Get Latitude and Longitude from SQLite database fo

问题:

If I store the Latitude and Longitude of a bunch of locations in a SQLite Database, how would I retrieve these values and place them each in an OverlayItem class for use in Google's Map code?

Database name: database

Table name: place

Fields in place Table:

• id
• title
• description
• latitude
• longitude

How do I get the latitude and longitude data of each location and add it to an ArrayList itemOverlay?

Do you have any ideas or an example? Thanks you so much

回答1:

You would want to do a query like this:

SELECT title, description, latitude, longitude
FROM place

Which can be done in Android like this:

    /* 
       databaseObject = YourDbHelper#getReadableDatabase();
    */
    ArrayList<OverlayItem> items = new ArrayList<OverlayItem>();
    Cursor locationCursor = databaseObject.query("place", new String[]{
            "title", "description", "latitude", "longitude"}, null, null,
            null, null, null);

    locationCursor.moveToFirst();

    do {
        String title = locationCursor.String(locationCursor
                .getColumnIndex("title"));
        String description = locationCursor.String(locationCursor
                .getColumnIndex("description"));
        int latitude = (int) (locationCursor.getDouble(locationCursor
                .getColumnIndex("latitude")) * 1E6);
        int longitude = (int) (locationCursor.getDouble(locationCursor
                .getColumnIndex("longitude")) * 1E6);

        items.add(new OverlayItem(new GeoPoint(latitude, longitude), title,
                description));
    } while (locationCursor.moveToNext());

You need to multiply the values by 1E6 because Android uses an integer representation of the lat/long values. If you already took care of this when populating the database, skip the multiplication and use locationCursor.getInt(...).