com.zachklipp.jfavicon.FaviconLoader.java Source code

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Here is the source code for com.zachklipp.jfavicon.FaviconLoader.java

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/*
Copyright 2014 Zach Klippenstein
    
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.zachklipp.jfavicon;

import com.squareup.okhttp.OkHttpClient;
import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;
import org.jsoup.select.Elements;

import java.net.MalformedURLException;
import java.net.URL;
import java.util.HashSet;
import java.util.Set;
import java.util.concurrent.Executor;

import static com.zachklipp.jfavicon.Utils.checkNotNull;

/**
 * Load favicons for a {@link Source}. If the source's HTML is not specified, it will be loaded.
 * If the html contains favicon links, the domain favicons will be omitted.
 * Can be configured to run network operations on a different thread by passing in different {@link Executor}s.
 */
public class FaviconLoader {

    private static final String ICON_LINK_SELECTOR = "link[rel~=^(.*\\s|)icon(|\\s.*)$]";

    /**
     * Passed the results of {@code getFavicons}.
     */
    public static interface FaviconCallback {
        void onFaviconsLoaded(Set<URL> favicons);
    }

    private HttpClient client;
    private Executor worker;
    private Executor responder;

    public FaviconLoader() {
        client = new OkHttpHttpClient(new OkHttpClient());
        worker = SynchronousExecutor.getInstance();
        responder = SynchronousExecutor.getInstance();
    }

    public FaviconLoader setClient(HttpClient client) {
        this.client = checkNotNull(client, "client");
        return this;
    }

    public FaviconLoader setWorker(Executor worker) {
        this.worker = checkNotNull(worker, "worker");
        return this;
    }

    public FaviconLoader setResponder(Executor responder) {
        this.responder = checkNotNull(responder, "responder");
        return this;
    }

    public void getFavicons(String url, FaviconCallback callback) {
        Source source = Source.fromUrl(url).build();
        getFavicons(source, callback);
    }

    public void getFavicons(String url, String body, FaviconCallback callback) {
        Source source = Source.fromUrl(url).withBody(body).build();
        getFavicons(source, callback);
    }

    public void getFavicons(URL url, FaviconCallback callback) {
        Source source = Source.fromUrl(url).build();
        getFavicons(source, callback);
    }

    public void getFavicons(URL url, String body, FaviconCallback callback) {
        Source source = Source.fromUrl(url).withBody(body).build();
        getFavicons(source, callback);
    }

    void getFavicons(Source source, FaviconCallback callback) {
        worker.execute(new Worker(client, responder, source, callback));
    }

    private static class Worker implements Runnable {
        private final HttpClient client;
        private final Executor responder;
        private final Source source;
        private final FaviconCallback callback;

        public Worker(HttpClient client, Executor responder, Source source, FaviconCallback callback) {
            this.client = client;
            this.responder = responder;
            this.source = source;
            this.callback = callback;
        }

        @Override
        public void run() {
            final Set<URL> favicons = new HashSet<>();
            final String html = getOrLoadBody(source);

            getFaviconsFromHtml(html, favicons);

            if (favicons.isEmpty()) {
                getDomainFavicons(source, favicons);
            }

            responder.execute(new Runnable() {
                @Override
                public void run() {
                    callback.onFaviconsLoaded(favicons);
                }
            });
        }

        /**
         * Extract all the elements from an HTML document that define a link to a favicon resource.
         * Ignores all parsing-related exceptions.
         */
        private void getFaviconsFromHtml(final String html, final Set<URL> favicons) {
            // Passing the base URI allows JSoup to resolve URLs for us automatically.
            final String baseUri = source.getUrl().toString();
            final Document document = Jsoup.parse(html, baseUri);
            final Elements faviconLinks = document.head().select(ICON_LINK_SELECTOR);

            for (Element elem : faviconLinks) {
                final String href = elem.absUrl("href");

                try {
                    favicons.add(new URL(href));
                } catch (MalformedURLException e) {
                    // Ignore errors parsing individual link elements.
                }
            }
        }

        /**
         * Finds all valid domain favicons for a URL.
         */
        private void getDomainFavicons(final Source source, final Set<URL> favicons) {
            for (URL favicon : source.getDomainFavicons()) {
                if (client.doesResourceExist(favicon)) {
                    favicons.add(favicon);
                }
            }
        }

        /**
         * Returns the {@link Source}'s HTML if specified, else gets the body from the network.
         */
        private String getOrLoadBody(Source source) {
            String html = source.getBody();
            if (html == null) {
                html = client.tryLoadBody(source.getUrl());
            }
            return html;
        }
    }
}