既存のSQLiteデータベースからのGeoPoints

Question

既存のSQLiteデータベースのlatとlongを使用して、マーカーオーバーレイにマーカーを挿入しようとしています。私は、メソッドの一部としてlatとlongを入力する例を見つけましたが、データベース自体から値が入力される場所はありません。私はあなたがこれを行うためにカーソルを使用すると仮定しますが、私はそれを行う方法がわかりません。 Cursorsを使用してListViewにデータを設定しましたが、マップオーバーレイのコードを変更できないようです。

誰かが正しい方向に向いているのか、私に完全なチュートリアルを教えてもらえますか？

ここまでは私のコードですが、これを初めて覚えているので、コードをうまく構築できない例が必要です。

LocationMap2.java

import com.google.android.maps.MapView; 

import android.app.Activity; 
import android.content.Context; 
import android.database.Cursor; 
import android.os.Bundle; 
import android.util.Log; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.CursorAdapter; 
import android.widget.TextView; 

public class LocationMap2 extends Activity { 

// we use a string to hold the name of our extra, 
// it must include the full package name 
public final static String ID_EXTRA = "com.willows.UKBikeTrails._ID"; 

private AllScotlandHelper dbDataBaseHelper = null; 
private Cursor ourCursor = null; 

public void onCreate(Bundle savedInstanceState) { 
    try { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.map); 

     // this is our MapView element, obtained by id from our XML Layout 
     MapView mapView = (MapView) findViewById(R.id.mapview); 

     // create our database Helper 
     dbDataBaseHelper = new AllScotlandHelper(this); 
     // we call the create right after initializing the helper, just in 
     // case 
     // they have never run the app before 
     dbDataBaseHelper.createDatabase(); 
     // 
     // open the database!! Our helper now has a SQLiteDatabase database 
     // object 
     dbDataBaseHelper.openDataBase(); 
     // get our cursor. A cursor is a pointer to a dataset, in this case 
     // a set of results from a database query 
     ourCursor = dbDataBaseHelper.getCursor(); 
     // tell android to start managing the cursor 
     // we do this just incase our activity is interrupted or ends, we 
     // want the activity 
     // to close and deactivate the cursor, as needed 
     startManagingCursor(ourCursor); 


    } catch (Exception e) { 

     // this is the line of code that sends a real message to the Log 
     Log.e("ERROR", "ERROR IN CODE: " + e.toString()); 

     // this is the line that prints out the location 
     // the code where the error occurred. 
     e.printStackTrace(); 
    } 

} 



class DataBaseAdapter extends CursorAdapter { 
    DataBaseAdapter(Cursor c) { 
     super(LocationMap2.this, c); 
    } 

    public void bindView(View row, Context ctxt, Cursor c) { 
     DataBaseHolder holder = (DataBaseHolder) row.getTag(); 
     holder.populateFrom(c, dbDataBaseHelper); 
    } 

    @Override 
    public View newView(Context ctxt, Cursor c, ViewGroup parent) { 
     LayoutInflater inflater = getLayoutInflater(); 
     View row = inflater.inflate(R.layout.trail_list, parent, false); 
     DataBaseHolder holder = new DataBaseHolder(row); 
     row.setTag(holder); 
     return (row); 
    } 
} 

static class DataBaseHolder { 
    private TextView name = null; 

    DataBaseHolder(View row) { 
     name = (TextView) row.findViewById(R.id.row); 

    } 

    void populateFrom(Cursor c, AllScotlandHelper r) { 
     name.setText(r.getName(c)); 
    } 

} 

} 

LocationMapHelper：

import java.io.FileOutputStream; 
import java.io.IOException; 
import java.io.InputStream; 
import java.io.OutputStream; 
import java.util.Locale; 

import android.content.Context; 
import android.database.Cursor; 
import android.database.SQLException; 
import android.database.sqlite.SQLiteDatabase; 
import android.database.sqlite.SQLiteException; 
import android.database.sqlite.SQLiteOpenHelper; 
import android.database.sqlite.SQLiteQueryBuilder; 
import android.util.Log; 

class LocationMapHelper extends SQLiteOpenHelper { 

//we declare a bunch of useful constants 
//they should be pretty obvious what they are! 
private static final String DATABASE_PATH = "/data/data/com.willows.UKBikeTrails/databases/"; 
private static final String DATABASE_NAME = "ukBikeTrails.db"; 
private static final int SCHEMA_VERSION = 1; 
public static final String TABLE_NAME = "trail_type"; 
public static final String COLUMN_ID = "_id"; 
public static final String COLUMN_TITLE = "TYPE"; 

// BE AWARE - if you make changes to your database using sqlitebrower, you will need to refresh the assets folder in eclipse 
public static final String SECOND_TABLE_NAME = "trail"; 
public static final String SECOND_COLUMN_ID = "_id"; 
public static final String SECOND_COLUMN_TITLE = "NAME"; 

public SQLiteDatabase dbSqlite; 

private final Context myContext; 

public LocationMapHelper (Context context) { 
    super(context, DATABASE_NAME, null, SCHEMA_VERSION); 
    this.myContext = context; 
    // check if exists and copy database from resource 
    //createDB(); 
} 

