com.blork.anpod.util.SyncUtils.java Source code

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Here is the source code for com.blork.anpod.util.SyncUtils.java

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/*
 * Copyright 2011 Google Inc.
 *
 * 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.blork.anpod.util;

import java.io.IOException;
import java.io.InputStream;
import java.util.zip.GZIPInputStream;

import org.apache.http.Header;
import org.apache.http.HeaderElement;
import org.apache.http.HttpEntity;
import org.apache.http.HttpRequest;
import org.apache.http.HttpRequestInterceptor;
import org.apache.http.HttpResponse;
import org.apache.http.HttpResponseInterceptor;
import org.apache.http.client.HttpClient;
import org.apache.http.entity.HttpEntityWrapper;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.params.BasicHttpParams;
import org.apache.http.params.HttpConnectionParams;
import org.apache.http.params.HttpParams;
import org.apache.http.params.HttpProtocolParams;
import org.apache.http.protocol.HttpContext;

import android.app.Service;
import android.content.Context;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.content.pm.PackageManager.NameNotFoundException;
import android.content.res.Resources;
import android.text.format.DateUtils;

// TODO: Auto-generated Javadoc
/**
 * Background {@link Service} that synchronizes data living in.
 *
 * {@link ScheduleProvider}. Reads data from both local {@link Resources} and
 * from remote sources, such as a spreadsheet.
 */
class SyncUtils {

    /** The Constant SECOND_IN_MILLIS. */
    private static final int SECOND_IN_MILLIS = (int) DateUtils.SECOND_IN_MILLIS;

    /** The Constant HEADER_ACCEPT_ENCODING. */
    private static final String HEADER_ACCEPT_ENCODING = "Accept-Encoding";

    /** The Constant ENCODING_GZIP. */
    private static final String ENCODING_GZIP = "gzip";

    /**
     * Generate and return a {@link HttpClient} configured for general use,
     * including setting an application-specific user-agent string.
     *
     * @param context the context
     * @return the http client
     */
    static HttpClient getHttpClient(Context context) {
        final HttpParams params = new BasicHttpParams();

        // Use generous timeouts for slow mobile networks
        HttpConnectionParams.setConnectionTimeout(params, 20 * SECOND_IN_MILLIS);
        HttpConnectionParams.setSoTimeout(params, 20 * SECOND_IN_MILLIS);

        HttpConnectionParams.setSocketBufferSize(params, 8192);
        HttpProtocolParams.setUserAgent(params, buildUserAgent(context));

        final DefaultHttpClient client = new DefaultHttpClient(params);

        client.addRequestInterceptor(new HttpRequestInterceptor() {
            public void process(HttpRequest request, HttpContext context) {
                // Add header to accept gzip content
                if (!request.containsHeader(HEADER_ACCEPT_ENCODING)) {
                    request.addHeader(HEADER_ACCEPT_ENCODING, ENCODING_GZIP);
                }
            }
        });

        client.addResponseInterceptor(new HttpResponseInterceptor() {
            public void process(HttpResponse response, HttpContext context) {
                // Inflate any responses compressed with gzip
                final HttpEntity entity = response.getEntity();
                final Header encoding = entity.getContentEncoding();
                if (encoding != null) {
                    for (HeaderElement element : encoding.getElements()) {
                        if (element.getName().equalsIgnoreCase(ENCODING_GZIP)) {
                            response.setEntity(new InflatingEntity(response.getEntity()));
                            break;
                        }
                    }
                }
            }
        });

        return client;
    }

    /**
     * Build and return a user-agent string that can identify this application
     * to remote servers. Contains the package name and version code.
     *
     * @param context the context
     * @return the string
     */
    private static String buildUserAgent(Context context) {
        try {
            final PackageManager manager = context.getPackageManager();
            final PackageInfo info = manager.getPackageInfo(context.getPackageName(), 0);

            // Some APIs require "(gzip)" in the user-agent string.
            return info.packageName + "/" + info.versionName + " (" + info.versionCode + ") (gzip)";
        } catch (NameNotFoundException e) {
            return null;
        }
    }

    /**
     * Simple {@link HttpEntityWrapper} that inflates the wrapped.
     *
     * {@link HttpEntity} by passing it through {@link GZIPInputStream}.
     */
    private static class InflatingEntity extends HttpEntityWrapper {

        /**
         * Instantiates a new inflating entity.
         *
         * @param wrapped the wrapped
         */
        public InflatingEntity(HttpEntity wrapped) {
            super(wrapped);
        }

        /* (non-Javadoc)
         * @see org.apache.http.entity.HttpEntityWrapper#getContent()
         */
        @Override
        public InputStream getContent() throws IOException {
            return new GZIPInputStream(wrappedEntity.getContent());
        }

        /* (non-Javadoc)
         * @see org.apache.http.entity.HttpEntityWrapper#getContentLength()
         */
        @Override
        public long getContentLength() {
            return -1;
        }
    }
}