Я пытаюсь заполнить наложение карты маркерами, используя lat и long из существующей базы данных SQLite. Я нашел примеры, где вы вводите lat и long как часть метода, но ни одного, где он заполняется из самой базы данных. Я полагаю, вы используете курсор для этого, но я не уверен, как это сделать. Я использовал курсоры для заполнения ListViews, но не могу изменить код для наложения карты.
Кто-нибудь может указать мне правильное направление или направить меня к полному учебнику?
Вот мой код, так как я новичок в этом, мне нужны примеры, так как пока не могу хорошо построить код.
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;
}
}