我使用此方法在SQLite中保存标记：
public long addMarker(Markers marker) {
SQLiteDatabase db=null;
ContentValues values = new ContentValues();
values.put(COLUMN_ADDRESS, marker.get_address());
values.put(COLUMN_COUNTRY, marker.get_country());
values.put(COLUMN_LAT, marker.get_lat());
values.put(COLUMN_LNG, marker.get_lng());
values.put(COLUMN_IMAGE, marker.get_image());
db = getWritableDatabase();
long result = db.insert(TABLE_LOCATIONS, null, values);
if (result>0){
db.close();
}
return result;
}
然后onMarkerClick我必须获取我使用LatLng点击的标记的所有信息作为参数。
这是我使用的方法：
public Markers getOneMarker(double lat, double lng) {
SQLiteDatabase db = this.getReadableDatabase();
Cursor curs = db.query(true,TABLE_LOCATIONS,new String[]{COLUMN_ID,
COLUMN_ADDRESS,COLUMN_COUNTRY,
COLUMN_LAT,COLUMN_LNG,COLUMN_IMAGE},
COLUMN_LAT+"="+lat+" AND "+COLUMN_LNG+"="+lng,
null,null,null,null,null);
Markers marker = null;
if (curs != null) {
curs.moveToFirst();
try{
marker = new Markers(Integer.valueOf(curs.getString(0)),curs.getString(1), curs.getString(2),Double.valueOf(curs.getString(3)),Double.valueOf(curs.getString(4)),curs.getString(5));
}catch (CursorIndexOutOfBoundsException e){
e.printStackTrace();
marker = new Markers("Address for location unavailable ", "N/A", lat, lng, "image");
}
}
assert curs != null;
curs.close();
db.close();
return marker;
}
90％的时间我得到了我想要的（地址和国家名称），但另外10％我得到了"Address for location unavailable ", "N/A"。我在Toast中设置onClick()来检查地理编码器但是没问题。我收到的是地址，但不是来自数据库。有任何想法吗？
编辑：是否可能是同步问题？如果它是如此打开标记后它保存在数据库中。
在onPostExecute()中的异步任务类中调用保存在DB中
这是我的DatabaseHandler课程：
public class DatabaseHandler extends SQLiteOpenHelper {
private static DatabaseHandler sInstance;
private static final int DATABASE_VERSION = 1;
private static final String DATABASE_NAME = "locations.db";
public static final String TABLE_LOCATIONS = "locations";
public static final String COLUMN_ID = "_id";
public static final String COLUMN_ADDRESS = "_address";
public static final String COLUMN_COUNTRY = "_country";
public static final String COLUMN_LAT = "_lat";
public static final String COLUMN_LNG = "_lng";
public static final String COLUMN_IMAGE = "_image";
private DatabaseHandler(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
public static synchronized DatabaseHandler getInstance(Context context) {
if (sInstance == null) {
sInstance = new DatabaseHandler(context.getApplicationContext());
}
return sInstance;
}
@Override
public void onCreate(SQLiteDatabase db) {
String query = "CREATE TABLE " +
TABLE_LOCATIONS + "(" +
COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
COLUMN_ADDRESS + " TEXT, " +
COLUMN_COUNTRY + " TEXT, " +
COLUMN_LAT + " REAL, " +
COLUMN_LNG + " REAL, " +
COLUMN_IMAGE + " TEXT " +
");";
db.execSQL(query);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + TABLE_LOCATIONS);
onCreate(db);
}
public long addMarker(Markers marker) {
SQLiteDatabase db = null;
ContentValues values = new ContentValues();
values.put(COLUMN_ADDRESS, marker.get_address());
values.put(COLUMN_COUNTRY, marker.get_country());
values.put(COLUMN_LAT, marker.get_lat());
values.put(COLUMN_LNG, marker.get_lng());
values.put(COLUMN_IMAGE, marker.get_image());
db = getWritableDatabase();
long result = db.insert(TABLE_LOCATIONS, null, values);
if (result>0){
db.close();
}
return result;
}
public void deleteMarker(int id) {
SQLiteDatabase db = getWritableDatabase();
