在 SQLite 中存储已解析的 Rss 项

Question

作为我的第一个 Android 项目，我正在尝试制作一个 RSS reader 应用程序，其中的 Listview 项目可以保存到 SQLite，允许它们离线阅读。但是，当尝试使用带有 SimpleCursorAdapter 的查询在列表视图中 return 新闻标题时，列表视图显示文本 "title"，而不是新闻的实际标题。

这似乎表明项目没有存储到数据库中，或者内容值没有被正确分配。

谁能看出我可能哪里出错了？

提前致谢！

RssItem.java

public class RssItem {

protected String _id;
public String title;
protected String link;
protected String page;
protected String completeTextLink;
protected String mainBody;


public String get_id() {
    return _id;
}

public void set_id(String _id) {
    this._id = _id;
}

//Title get/set
public String getTitle() {
    return title;
}

public void setTitle(String title) {
    this.title = title;
}


//Link get/set
public String getLink() {
    return link;
}

public void setLink(String link) {
    this.link = link;
}


//CompleteTextLink get/set
public String getCompleteTextLink() {
    return completeTextLink;
}

public void setCompleteTextLink(String completeTextLink) {
    this.completeTextLink = completeTextLink;
}


//MainBody get/set
public String getMainBody() {
    return mainBody;
}

public void setMainBody(String mainBody) {
    this.mainBody = mainBody;
}


//Page get/set
public String getPage() {
    return page;
}

public void setPage(String page) {
    this.page = page;
}

@Override
public String toString() {
    return title;
}}

MainActivity.java

public class MainActivity extends Activity {

private MainActivity local;
private DatabaseHandler db;

//Method to create main application view
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    //set view
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    setContentView(R.layout.main);


    //**************************create a button to move to the user's saved feeds screen*****************************

    Button myFeedsButton = (Button) findViewById(R.id.myFeedsButton);
    myFeedsButton.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v)
        {
            startActivity(new Intent(MainActivity.this, MyFeedsScreen.class));
        }
    });

    //***************************************************************************************************************

    //Create new instance of database handler
    db = new DatabaseHandler(this);
    //set local ref to this activity
    local = this;

    GetRSSDataTask task = new GetRSSDataTask();

    //start download Rss task - execute method calls the
    task.execute("http://feeds.bbci.co.uk/news/rss.xml?edition=uk");

    //debug thread name
    Log.d("RssReaderApp", Thread.currentThread().getName());
}

//*******************************************************************************************************************

private class GetRSSDataTask extends AsyncTask<String, Void, List<RssItem>>
{
    @Override
    protected List<RssItem> doInBackground(String... urls) {

        //debug task thread name
        Log.d("RssReaderApp", Thread.currentThread().getName());

        try {
            //create a new reader
            RssReader rssReader = new RssReader(urls[0]);

            //Parse RSS, get items
            return rssReader.getItems();
        } catch (Exception e) {
            Log.e("RssReaderApp", e.getMessage());
        }

        return null;

    }//doInBackground


    //is invoked on UI thread after background tasks are complete.
    // Results of background task are passed here as a parameter
    @Override
    protected void onPostExecute(List<RssItem> result)
    {
        //Gets listview from main.xml
        final ListView listItems = (ListView) findViewById(R.id.listMainView);

        //Creates a new list adapter - displays an array of strings in listview
        ArrayAdapter<RssItem> adapter = new ArrayAdapter<RssItem>(local, android.R.layout.simple_list_item_1, result);
        //Set list adapter for listView
        listItems.setAdapter(adapter);

        //OnItemClick listener set to allow user to access content from title
        listItems.setOnItemClickListener(new ListListener(result, local));



        //*******************************LONG CLICK FUNCTIONALITY******************************************
        //Set new long click listener which should allow item to be stored to db
        listItems.setLongClickable(true);
        listItems.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {

            @Override
            public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {

                try {

                    db.open();
                    RssItem item = new RssItem();
                    item.title = "title";
                    item.link = "link";
                    item.completeTextLink ="completeTextLink";
                    item.page = "page";

                    db.insertRssItem(item);

                   db.close();

                } catch (SQLException e)
                    {
                        e.printStackTrace();
                    }


                Toast.makeText(getBaseContext(), "Item saved in My Feeds!", Toast.LENGTH_SHORT).show();
                return true;


            }
        });

