| /* |
| * Copyright (C) 2011 The Android Open Source Project |
| * |
| * Licensed 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. |
| */ |
| |
| package com.android.volley.toolbox; |
| |
| import com.android.volley.Cache; |
| import com.android.volley.NetworkResponse; |
| |
| import org.apache.http.impl.cookie.DateParseException; |
| import org.apache.http.impl.cookie.DateUtils; |
| import org.apache.http.protocol.HTTP; |
| |
| import java.util.Map; |
| |
| /** |
| * Utility methods for parsing HTTP headers. |
| */ |
| public class HttpHeaderParser { |
| |
| /** |
| * Extracts a {@link Cache.Entry} from a {@link NetworkResponse}. |
| * |
| * @param response The network response to parse headers from |
| * @return a cache entry for the given response, or null if the response is not cacheable. |
| */ |
| public static Cache.Entry parseCacheHeaders(NetworkResponse response) { |
| long now = System.currentTimeMillis(); |
| |
| Map<String, String> headers = response.headers; |
| |
| long serverDate = 0; |
| long lastModified = 0; |
| long serverExpires = 0; |
| long softExpire = 0; |
| long finalExpire = 0; |
| long maxAge = 0; |
| long staleWhileRevalidate = 0; |
| boolean hasCacheControl = false; |
| boolean mustRevalidate = false; |
| |
| String serverEtag = null; |
| String headerValue; |
| |
| headerValue = headers.get("Date"); |
| if (headerValue != null) { |
| serverDate = parseDateAsEpoch(headerValue); |
| } |
| |
| headerValue = headers.get("Cache-Control"); |
| if (headerValue != null) { |
| hasCacheControl = true; |
| String[] tokens = headerValue.split(","); |
| for (int i = 0; i < tokens.length; i++) { |
| String token = tokens[i].trim(); |
| if (token.equals("no-cache") || token.equals("no-store")) { |
| return null; |
| } else if (token.startsWith("max-age=")) { |
| try { |
| maxAge = Long.parseLong(token.substring(8)); |
| } catch (Exception e) { |
| } |
| } else if (token.startsWith("stale-while-revalidate=")) { |
| try { |
| staleWhileRevalidate = Long.parseLong(token.substring(23)); |
| } catch (Exception e) { |
| } |
| } else if (token.equals("must-revalidate") || token.equals("proxy-revalidate")) { |
| mustRevalidate = true; |
| } |
| } |
| } |
| |
| headerValue = headers.get("Expires"); |
| if (headerValue != null) { |
| serverExpires = parseDateAsEpoch(headerValue); |
| } |
| |
| headerValue = headers.get("Last-Modified"); |
| if (headerValue != null) { |
| lastModified = parseDateAsEpoch(headerValue); |
| } |
| |
| serverEtag = headers.get("ETag"); |
| |
| // Cache-Control takes precedence over an Expires header, even if both exist and Expires |
| // is more restrictive. |
| if (hasCacheControl) { |
| softExpire = now + maxAge * 1000; |
| finalExpire = mustRevalidate |
| ? softExpire |
| : softExpire + staleWhileRevalidate * 1000; |
| } else if (serverDate > 0 && serverExpires >= serverDate) { |
| // Default semantic for Expire header in HTTP specification is softExpire. |
| softExpire = now + (serverExpires - serverDate); |
| finalExpire = softExpire; |
| } |
| |
| Cache.Entry entry = new Cache.Entry(); |
| entry.data = response.data; |
| entry.etag = serverEtag; |
| entry.softTtl = softExpire; |
| entry.ttl = finalExpire; |
| entry.serverDate = serverDate; |
| entry.lastModified = lastModified; |
| entry.responseHeaders = headers; |
| |
| return entry; |
| } |
| |
| /** |
| * Parse date in RFC1123 format, and return its value as epoch |
| */ |
| public static long parseDateAsEpoch(String dateStr) { |
| try { |
| // Parse date in RFC1123 format if this header contains one |
| return DateUtils.parseDate(dateStr).getTime(); |
| } catch (DateParseException e) { |
| // Date in invalid format, fallback to 0 |
| return 0; |
| } |
| } |
| |
| /** |
| * Retrieve a charset from headers |
| * |
| * @param headers An {@link java.util.Map} of headers |
| * @param defaultCharset Charset to return if none can be found |
| * @return Returns the charset specified in the Content-Type of this header, |
| * or the defaultCharset if none can be found. |
| */ |
| public static String parseCharset(Map<String, String> headers, String defaultCharset) { |
| String contentType = headers.get(HTTP.CONTENT_TYPE); |
| if (contentType != null) { |
| String[] params = contentType.split(";"); |
| for (int i = 1; i < params.length; i++) { |
| String[] pair = params[i].trim().split("="); |
| if (pair.length == 2) { |
| if (pair[0].equals("charset")) { |
| return pair[1]; |
| } |
| } |
| } |
| } |
| |
| return defaultCharset; |
| } |
| |
| /** |
| * Returns the charset specified in the Content-Type of this header, |
| * or the HTTP default (ISO-8859-1) if none can be found. |
| */ |
| public static String parseCharset(Map<String, String> headers) { |
| return parseCharset(headers, HTTP.DEFAULT_CONTENT_CHARSET); |
| } |
| } |