Android Open Source - android_rss_reader Async Http Downloader

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License

The source code is released under:
Apache License
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Java Source Code

/***********************************************************************************************************************
 * ==========================================
 */*w  w  w .  j av  a 2  s  .c  o m*/
 * Copyright (C) 2013 by Paul Oremland
 * http://www.linkedin.com/in/pauloremland
 * https://github.com/poremland
 *
 ***********************************************************************************************************************
 *
 * 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 net.oremland.rss.reader.helpers;

import android.os.AsyncTask;

import java.io.*;
import java.net.*;
import java.util.*;

public class AsyncHttpDownloader
  extends
    AsyncTask<String, Integer, byte[]>
{
  public interface OnDownloadListener
  {
    void onProgress(int progress);
    void onComplete(byte[] result);
    void onError(Exception exception);
  }

  private OnDownloadListener listener = null;
  private Exception exception = null;
  private static final int BUFFER_SIZE = 4096;
  private static final int TIMEOUT = 30000;
  private Map<String, String> parameters = new HashMap<String, String>();

  public void setOnDownloadListener(OnDownloadListener listener)
  {
    this.listener = listener;
  }

  public void addRequestParameter(String key, String value)
  {
    this.parameters.put(key, value);
  }

  @Override
  protected byte[] doInBackground(String... urls)
  {
    if(this.listener != null && urls != null)
    {
      try
      {
        return download(urls[0]);
      }
      catch(Exception e)
      {
        this.exception = e;
      }
    }
    return new byte[0];
  }

  @Override
  protected void onProgressUpdate(Integer... progress)
  {
    this.listener.onProgress(progress[0]);
  }

  @Override
  protected void onPostExecute(byte[] result)
  {
    if(exception != null)
    {
      this.listener.onError(this.exception);
      return;
    }
    this.listener.onComplete(result);
  }

  private byte[] download(String requestUrl)
    throws IOException
  {
    HttpURLConnection connection = this.createHttpConnection(requestUrl);

    try
    {
      return this.getBytesFromConnection(connection);
    }
    finally
    {
      connection.disconnect();
    }
  }

  private HttpURLConnection createHttpConnection(String requestUrl)
    throws IOException
  {
    URL url = new URL(requestUrl);
    HttpURLConnection connection = (HttpURLConnection)url.openConnection();

    this.addParametersToConnection(connection);

    return connection;
  }

  private void addParametersToConnection(HttpURLConnection connection)
  {
    connection.setConnectTimeout(TIMEOUT);
    connection.setReadTimeout(TIMEOUT);

    if (this.parameters == null)
    {
      return;
    }

    for (String key : this.parameters.keySet())
    {
      String value = this.parameters.get(key);

      connection.addRequestProperty(key, value);
    }
  }

  private byte[] getBytesFromConnection(HttpURLConnection connection)
    throws IOException
  {
    ByteArrayOutputStream data = new ByteArrayOutputStream();
    InputStream stream = connection.getInputStream();

    byte[] buffer = new byte[BUFFER_SIZE];
    int length;

    while ((length = stream.read(buffer)) > 0)
    {
      data.write(buffer, 0, length);
    }
    stream.close();

    return data.toByteArray();
  }
}
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