Android Open Source - ElevationLogger Trace D B

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License

The source code is released under:

GNU General Public License

Java Source Code

package de.smashnet.elevationlogger;
//from  w ww .j a  va 2  s.c o m
import java.io.EOFException;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.LinkedList;

import android.content.Context;
import android.content.Intent;
import android.net.Uri;
import android.os.Environment;
import android.util.Log;

/**
 * Simple facility to manage traces. Keeps track of what traces have already
 * been sent, and which are still to be sent.
 * 
 * @author Nicolas Inden
 *
 */
public class TraceDB{
  /**
   * The file where the DB is stored
   */
  private File mTraceDBFile;
  /**
   * The list of known traces
   */
  private LinkedList<LocationTrace> mTraces;
  /**
   * The trace that is currently used.
   */
  private LocationTrace mCurrentTrace;
  /**
   * The context this class was instantiated in
   */
  private Context mContext;
  
  /**
   * Open database from given filename. If file does not exist a
   * new DB is created.
   * 
   * @param dbFilename
   */
  public TraceDB(Context con, String dbFilename) {
    mContext = con;
    mTraceDBFile = new File(getStorageDir("ElevationLog","db"), dbFilename);
    if(!mTraceDBFile.exists()) {
      //File does not exist, so create a new empty DB
      try {
        mTraceDBFile.createNewFile();
        mTraces = new LinkedList<LocationTrace>();
        Log.i("DBStorage", "Created new trace DB");
      } catch (IOException e) {
        e.printStackTrace();
        Log.e("DBStorage", "Error creating db file: " + e);
      }
    } else {
      //If file exists, read db
      Log.i("DBStorage", "Loading existing trace DB");
      mTraces = loadTraceDBFile();
    }
  }
  
  /**
   * Starts a new trace for the following locations. This trace is also
   * added to mTraces.
   */
  public void startNewCurrentTrace() {
    mCurrentTrace = new LocationTrace(getStorageDir("ElevationLog","traces"));
    mTraces.add(mCurrentTrace);
  }
  
  /**
   * Add a LocationNode to the current trace.
   * 
   * @param node the node to be added
   */
  public void addNodeToCurrentTrace(LocationNode node) {
    if(mCurrentTrace == null)
      mCurrentTrace = new LocationTrace(getStorageDir("ElevationLog","traces"));
    mCurrentTrace.addNode(node);
  }
  
  /**
   * Closes the current trace.
   */
  public void closeCurrentTrace() {
    mCurrentTrace = null;
  }

  /**
   * Deserializes the db file from storage.
   * 
   * @return res the LinkedList of LocationTraces
   */
  @SuppressWarnings("unchecked")
  private LinkedList<LocationTrace> loadTraceDBFile(){
    try {
      LinkedList<LocationTrace> res = null;
      
      FileInputStream fileIn = new FileInputStream(mTraceDBFile);
      ObjectInputStream in = new ObjectInputStream(fileIn);
      
      res = (LinkedList<LocationTrace>) in.readObject();
      
      in.close();
      fileIn.close();
      Log.i("DBStorage", "Successfully loaded trace DB");
      return res;
    } catch (EOFException ef) {
      Log.w("DBStorage", "Existing db corrupted, creating new one.");
      try {
        mTraceDBFile.createNewFile();
      } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
      }
      return new LinkedList<LocationTrace>();
    } catch (IOException ioe) {
      ioe.printStackTrace();
      Log.e("DBStorage", "Error reading DB: " + ioe);
    } catch (ClassNotFoundException nfe) {
      nfe.printStackTrace();
      Log.e("DBStorage", "No such class: " + nfe);
    }
    return null;
  }
  
  /**
   * Serialize list of traces and save to file.
   * 
   * @throws IOException
   */
  public void writeTraceDBFile(){
    try {
      FileOutputStream fileOut = new FileOutputStream(mTraceDBFile);
      ObjectOutputStream out = new ObjectOutputStream(fileOut);
      
      out.writeObject(mTraces);
      
      out.close();
      fileOut.close();
      
      mContext.sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, Uri.fromFile(mTraceDBFile)));
      Log.i("DBStorage", "Serialized data is saved in " + mTraceDBFile.getAbsolutePath());
    } catch (IOException ioe) {
      ioe.printStackTrace();
      Log.e("DBStorage", "Error writing trace DB file: " + ioe);
    }
  }
  
  public LinkedList<LocationTrace> getTraces() {
    return mTraces;
  }

  /**
   * Returns a File object for ExternalStoragePublicDirectory/$progname/$dirname
   * If the directories do not exists yet, they are created
   * 
   * @param progname the name of this app
   * @param dirname the name of the subdirectory where data should be stored
   * @return the File object representing the storage directory
   */
  public static File getStorageDir(String progname, String dirname) {
        // Get the directory for the user's public pictures directory. 
        File file = new File(Environment.getExternalStoragePublicDirectory(progname), dirname);
        if (!file.exists()) {
          if(!file.mkdirs())
            Log.w("DBStorage", "Directory not created");
        } else {
          Log.i("DBStorage", "Directory exists!");
        }
        return file;
    }
}

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