Android Open Source - tum-campus Cafeteria Manager

• Back to App/campus  ↑

From Project

Back to project page tum-campus.

License

The source code is released under:

GNU General Public License

Java Source Code

?package de.tum.in.tumcampus.models;
//ww  w  .j  a  v  a  2  s.  c o m
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import de.tum.in.tumcampus.common.Utils;

import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;

/**
 * Cafeteria Manager, handles database stuff, external imports
 */
public class CafeteriaManager {

  /**
   * Database connection
   */
  private SQLiteDatabase db;

  /**
   * Constructor, open/create database, create table if necessary
   * 
   * <pre>
   * @param context Context
   * </pre>
   */
  public CafeteriaManager(Context context) {
    db = DatabaseManager.getDb(context);

    // create table if needed
    db.execSQL("CREATE TABLE IF NOT EXISTS cafeterias (id INTEGER PRIMARY KEY, name VARCHAR, address VARCHAR)");
  }

  /**
   * Download cafeterias from external interface (JSON)
   * 
   * <pre>
   * @param force True to force download over normal sync period, else false
   * @throws Exception
   * </pre>
   */
  public void downloadFromExternal(boolean force) throws Exception {

    // sync only once per week
    if (!force && !SyncManager.needSync(db, this, 604800)) {
      return;
    }

    String url = "http://lu32kap.typo3.lrz.de/mensaapp/exportDB.php";

    JSONArray jsonArray = Utils.downloadJson(url).getJSONArray("mensa_mensen");
    removeCache();

    // write cafeterias into database, transaction = speedup
    db.beginTransaction();
    try {
      for (int i = 0; i < jsonArray.length(); i++) {
        replaceIntoDb(getFromJson(jsonArray.getJSONObject(i)));
      }
      SyncManager.replaceIntoDb(db, this);
      db.setTransactionSuccessful();
    } finally {
      db.endTransaction();
    }
  }

  /**
   * Returns all cafeterias, filterable by substring of name/address
   * 
   * <pre>
   * @param filter Filter name/address by substring ("" = no filter)
   * @return Database cursor (name, address, _id)
   * </pre>
   */
  public Cursor getAllFromDb(String filter) {
    return db.rawQuery("SELECT name, address, id as _id FROM cafeterias WHERE name LIKE ? OR address LIKE ? "
        + "ORDER BY address like '%Garching%' DESC, name", new String[] { filter, filter });
  }

  /**
   * Get Cafeteria object by JSON object
   * 
   * Example JSON: e.g. {"id":"411","name":"Mensa Leopoldstra\u00dfe","anschrift" :"Leopoldstra\u00dfe 13a, M\u00fcnchen"}
   * 
   * <pre>
   * @param json See example
   * @return Cafeteria object
   * @throws JSONException
   * </pre>
   */
  public static Cafeteria getFromJson(JSONObject json) throws JSONException {

    return new Cafeteria(json.getInt("id"), json.getString("name"), json.getString("anschrift"));
  }

  /**
   * Replace or Insert a cafeteria in the database
   * 
   * <pre>
   * @param c Cafeteria object
   * @throws Exception
   * </pre>
   */
  public void replaceIntoDb(Cafeteria c) throws Exception {
    Utils.log(c.toString());

    if (c.id <= 0) {
      throw new Exception("Invalid id.");
    }
    if (c.name.length() == 0) {
      throw new Exception("Invalid name.");
    }

    db.execSQL("REPLACE INTO cafeterias (id, name, address) VALUES (?, ?, ?)", new String[] { String.valueOf(c.id),
        c.name, c.address });
  }

  /**
   * Removes all cache items
   */
  public void removeCache() {
    db.execSQL("DELETE FROM cafeterias");
  }
}

Java Source Code List

• Back to App/campus  ↑