifier KEY into my HttpCache
*
* @param host The host for this request
* @param req the {@link HttpRequest}
* @return String the extracted URI
*/
public String getURI(final HttpHost host, final HttpRequest req) {
if (isRelativeRequest(req)) {
return canonicalizeUri(String.format("%s%s", host.toString(), req.getRequestLine().getUri()));
}
return canonicalizeUri(req.getRequestLine().getUri());
}
public String canonicalizeUri(final String uri) {
try {
final URI normalized = URIUtils.resolve(BASE_URI, uri);
final URL u = new URL(normalized.toASCIIString());
final String protocol = u.getProtocol();
final String hostname = u.getHost();
final int port = canonicalizePort(u.getPort(), protocol);
final String path = u.getPath();
final String query = u.getQuery();
final String file = (query != null) ? (path + "?" + query) : path;
final URL out = new URL(protocol, hostname, port, file);
return out.toString();
} catch (final IllegalArgumentException e) {
return uri;
} catch (final MalformedURLException e) {
return uri;
}
}
private int canonicalizePort(final int port, final String protocol) {
if (port == -1 && "http".equalsIgnoreCase(protocol)) {
return 80;
} else if (port == -1 && "https".equalsIgnoreCase(protocol)) {
return 443;
}
return port;
}
private boolean isRelativeRequest(final HttpRequest req) {
final String requestUri = req.getRequestLine().getUri();
return ("*".equals(requestUri) || requestUri.startsWith("/"));
}
protected String getFullHeaderValue(final Header[] headers) {
if (headers == null) {
return "";
}
final StringBuilder buf = new StringBuilder("");
boolean first = true;
for (final Header hdr : headers) {
if (!first) {
buf.append(", ");
}
buf.append(hdr.getValue().trim());
first = false;
}
return buf.toString();
}
/**
* For a given {@link HttpHost} and {@link HttpRequest} if the request has a
* VARY header - I need to get an additional URI from the pair of host and
* request so that I can also store the variant into my HttpCache.
*
* @param host The host for this request
* @param req the {@link HttpRequest}
* @param entry the parent entry used to track the variants
* @return String the extracted variant URI
*/
public String getVariantURI(final HttpHost host, final HttpRequest req, final HttpCacheEntry entry) {
if (!entry.hasVariants()) {
return getURI(host, req);
}
return getVariantKey(req, entry) + getURI(host, req);
}
/**
* Compute a "variant key" from the headers of a given request that are
* covered by the Vary header of a given cache entry. Any request whose
* varying headers match those of this request should have the same
* variant key.
* @param req originating request
* @param entry cache entry in question that has variants
* @return a {@code String} variant key
*/
public String getVariantKey(final HttpRequest req, final HttpCacheEntry entry) {
final List variantHeaderNames = new ArrayList();
for (final Header varyHdr : entry.getHeaders(HeaderConstants.VARY)) {
for (final HeaderElement elt : varyHdr.getElements()) {
variantHeaderNames.add(elt.getName());
}
}
Collections.sort(variantHeaderNames);
StringBuilder buf;
try {
buf = new StringBuilder("{");
boolean first = true;
for (final String headerName : variantHeaderNames) {
if (!first) {
buf.append("&");
}
buf.append(URLEncoder.encode(headerName, Consts.UTF_8.name()));
buf.append("=");
buf.append(URLEncoder.encode(getFullHeaderValue(req.getHeaders(headerName)),
Consts.UTF_8.name()));
first = false;
}
buf.append("}");
} catch (final UnsupportedEncodingException uee) {
throw new RuntimeException("couldn't encode to UTF-8", uee);
}
return buf.toString();
}
}