ImageResponseCache.java

/**
 * Copyright 2010-present Facebook.
 *
 * 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.facebook.widget;

import android.content.Context;
import android.util.Log;
import com.facebook.internal.Logger;
import com.facebook.LoggingBehavior;
import com.facebook.internal.Utility;
import com.facebook.internal.FileLruCache;

import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

class ImageResponseCache {
    static final String TAG = ImageResponseCache.class.getSimpleName();

    private volatile static FileLruCache imageCache;

    synchronized static FileLruCache getCache(Context context) throws IOException{
        if (imageCache == null) {
            imageCache = new FileLruCache(context.getApplicationContext(), TAG, new FileLruCache.Limits());
        }
        return imageCache;
    }

    // Get stream from cache, or return null if the image is not cached.
    // Does not throw if there was an error.
    static InputStream getCachedImageStream(URL url, Context context) {
        InputStream imageStream = null;
        if (url != null) {
            if (isCDNURL(url)) {
                try {
                    FileLruCache cache = getCache(context);
                    imageStream = cache.get(url.toString());
                } catch (IOException e) {
                    Logger.log(LoggingBehavior.CACHE, Log.WARN, TAG, e.toString());
                }
            }
        }

        return imageStream;
    }

    static InputStream interceptAndCacheImageStream(Context context, HttpURLConnection connection) throws IOException {
        InputStream stream = null;
        if (connection.getResponseCode() == HttpURLConnection.HTTP_OK) {
            URL url = connection.getURL();
            stream = connection.getInputStream(); // Default stream in case caching fails
            if (isCDNURL(url)) {
                try {
                    FileLruCache cache = getCache(context);

                    // Wrap stream with a caching stream
                    stream = cache.interceptAndPut(
                            url.toString(),
                            new BufferedHttpInputStream(stream, connection));
                } catch (IOException e) {
                    // Caching is best effort
                }
            }
        }
        return stream;
    }

   private static boolean isCDNURL(URL url) {
        if (url != null) {
            String uriHost = url.getHost();

            if (uriHost.endsWith("fbcdn.net")) {
                return true;
            }

            if (uriHost.startsWith("fbcdn") && uriHost.endsWith("akamaihd.net")) {
                return true;
            }
        }

        return false;
    }

    private static class BufferedHttpInputStream extends BufferedInputStream {
        HttpURLConnection connection;
        BufferedHttpInputStream(InputStream stream, HttpURLConnection connection) {
            super(stream, Utility.DEFAULT_STREAM_BUFFER_SIZE);
            this.connection = connection;
        }

        @Override
        public void close() throws IOException {
            super.close();
            Utility.disconnectQuietly(connection);
        }
    }
}