@Override 
public void onCreate(SQLiteDatabase db) { 
    // check if exists and copy database from resource 

} 

@Override 
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 

} 
public void createDatabase() { 
    createDB(); 
} 

private void createDB() { 

    boolean dbExist = DBExists(); 

    if (!dbExist) { 

     //By calling the method we create an empty database into the default system location 
     //We need this so we can overwrite that database with our database 
     this.getReadableDatabase(); 

     //now we copy the database we included! 
     copyDBFromResource(); 

    } 
} 

private boolean DBExists() { 

    SQLiteDatabase db = null; 

    try { 
     String databasePath = DATABASE_PATH + DATABASE_NAME; 
     db = SQLiteDatabase.openDatabase(databasePath, null, 
       SQLiteDatabase.OPEN_READWRITE); 
     db.setLocale(Locale.getDefault()); 
     db.setLockingEnabled(true); 
     db.setVersion(1); 

    } catch (SQLiteException e) { 

     Log.e("SqlHelper", "database not found"); 

    } 

    if (db != null) { 

     db.close(); 

    } 

    return db != null ? true : false; 

} 

private void copyDBFromResource() { 

    InputStream inputStream = null; 
    OutputStream outStream = null; 
    String dbFilePath = DATABASE_PATH + DATABASE_NAME; 

    try { 

     inputStream = myContext.getAssets().open(DATABASE_NAME); 

     outStream = new FileOutputStream(dbFilePath); 

     byte[] buffer = new byte[1024]; 
     int length; 
     while ((length = inputStream.read(buffer)) > 0) { 
      outStream.write(buffer, 0, length); 
     } 

     outStream.flush(); 
     outStream.close(); 
     inputStream.close(); 

    } catch (IOException e) { 

     throw new Error ("Problem copying database from resource file."); 
    } 
} 

public void openDataBase() throws SQLException { 

    String myPath = DATABASE_PATH + DATABASE_NAME; 
    dbSqlite = SQLiteDatabase.openDatabase(myPath, null, 
      SQLiteDatabase.OPEN_READWRITE); 
} 

@Override 
public synchronized void close() { 

    if (dbSqlite !=null) 
    { 
     dbSqlite.close(); 
    } 
    super.close(); 
} 

//the following two methods return the column you want and it's title (getName) 
public Cursor getCursor() { 

    SQLiteQueryBuilder queryBuilder = new SQLiteQueryBuilder(); 

    queryBuilder.setTables(TABLE_NAME); 

    String[] asColumnsToReturn = new String[] { COLUMN_ID, COLUMN_TITLE }; 

    //make sure you get your search pass correctly! 
    Cursor mCursor = queryBuilder.query(dbSqlite, asColumnsToReturn, null, 
      null, null, null, "_id"); 
    //the name after the nulls dictates how the results are returned. ie in order of "column name" 

    return mCursor; 
} 


public String getName(Cursor c) { 
    return(c.getString(1)); 
    //where 1 refers to COLUMN_TITLE line 11 rows above (0 would be COLUMN_ID and so on) 
} 

public Cursor getLatLong(String id) {  
    String[] args = null; 
    String query = "SELECT _id, LATITUDE,LONGITUDE FROM trail"; 

    return (getReadableDatabase().rawQuery(query, args)); 
} 

MapItemizedOverlay：

import java.util.ArrayList; 
import android.app.AlertDialog; 
import android.content.Context; 
import android.graphics.drawable.Drawable; 
import com.google.android.maps.ItemizedOverlay; 
import com.google.android.maps.OverlayItem; 

public class MapItemizedOverlay extends ItemizedOverlay<OverlayItem> { 
private ArrayList<OverlayItem> mOverlays = new ArrayList<OverlayItem>(); 
private Context mContext; 

public MapItemizedOverlay(Drawable defaultMarker, Context context) { 
    super(boundCenterBottom(defaultMarker)); 
    mContext = context; 
} 

public void addOverlay(OverlayItem overlay) { 
    mOverlays.add(overlay); 
    populate(); 
} 

@Override 
protected OverlayItem createItem(int i) { 
    return mOverlays.get(i); 
} 

@Override 
public int size() { 
    return mOverlays.size(); 
} 

@Override 
protected boolean onTap(int index) { 
    OverlayItem item = mOverlays.get(index); 
    AlertDialog.Builder dialog = new AlertDialog.Builder(mContext); 
    dialog.setTitle(item.getTitle()); 
    dialog.setMessage(item.getSnippet()); 
    dialog.show(); 
    return true; 
} 
} 

Answer 1

あなたはどんな長い/ int型の値のようなデータベースからあなたgeopointsを読み、[GeoPointをインスタンス化数字からオブジェクトを抽出してに追加します。

Cursor c = getContentResolver().query(... some uri ..., new String[]{"lat", "lon"}, null, null, null); 
while (c.moveToNext()) { 
    GeoPoint gp = new GeoPoint(c.getInt(c.getColumnIndex("lat")), c.getInt(c.getColumnIndex("lon"))); 
    .. add to map overlay ... 
}