Android Open Source - classy_apps Classy Fy Provider

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License

The source code is released under:

GNU General Public License

Java Source Code

/**
    Copyright (C) 2014  www.cybersearch2.com.au
// w ww  .  j  av a2 s  . com
    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 au.com.cybersearch2.classyfy.provider;

import javax.inject.Inject;
import javax.inject.Named;

import android.content.ContentProvider;
import android.content.ContentValues;
import android.database.Cursor;
import android.net.Uri;
import au.com.cybersearch2.classyfy.ClassyFyApplication;
import au.com.cybersearch2.classyinject.DI;
import au.com.cybersearch2.classyjpa.AndroidPersistenceEnvironment;


/**
 * ClassyFyProvider
 * Implements android.content.ContentProvider and binds to persistence implementation through Dagger Dependency Injection.
 * This class is only a shell delegating the Provider implementation to ClassyFySearchEngine which implements SearchEngineBase. 
 * Note that Android calls onCreate() before the ClassyFyApplication onCreate() is called where Dependency Injection is
 * initialized. Therefore, any attempt access to an injected variable when onCreate() in this class is called fails with a
 * NullPointerException. Therefore, a dynamic approach has to be used where the dependency binding is delayed until the first 
 * call to this Content Provider is made. This call is orchestrated by  ClassyFyStartup class which upon completion of database
 * initilazation, calls ContentResolver getType() to get the ball rolling.  
 * 
 * @author Andrew Bowley
 * 12/07/2014
 * @see au.com.cybersearch2.classyfy.provider.ClassyFySearchEngine
 * @see au.com.cybersearch2.classyfts.SearchEngineBase
 * @see au.com.cybersearch2.classyfy.ClassyFyStartup
 */
public class ClassyFyProvider extends ContentProvider
{
  /** The actual ContentProvider implementation */
    protected ClassyFySearchEngine classyFySearchEngine;
    /** Flag to control ContentProvider initialization */
    protected volatile boolean searchEngineAvailable;
    /** Android Persistence implementation which has a custom feature of providing the underlying SQLiteOpenHelper */
    @Inject @Named(ClassyFyApplication.PU_NAME) AndroidPersistenceEnvironment androidPersistenceEnvironment;

    /**
     * Create a ClassyFyProvider object
     */
    public ClassyFyProvider()
    {

    }
    
  /**
   * onCreate() called before Application onCreate(), so can do nothing as DI not initialized.
   * @see android.content.ContentProvider#onCreate()
   */
  @Override
  public boolean onCreate()
  {
        return true;
  }

  /**
   * Nothing to do on shutdown. The Application object is responsible for Persistence implementation.
   * @see android.content.ContentProvider#shutdown()
   */
  @Override
    public void shutdown() 
  {
  }

   /**
    * This is called when a client calls {@link android.content.ContentResolver#getType(Uri)}.
    * Returns the "custom" or "vendor-specific" MIME data type of the URI given as a parameter.
    * MIME types have the format "type/subtype". The type value is always "vnd.android.cursor.dir"
    * for multiple rows, or "vnd.android.cursor.item" for a single row. 
    *
    * @param uri The URI whose MIME type is desired.
    * @return The MIME type of the URI.
    * @throws IllegalArgumentException if the incoming URI pattern is invalid.
    */
    @Override
    public String getType(Uri uri)
    {   // ClassyFyStartup class upon completion of database initilazation will call this to start the Provider
        if (!searchEngineAvailable)
            startSearchEngine();
        return classyFySearchEngine.getType(uri);
    }

  /**
   * Perform query with given SQL search parameters
   * @see android.content.ContentProvider#query(android.net.Uri, java.lang.String[], java.lang.String, java.lang.String[], java.lang.String)
   */
  @Override
  public Cursor query(Uri uri, String[] projection, String selection,
          String[] selectionArgs, String sortOrder)
  {
        if (!searchEngineAvailable)
            startSearchEngine();
      return classyFySearchEngine.query(uri, projection, selection, selectionArgs, sortOrder);
  }

    /**
     * Insert content
   * @see android.content.ContentProvider#insert(android.net.Uri, android.content.ContentValues)
   */
  @Override
  public Uri insert(Uri uri, ContentValues values)
  {
        if (!searchEngineAvailable)
            startSearchEngine();
      return classyFySearchEngine.insert(uri, values);
  }

  /**
   * Delete content
   * @see android.content.ContentProvider#delete(android.net.Uri, java.lang.String, java.lang.String[])
   */
  @Override
  public int delete(Uri uri, String selection, String[] selectionArgs)
  {
        if (!searchEngineAvailable)
            startSearchEngine();
      return classyFySearchEngine.delete(uri, selection, selectionArgs);
  }

  /**
   * Update content
   * @see android.content.ContentProvider#update(android.net.Uri, android.content.ContentValues, java.lang.String, java.lang.String[])
   */
  @Override
  public int update(Uri uri, ContentValues values, String selection,
          String[] selectionArgs)
  {
        if (!searchEngineAvailable)
            startSearchEngine();
      return classyFySearchEngine.update(uri, values, selection, selectionArgs);
  }

  /**
   * Start ContentProvider implemetation. This is delayed until first ContentProvider call
   * because this class's onCreate() is called before Application onCreate(), when DI is not initialized.
   */
  protected synchronized void startSearchEngine()
  {
      if (!searchEngineAvailable)
      {
          DI.inject(this);
          classyFySearchEngine = new ClassyFySearchEngine(); 
          // Get the Android SQLiteOpenHelper for "classyfy" persistence unit
          classyFySearchEngine.onCreate(androidPersistenceEnvironment.getSQLiteOpenHelper());
          searchEngineAvailable = true;
      }
  }
}

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