Android Open Source - tum-campus Feed Item Manager

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License

The source code is released under:

GNU General Public License

Java Source Code

?package de.tum.in.tumcampus.models;
/*w ww.  ja va2  s.  com*/
import java.net.URLEncoder;
import java.util.Date;

import org.json.JSONArray;
import org.json.JSONObject;

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

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

/**
 * Feed item Manager, handles database stuff, external imports
 */
public class FeedItemManager {

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

  /**
   * Last insert counter
   */
  public static int lastInserted = 0;

  /**
   * Additional information for exception messages
   */
  public String lastInfo = "";

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

    // create table if needed
    db.execSQL("CREATE TABLE IF NOT EXISTS feeds_items ("
        + "id INTEGER PRIMARY KEY AUTOINCREMENT, feedId INTEGER, "
        + "title VARCHAR, link VARCHAR, description VARCHAR, date VARCHAR, image VARCHAR)");
  }

  /**
   * Download feed items from external interface (YQL+JSON)
   * 
   * <pre>
   * @param id Feed-ID
   * @param retry Retry download after resolving RSS-Url
   * @param force True to force download over normal sync period, else false
   * @throws Exception
   * </pre>
   */
  public void downloadFromExternal(int id, boolean retry, boolean force) throws Exception {
    String syncId = "feeditem" + id;
    if (!force && !SyncManager.needSync(db, syncId, 900)) {
      return;
    }

    cleanupDb();
    int count = Utils.dbGetTableCount(db, "feeds_items");

    Cursor feed = db.rawQuery("SELECT feedUrl FROM feeds WHERE id = ?", new String[] { String.valueOf(id) });
    feed.moveToNext();
    String feedUrl = feed.getString(0);
    feed.close();

    lastInfo = feedUrl;
    String baseUrl = "http://query.yahooapis.com/v1/public/yql?format=json&q=";
    String query = URLEncoder.encode("SELECT title, link, description, pubDate, enclosure.url "
        + "FROM rss WHERE url=\"" + feedUrl + "\" LIMIT 25");

    JSONObject jsonObj = Utils.downloadJson(baseUrl + query).getJSONObject("query");

    if (jsonObj.isNull("results") && !retry) {
      String url = Utils.getRssLinkFromUrl(feedUrl);

      if (!url.equals(feedUrl)) {
        db.execSQL("UPDATE feeds SET feedUrl=? WHERE id = ?", new String[] { url, String.valueOf(id) });
        downloadFromExternal(id, true, force);
        return;
      }
    }
    Object obj = jsonObj.getJSONObject("results").get("item");

    JSONArray jsonArray = new JSONArray();
    if (obj instanceof JSONArray) {
      jsonArray = (JSONArray) obj;
    } else {
      jsonArray.put(obj);
    }

    deleteFromDb(id);
    db.beginTransaction();
    try {
      for (int j = 0; j < jsonArray.length(); j++) {
        insertIntoDb(getFromJson(id, jsonArray.getJSONObject(j)));
      }
      SyncManager.replaceIntoDb(db, syncId);
      db.setTransactionSuccessful();
    } finally {
      db.endTransaction();
    }
    // update last insert counter
    lastInserted += Utils.dbGetTableCount(db, "feeds_items") - count;
  }

  /**
   * Get all feed items for a feed from the database
   * 
   * <pre>
   * @param feedId Feed ID
   * @return Database cursor (image, title, description, link, _id)
   * </pre>
   */
  public Cursor getAllFromDb(String feedId) {
    return db.rawQuery("SELECT image, title, description, link, id as _id "
        + "FROM feeds_items WHERE feedId = ? ORDER BY date DESC", new String[] { feedId });
  }

  /**
   * Checks if the feeds_items table is empty
   * 
   * @return true if no feed items are available, else false
   */
  public boolean empty() {
    boolean result = true;
    Cursor c = db.rawQuery("SELECT id FROM feeds_items LIMIT 1", null);
    if (c.moveToNext()) {
      result = false;
    }
    c.close();
    return result;
  }

  /**
   * Convert JSON to FeedItem and download feed item iamge
   * 
   * Example JSON: e.g. { "title": "US-Truppenabzug aus Afghanistan: \"Verlogen und verkorkst\"", "description": "...", "link":
   * "http://www.n-tv.de/politik/pressestimmen/Verlogen-und-verkorkst-article3650731.html" , "pubDate": "Thu, 23 Jun 2011 20:06:53 GMT", "enclosure": { "url":
   * "http://www.n-tv.de/img/30/304801/Img_4_3_220_Pressestimmen.jpg" }
   * 
   * <pre>
   * @param feedId Feed ID
   * @param json see above
   * @return Feeds
   * @throws Exception
   * </pre>
   */
  public static FeedItem getFromJson(int feedId, JSONObject json) throws Exception {

    String target = "";
    if (json.has("enclosure")) {
      final String enclosure = json.getJSONObject("enclosure").getString("url");

      target = Utils.getCacheDir("rss/cache") + Utils.md5(enclosure) + ".jpg";
      Utils.downloadFileThread(enclosure, target);
    }
    Date pubDate = new Date();
    if (json.has("pubDate")) {
      pubDate = Utils.getDateTimeRfc822(json.getString("pubDate"));
    }
    String description = "";
    if (json.has("description") && !json.isNull("description")) {
      // decode HTML entites, remove links, images, etc.
      description = Html.fromHtml(json.getString("description").replaceAll("\\<.*?\\>", "")).toString();
    }
    return new FeedItem(feedId, json.getString("title").replaceAll("\n", ""), json.getString("link"), description,
        pubDate, target);
  }

  /**
   * Insert a feed item in the database
   * 
   * <pre>
   * @param n FeedItem object
   * @throws Exception
   * </pre>
   */
  public void insertIntoDb(FeedItem n) throws Exception {
    if (n.feedId <= 0) {
      throw new Exception("Invalid feedId.");
    }
    if (n.link.length() == 0) {
      throw new Exception("Invalid link.");
    }
    if (n.title.length() == 0) {
      throw new Exception("Invalid title.");
    }
    db.execSQL("INSERT INTO feeds_items (feedId, title, link, description, "
        + "date, image) VALUES (?, ?, ?, ?, ?, ?)", new String[] { String.valueOf(n.feedId), n.title, n.link,
        n.description, Utils.getDateTimeString(n.date), n.image });
  }

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

  /**
   * Deletes feed items from the database
   * 
   * <pre>
   * @param feedId Feed ID
   * </pre>
   */
  public void deleteFromDb(int feedId) {
    db.execSQL("DELETE FROM feeds_items WHERE feedId = ?", new String[] { String.valueOf(feedId) });
  }

  /**
   * Removes all old items (older than 7 days)
   */
  public void cleanupDb() {
    db.execSQL("DELETE FROM feeds_items WHERE date < date('now','-7 day')");
  }
}

Java Source Code List

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