Bookmark.java :  » Pdf » apv » cx » hell » android » pdfview » Android Open Source

/*
 * Copyright 2010 Ludovic Drolez
 * 
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 * 
 */

package cx.hell.android.pdfview;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

/**
 * Class to manage the last opened page and bookmarks of PDF files
 * 
 * @author Ludovic Drolez
 * 
 */
public class Bookmark {

  /** db fields */
  public static final String KEY_ID = "_id";
  public static final String KEY_BOOK = "book";
  public static final String KEY_NAME = "name";
  public static final String KEY_PAGE = "page";
  public static final String KEY_COMMENT = "comment";
  public static final String KEY_TIME = "time";

  private static final int DB_VERSION = 2;

  private static final String DATABASE_CREATE = "create table bookmark "
      + "(_id integer primary key autoincrement, "
      + "book text not null, name text not null, "
      + "page integer, comment text, time integer);";

  private final Context context;

  private DatabaseHelper DBHelper;
  private SQLiteDatabase db;

  /**
   * Constructor
   * 
   * @param ctx
   *            application context
   */
  public Bookmark(Context ctx) {
    this.context = ctx;
    DBHelper = new DatabaseHelper(context);
  }

  /**
   * Database helper class
   */
  private static class DatabaseHelper extends SQLiteOpenHelper {
    DatabaseHelper(Context context) {
      super(context, "bookmark.db", null, DB_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
      db.execSQL(DATABASE_CREATE);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
      if (oldVersion == 1) {
        db.execSQL("ALTER TABLE bookmark ADD COLUMN time integer");
      }
    }
  }

  /**
   * open the bookmark database
   * 
   * @return the Bookmark object
   * @throws SQLException
   */
  public Bookmark open() throws SQLException {
    db = DBHelper.getWritableDatabase();
    return this;
  }

  /**
   * close the database
   */
  public void close() {
    DBHelper.close();
  }

  /**
   * Set the last page seen for a file
   * 
   * @param file
   *            full file path
   * @param page
   *            last page
   */
  public void setLast(String file, int page) {
    String md5 = nameToMD5(file);
    ContentValues cv = new ContentValues();
    cv.put(KEY_BOOK, md5);
    cv.put(KEY_PAGE, page);
    cv.put(KEY_NAME, "last");
    cv.put(KEY_TIME, System.currentTimeMillis() / 1000);
    if (db.update("bookmark", cv, KEY_BOOK + "='" + md5 + "' AND "
        + KEY_NAME + "= 'last'", null) == 0) {
      db.insert("bookmark", null, cv);
    }
  }

  /**
   * Get the last recorded page for the given file
   * 
   * @param file
   * @return page number (0-based) or 0 if not found
   */
  public int getLast(String file) {
    int page = 0;
    String md5 = nameToMD5(file);

    Cursor cur = db.query(true, "bookmark", new String[] { KEY_PAGE },
        KEY_BOOK + "='" + md5 + "' AND " + KEY_NAME + "= 'last'", null,
        null, null, null, "1");
    if (cur != null) {
      if (cur.moveToFirst()) {
        page = cur.getInt(0);
      }
    }
    cur.close();
    return page;
  }

  /**
   * Hash the file name to be sure that no strange characters will be in the
   * DB Can also later add the file size to the hash.
   * 
   * @param file
   *            path
   * @return md5
   */
  private String nameToMD5(String file) {
    // Create MD5 Hash
    MessageDigest digest;
    try {
      digest = java.security.MessageDigest.getInstance("MD5");
    } catch (NoSuchAlgorithmException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
      return "";
    }

    digest.update(file.getBytes());
    byte messageDigest[] = digest.digest();
    StringBuffer hexString = new StringBuffer();
    for (int i = 0; i < messageDigest.length; i++)
      hexString.append(Integer.toHexString(0xFF & messageDigest[i]));
    return hexString.toString();
  }
}