Android Open Source - cloudwave Local Storage Manager

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Back to project page cloudwave.

License

The source code is released under:

Apache License

Java Source Code

package com.luboganev.cloudwave.data;
//from  w  w w . ja  v a2 s  .  com
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.Random;

import android.content.Context;

import com.google.gson.FieldNamingPolicy;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.luboganev.cloudwave.LogUtils;

/**
 * The local storage manager is responsible for reading and writing all locally cached data
 */
public class LocalStorageManager {
  private static final String LOCAL_STORAGE_FILE_NAME="soundwave_storage_json.txt";
  private LocalStorage mLocalStorage;
  private final Gson mGson;
  private final Context mApplicationContext;
  
  private static final String SOUNDWAVE_FILE_PREFIX = "soundwave_";
  private static final String SOUNDWAVE_FILE_SUFFIX = ".png";
  private static final String SOUNDWAVE_FILES_DIR = "soundwaves";
  
  public LocalStorageManager(Context applicationContext) {
    mApplicationContext = applicationContext;
    mGson = new GsonBuilder().setFieldNamingPolicy(FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES).create();
  }
  
  /**
   * Checks for existing persisted local storage
   * 
   * @return
   *     Persisted local storage exists
   */
  public boolean hasSavedLocalStorage() {
    File storageFile = new File(mApplicationContext.getFilesDir(), LOCAL_STORAGE_FILE_NAME);
    return storageFile.exists();
  }

  /**
   * @return
   *     Loads a previously saved local storage from disk
   */
  public boolean loadFromFile() {
    FileInputStream fis = null;
    try {
      fis = mApplicationContext.openFileInput(LOCAL_STORAGE_FILE_NAME);
      String jsonString = readStreamAsString(fis);
      mLocalStorage = mGson.fromJson(jsonString, LocalStorage.class);
      return true;
    } catch (IOException x) {
      LogUtils.e(this, "Cannot read the file");
      return false;
    } finally {
      closeStreamSilently(fis);
    }
  }
  
  /**
   * Loads a default empty storage for the default artist
   */
  public void loadDefaultStorage() {
    mLocalStorage = new LocalStorage();
    mLocalStorage.artistUsername = "heedthesound";
    mLocalStorage.artistTracks = new ArrayList<Track>();
    mLocalStorage.currentTrackIndex = -1;
    mLocalStorage.nextRandomIndex = -1;
  }
  
  /**
   * Adds a new track object to the list of tracks
   * 
   * @param id
   *     Track id
   * @param title
   *     Track title
   * @param permalinkUrl
   *     Track permalink url
   * @param waveformUrl
   *     Track waveform url
   */
  public void addTrack(long id, String title, String permalinkUrl, String waveformUrl) {
    Track newTrack = new Track();
    newTrack.id = id;
    newTrack.title = title;
    newTrack.permalinkUrl = permalinkUrl;
    newTrack.waveformUrl = waveformUrl;
    mLocalStorage.artistTracks.add(newTrack);
  }
  
  /**
   * Picks a new random index from the tracks list as next track index
   */
  public void pickNewNextRandomTrack() {
    Random r = new Random(System.currentTimeMillis());
    mLocalStorage.nextRandomIndex = r.nextInt(mLocalStorage.artistTracks.size());
  }
  
  /**
   * @return
   *     The next track
   */
  public Track getNextTrack() {
    if(mLocalStorage.nextRandomIndex >= 0)
      return mLocalStorage.artistTracks.get(mLocalStorage.nextRandomIndex);
    else return null;
  }
  
  /**
   * @return
   *     The current track
   */
  public Track getCurrentTrack() {
    return mLocalStorage.artistTracks.get(mLocalStorage.currentTrackIndex);
  }
  
  /**
   * Picks the next track as the current track
   */
  public void setNextAsCurrentTrack() {
    mLocalStorage.currentTrackIndex = mLocalStorage.nextRandomIndex;
  }
  
  /**
   * @return
   *     String containing the artist's name
   */
  public String getArtistName() {
    return mLocalStorage.artistUsername;
  }
  
  /**
   * Persists the currently loaded {@link LocalStorage}
   */
  public void saveToFile() {
    String json = mGson.toJson(mLocalStorage);
    FileOutputStream fos = null;
    try {
      fos = mApplicationContext.openFileOutput(LOCAL_STORAGE_FILE_NAME, Context.MODE_PRIVATE);
      fos.write(json.getBytes());
    } catch (IOException x) {
      LogUtils.e(this, "Cannot create or write to file");
    } finally {
      closeStreamSilently(fos);
    }
  }

  /**
   * Helper method which reads all inputstream contents 
   * and writes them to an outputstream
   */
  private void copy(InputStream reader, OutputStream writer)
      throws IOException {
    byte byteArray[] = new byte[4092];
    while (true) {
      int numOfBytesRead = reader.read(byteArray, 0, 4092);
      if (numOfBytesRead == -1) {
        break;
      }
      // else
      writer.write(byteArray, 0, numOfBytesRead);
    }
    return;
  }

  /**
   * Helper method which reads all inputstream contents as string
   */
  private String readStreamAsString(InputStream is)
      throws FileNotFoundException, IOException {
    ByteArrayOutputStream baos = null;
    try {
      baos = new ByteArrayOutputStream();
      copy(is, baos);
      return baos.toString();
    } finally {
      if (baos != null)
        closeStreamSilently(baos);
    }
  }

  /**
   * Helper method that closes OutputStreams
   */
  private void closeStreamSilently(OutputStream os) {
    if (os == null)
      return;
    // os is not null
    try {
      os.close();
    } catch (IOException x) {
      throw new RuntimeException(
          "This shouldn't happen. exception closing a file", x);
    }
  }

  /**
   * Helper method that closes InputStreams
   */
  private void closeStreamSilently(InputStream os) {
    if (os == null)
      return;
    // os is not null
    try {
      os.close();
    } catch (IOException x) {
      throw new RuntimeException(
          "This shouldn't happen. exception closing a file", x);
    }
  }
  
  /**
   * Gets a file of the local soundwave image of a particular track
   * 
   * @param trackId
   *     The id of the track
   * @return
   *     A File object with proper name
   */
  public File generateSoundwaveFileUri(long trackId) {
    File soundwaveDir = mApplicationContext.getDir(SOUNDWAVE_FILES_DIR, Context.MODE_PRIVATE);
    File trackSoundwave = new File(soundwaveDir, SOUNDWAVE_FILE_PREFIX + trackId + SOUNDWAVE_FILE_SUFFIX);
    return trackSoundwave;
  }
}

Java Source Code List

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