Subversion Repositories SmartDukaan

/**

 * 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.internal;

import android.content.Context;

import android.util.Log;

import com.facebook.LoggingBehavior;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.io.OutputStream;

import java.net.URI;

import java.net.URISyntaxException;

class UrlRedirectCache {

    static final String TAG = UrlRedirectCache.class.getSimpleName();

    private static final String REDIRECT_CONTENT_TAG = TAG + "_Redirect";

    private volatile static FileLruCache urlRedirectCache;

    synchronized static FileLruCache getCache(Context context) throws IOException{

        if (urlRedirectCache == null) {

            urlRedirectCache = new FileLruCache(context.getApplicationContext(), TAG, new FileLruCache.Limits());

        }

        return urlRedirectCache;

    }

    static URI getRedirectedUri(Context context, URI uri) {

        if (uri == null) {

            return null;

        }

        String uriString = uri.toString();

        InputStreamReader reader = null;

        try {

            InputStream stream;

            FileLruCache cache = getCache(context);

            boolean redirectExists = false;

            while ((stream = cache.get(uriString, REDIRECT_CONTENT_TAG)) != null) {

                redirectExists = true;

                // Get the redirected url

                reader = new InputStreamReader(stream);

                char[] buffer = new char[128];

                int bufferLength;

                StringBuilder urlBuilder = new StringBuilder();

                while ((bufferLength = reader.read(buffer, 0, buffer.length)) > 0) {

                    urlBuilder.append(buffer, 0, bufferLength);

                }

                Utility.closeQuietly(reader);

                // Iterate to the next url in the redirection

                uriString = urlBuilder.toString();

            }

            if (redirectExists) {

                return new URI(uriString);

            }

        } catch (URISyntaxException e) {

            // caching is best effort, so ignore the exception

        } catch (IOException ioe) {

        } finally {

            Utility.closeQuietly(reader);

        }

        return null;

    }

    static void cacheUriRedirect(Context context, URI fromUri, URI toUri) {

        if (fromUri == null || toUri == null) {

            return;

        }

        OutputStream redirectStream = null;

        try {

            FileLruCache cache = getCache(context);

            redirectStream = cache.openPutStream(fromUri.toString(), REDIRECT_CONTENT_TAG);

            redirectStream.write(toUri.toString().getBytes());

        } catch (IOException e) {

            // Caching is best effort

        } finally {

            Utility.closeQuietly(redirectStream);

        }

    }

    static void clearCache(Context context) {

        try {

            getCache(context).clearCache();

        } catch (IOException e) {

            Logger.log(LoggingBehavior.CACHE, Log.WARN, TAG, "clearCache failed " + e.getMessage());

        }

    }

}