Downloader.java

package org.djd.busntrain.commons;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;
import org.djd.busntrain.commons.DownloadException.ERROR_CODE;

import android.util.Log;

public class Downloader {

  private static final String TAG = Downloader.class.getSimpleName();

  private Downloader() {
  }

  /**
   * DefaultHttpClient is thread safe. It is recommended that the same
   * instance of this class is reused for multiple request executions. When an
   * instance of DefaultHttpClient is no longer needed and is about to go out
   * of scope the connection manager associated with it must be shut down by
   * calling the ClientConnectionManager#shutdown() method.
   */
  private static final HttpClient HTTP_CLIENT = new DefaultHttpClient();

  public static String getAsString(String url) throws DownloadException {
    Log.d(TAG, url);
    HttpEntity httpEntity = makeHttpRequest(url).getEntity();
    try {
      return EntityUtils.toString(httpEntity);
    } catch (IllegalStateException e) {
      throw new DownloadException(ERROR_CODE.ENTITY_IS_NOT_REPEATABLE);
    } catch (IOException e) {
      throw new DownloadException(ERROR_CODE.STREAM_COULD_NOT_BE_CREATED);
    }


  }

  public static ArrayList<String> loadTextFileToArrayList(String url)
      throws DownloadException {
    Log.i(TAG, url);
    return readTextFileToArrayList(getInputStream(url), true);

  }

  /**
   * @param inputStream to Text File.
   * @param trim        if set true blank like or a line which has only white space(s)
   *                    will be ignored.
   * @return {@link ArrayList} contains text file contents.
   * @throws DownloadException
   */
  public static ArrayList<String> readTextFileToArrayList(
      InputStream inputStream, boolean trim) throws DownloadException {

    ArrayList<String> list = new ArrayList<String>();
    BufferedReader reader = null;

    try {
      reader = new BufferedReader(new InputStreamReader(inputStream));
      for (String line = null; null != (line = reader.readLine()); ) {
        if (trim) {
          if (line.trim().isEmpty()) {
            continue;
          }
          list.add(line);
        }
      }
    } catch (IOException e) {
      throw new DownloadException(ERROR_CODE.READ_FILE_ERROR);
    } finally {

      if (null != reader) {
        try {
          reader.close();
        } catch (IOException e) {
          reader = null;
        }
      }
    }
    return list;
  }

  private static InputStream getInputStream(String url)
      throws DownloadException {

    HttpEntity httpEntity = makeHttpRequest(url).getEntity();
    try {
      return httpEntity.getContent();
    } catch (IllegalStateException e) {
      throw new DownloadException(ERROR_CODE.ENTITY_IS_NOT_REPEATABLE);
    } catch (IOException e) {
      throw new DownloadException(ERROR_CODE.STREAM_COULD_NOT_BE_CREATED);
    }

  }

  private static HttpResponse makeHttpRequest(String url)
      throws DownloadException {
    HttpResponse httpResponse;

    HttpGet httpGet = createHttpGet(url);

    try {
      httpResponse = HTTP_CLIENT.execute(httpGet);
    } catch (ClientProtocolException e) {
      throw new DownloadException(ERROR_CODE.HTTP_PROTOCOL_ERROR);
    } catch (IOException e) {
      Log.e(TAG, "Check android.permission.INTERNET is available.");
      throw new DownloadException(
          ERROR_CODE.FAILED_CREATE_HTTP_CONNECTION);
    }
    return httpResponse;
  }

  private static HttpGet createHttpGet(String url) throws DownloadException {
    if (null == url) {
      throw new DownloadException(ERROR_CODE.EMPTY_URL);
    }
    HttpGet request = new HttpGet(url);
    return request;
  }

  /**
   * This method should be called open
   */
  public static void shutdown() {
    HTTP_CLIENT.getConnectionManager().shutdown();
  }
}