        }//onPostExecute
    }}//class

DatabaseHandler.java

public class DatabaseHandler extends SQLiteOpenHelper {

private static final String DATABASE_NAME = "news_db";
public static SQLiteDatabase db;
private static final int DATABASE_VERSION = 32;
protected static final String TABLE_NEWS = "news";
private static final String TAG = "TAG";
private static final String TAG1 = "TAG1";
static String columnTitle = "title";
protected static final String _id = "_id";


//Methods for tables
public DatabaseHandler(Context context) {
    super(context, DATABASE_NAME, null, DATABASE_VERSION);
}

@Override
public void onCreate(SQLiteDatabase db) {

    String CREATE_TABLE_NEWS = "CREATE TABLE " + TABLE_NEWS + "(_id VARCHAR, title TEXT, link TEXT, completeTextLink TEXT, mainBody Text, page TEXT)";
    db.execSQL(CREATE_TABLE_NEWS);
    Log.w(TAG, "Database has been created");
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    db.execSQL("DROP TABLE IF EXISTS " + TABLE_NEWS);
    onCreate(db);
}

public void open() throws SQLException {
    db = this.getWritableDatabase();
}


//Method to insert new rssItem object to the database

public void insertRssItem(RssItem rssItem) {
    SQLiteDatabase db = this.getWritableDatabase();
    ContentValues contentValues = new ContentValues();
    contentValues.put("_id", rssItem._id);
    contentValues.put("title", rssItem.title);
    contentValues.put("link", rssItem.link);
    contentValues.put("mainBody", rssItem.mainBody);
    contentValues.put("completeTextLink", rssItem.completeTextLink);
    contentValues.put("page", rssItem.page);

    db.insert(TABLE_NEWS, "title", contentValues);
    Log.d(TAG1, "ITEM SAVED IN DATABASE!!!");

}//insert item method


//Method to return all news for a given item
public List<RssItem> getAllNewsForItem(String page) {
    List<RssItem> SavedNewsList = new ArrayList<RssItem>();
    Cursor cursor = db.rawQuery("select _id, completeTextLink, title, link, mainBody, page" +
            " FROM " + TABLE_NEWS + " where page = ?", new String[]{page});

    cursor.moveToFirst();
    while (!cursor.isAfterLast()) {
        RssItem rssItem = new RssItem();
        rssItem._id = cursor.getString(0);
        rssItem.completeTextLink = cursor.getString(1);
        rssItem.title = cursor.getString(2);
        rssItem.link = cursor.getString(3);
        rssItem.mainBody = cursor.getString(4);
        rssItem.page = page;

        SavedNewsList.add(rssItem);
        cursor.moveToNext();
    }
    cursor.close();
    return SavedNewsList;
}


//get data from database for listview
public Cursor getData() {
    SQLiteDatabase db = this.getReadableDatabase();
    Cursor cursor = db.rawQuery("SELECT * FROM " + TABLE_NEWS, null);
    return cursor;
}}

MyFeedsScreen.java

public class MyFeedsScreen extends ListActivity {

DatabaseHandler dbHandler;
SimpleCursorAdapter dataAdapter;


@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.my_feeds_screen);
    dbHandler = new DatabaseHandler(MyFeedsScreen.this);
    displayList();
}

public void displayList() {
    dbHandler.getWritableDatabase();
    dbHandler = new DatabaseHandler(this);

    Cursor cursor = dbHandler.getData();
    String from[] = new String[]{dbHandler.columnTitle};
    int to[] = new int[]{R.id.textView1};
    dataAdapter = new SimpleCursorAdapter(this, R.layout.row_item, cursor, from, to, 0);

    ListView lv = getListView();
    lv.setAdapter(dataAdapter);


}}

Answer 1

您应该从长按侦听器中调用 getItemAtPosition(int position)。这将使您从支持 ListView 的集合中获得 Object，在本例中，是来自您的 RssReader 的用户长按的文章。有点像：

...
db.open();
RssArticleThing fromList = (RssArticleThing) listItems.getItemAtPosition(position);
RssItem item = new RssItem();
item.title = fromList.title;
...

http://developer.android.com/reference/android/widget/AdapterView.html#getItemAtPosition(int)

在 SQLite 中存储已解析的 Rss 项

Storing parsed Rss items within SQLite

java

sqlite

rss

android

simplecursoradapter