cn.dooland.net.NeverOutDateHttpHeaderParser.java Source code

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Here is the source code for cn.dooland.net.NeverOutDateHttpHeaderParser.java

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/*
 * 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 cn.dooland.net;

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. with no outdate
 */
public class NeverOutDateHttpHeaderParser {

    /**
     * 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) {

        Map<String, String> headers = response.headers;

        long serverDate = 0;
        long lastModified = 0;

        String serverEtag = null;
        String headerValue;

        headerValue = headers.get("Date");
        if (headerValue != null) {
            serverDate = parseDateAsEpoch(headerValue);
        }

        headerValue = headers.get("Last-Modified");
        if (headerValue != null) {
            lastModified = parseDateAsEpoch(headerValue);
        }

        serverEtag = headers.get("ETag");

        Cache.Entry entry = new Cache.Entry();
        entry.data = response.data;
        entry.etag = serverEtag;
        entry.softTtl = Long.MAX_VALUE;
        entry.ttl = Long.MAX_VALUE;
        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);
    }
}