db.execSQL("DELETE FROM " + TABLE_LOCATIONS + " WHERE " + COLUMN_ID + "=\"" + id + "\";");
}
public Markers getOneMarker(double lat, double lng) {
SQLiteDatabase db = getReadableDatabase();
Cursor curs = db.query(true,TABLE_LOCATIONS,new String[]{COLUMN_ID,
COLUMN_ADDRESS,COLUMN_COUNTRY,
COLUMN_LAT,COLUMN_LNG,COLUMN_IMAGE},
COLUMN_LAT+"="+lat+" AND "+COLUMN_LNG+"="+lng,
null,null,null,null,null);
Markers marker = null;
if( curs != null && curs.moveToFirst() && curs.getCount() >= 1 ){
do{
try{
marker = new Markers(Integer.valueOf(curs.getString(0)),curs.getString(1), curs.getString(2),Double.valueOf(curs.getString(3)),Double.valueOf(curs.getString(4)),curs.getString(5));
}catch(CursorIndexOutOfBoundsException e){
e.printStackTrace();
marker = new Markers("Address for location unavailable ", "N/A", lat, lng, "image");
}
} while(curs.moveToNext());
}
if (curs != null) {
curs.close();
}
db.close();
public void updateMarker(int id,String link){
SQLiteDatabase db = this.getWritableDatabase();
String query = "UPDATE "+TABLE_LOCATIONS + " SET "+ COLUMN_IMAGE + "="+link+" WHERE " + COLUMN_ID + "=\"" + id + "\";";
db.execSQL(query);
}
public int getID(double lat, double lng){
Markers marker = getOneMarker(lat,lng);
return marker.get_id();
}
}
这是我称之为Activity的方法：
@Override
public boolean onMarkerClick(Marker marker) {
try {
Intent intent = new Intent(getApplicationContext(), MarkerActivity.class);
DatabaseHandler databaseHandler = DatabaseHandler.getInstance(getApplicationContext());
Markers tempMarker = databaseHandler.getOneMarker(marker.getPosition().latitude, marker.getPosition().longitude);
addressLine = tempMarker.get_address();
country = tempMarker.get_country();
String lat = String.valueOf(tempMarker.get_lat());
String lng = String.valueOf(tempMarker.get_lng());
intent.putExtra("address", addressLine);
intent.putExtra("country", country);
intent.putExtra("lat", lat);
intent.putExtra("lng", lng);
startActivity(intent);
} catch (NullPointerException e) {
e.printStackTrace();
}
return true;
}
我用以下方法保存它们：
@Override
protected void onPostExecute(Markers markers) {
DatabaseHandler databaseHandler = DatabaseHandler.getInstance(getApplicationContext());
id = databaseHandler.addMarker(markers);
Toast.makeText(getApplicationContext(), String.valueOf(id), Toast.LENGTH_SHORT).show();
super.onPostExecute(markers);
markerList.add(latLng);
}
答案 0 :(得分：-1)
从光标获取信息的最佳方法是，
if( curs != null && curs.moveToFirst() && curs.getCount() >= 1 ){
do {
....
} while( curs.moveToNext() );
}
如果您正在使用多线程处理（例如项目中的AsyncTask），最佳做法是以SQLite方式使用Singletone数据库访问。这意味着您需要设计DatabaseHelper类，如下所示，
public class DatabaseHelper extends SQLiteOpenHelper {
private static DatabaseHelper sInstance;
private static final String DATABASE_NAME = "database_name";
private static final String DATABASE_TABLE = "table_name";
private static final int DATABASE_VERSION = 1;
...
public static synchronized DatabaseHelper getInstance(Context context) {
if (sInstance == null) {
sInstance = new DatabaseHelper(context.getApplicationContext());
}
return sInstance;
}
/**
* Constructor should be private to prevent direct instantiation.
* make call to static method "getInstance()" instead.
*/
private DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
}
现在，当您需要打开数据库帮助程序时，您需要访问类似的项目
DatabaseHelper db = DatabaseHelper.getInstance(context);