android - 如何从 android 微调器上的数据库中检索数据？

Question

我已经使用了微调器并在 sqlite 中拥有了数据库，现在我想从 android 中微调器的数据库中检索数据或名称。如何实现这个？谁能给我相同的示例代码？

Spinner spinname; 
spinname =(Spinner)findViewById(R.id.name); 

这是我的微调器名称。我想从数据库中检索微调器上的数据。 DBAdapter 类:

public class DBAdapter extends SQLiteOpenHelper {

private static String DB_PATH = "";
private static final String DB_NAME = "SocialReminder.sqlite";

private SQLiteDatabase myDataBase;
private final Context myContext;

private static DBAdapter mDBConnection;
/**
 * Constructor 
 * Takes and keeps a reference of the passed context in order to access to the application assets and resources.
 * @param context
 */
private DBAdapter(Context context) 
{
    super(context, DB_NAME, null, 1);
    this.myContext = context;
    DB_PATH = "/data/data/"+ context.getApplicationContext().getPackageName()+ "/databases/";
    try {
        createDataBase();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    // The Android's default system path of your application database is
    // "/data/data/mypackagename/databases/"
}

/**
 * getting Instance
 * @param context
 * @return DBAdapter
 */

public static synchronized DBAdapter getDBAdapterInstance(Context context)
{
    if (mDBConnection == null) 
    {
        mDBConnection = new DBAdapter(context);
    }
    return mDBConnection;
}

/**
 * Creates an empty database on the system and rewrites it with your own database.
 **/
public void createDataBase() throws IOException 
{
    boolean dbExist = checkDataBase();
    if (dbExist) 
    {
        // do nothing - database already exist
    } else {
        // By calling following method 
        // 1) an empty database will be created into the default system path of your application 
        // 2) than we overwrite that database with our database.
        this.getReadableDatabase();
        try {
            copyDataBase();
        } catch (IOException e) {
            throw new Error("Error copying database");
        }
    }
}

/**
 * Check if the database already exist to avoid re-copying the file each time you open the application.
 * @return true if it exists, false if it doesn't
 */
private boolean checkDataBase() 
{
    SQLiteDatabase checkDB = null;
    try {
        String myPath = DB_PATH + DB_NAME;
        checkDB = SQLiteDatabase.openDatabase(myPath, null,SQLiteDatabase.OPEN_READONLY);

    } catch (SQLiteException e) 
    {
        // database does't exist yet.
    }
    if (checkDB != null) {
        checkDB.close();
    }
    return checkDB != null ? true : false;
}

/**
 * Copies your database from your local assets-folder to the just created
 * empty database in the system folder, from where it can be accessed and
 * handled. This is done by transfering bytestream.
 * */
private void copyDataBase() throws IOException {
        // Open your local db as the input stream
    InputStream myInput = myContext.getAssets().open(DB_NAME);
        // Path to the just created empty db
    String outFileName = DB_PATH + DB_NAME;
        // Open the empty db as the output stream
    OutputStream myOutput = new FileOutputStream(outFileName);
        // transfer bytes from the inputfile to the outputfile
    byte[] buffer = new byte[1024];
    int length;

    while ((length = myInput.read(buffer)) > 0)
    {
        myOutput.write(buffer, 0, length);
    }
        // Close the streams
    myOutput.flush();
    myOutput.close();
    myInput.close();
}

/**
 * Open the database
 * @throws SQLException
 */
public void openDataBase() throws SQLException {
    String myPath = DB_PATH + DB_NAME;
    myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);      
}

/**
 * Close the database if exist
 */
@Override
public synchronized void close() 
{
    if (myDataBase != null)
        myDataBase.close();
    super.close();
}

/**
 * Call on creating data base for example for creating tables at run time
 */
@Override
public void onCreate(SQLiteDatabase db) 
{

}

/**
 * can used for drop tables then call onCreate(db) function to create tables again - upgrade
 */
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
{

}

// ----------------------- CRUD Functions ------------------------------

/**
 * This function used to select the records from DB.
 * @param tableName
 * @param tableColumns
 * @param whereClase
 * @param whereArgs
 * @param groupBy
 * @param having
 * @param orderBy
 * @return A Cursor object, which is positioned before the first entry.
 */
public Cursor selectRecordsFromDB(String tableName, String[] tableColumns,String whereClase, String whereArgs[], String groupBy,String having, String orderBy) 
{
    return myDataBase.query(tableName, tableColumns, whereClase, whereArgs,groupBy, having, orderBy);
}

/**
 * select records from db and return in list
 * @param tableName
 * @param tableColumns
 * @param whereClase
 * @param whereArgs
 * @param groupBy
 * @param having
 * @param orderBy
 * @return ArrayList<ArrayList<String>>
 */
public ArrayList<ArrayList<String>> selectRecordsFromDBList(String tableName, String[] tableColumns,String whereClase, String whereArgs[], String groupBy,String having, String orderBy)
{       

    ArrayList<ArrayList<String>> retList = new ArrayList<ArrayList<String>>();
      ArrayList<String> list = new ArrayList<String>();
      Cursor cursor = myDataBase.query(tableName, tableColumns, whereClase, whereArgs,
                groupBy, having, orderBy);        
      if (cursor.moveToFirst()) 
      {
         do 
            {
             list = new ArrayList<String>();
             for(int i=0; i<cursor.getColumnCount(); i++)
             {                   
               list.add( cursor.getString(i) );
             }   
             retList.add(list);
         } while (cursor.moveToNext());
      }
      if (cursor != null && !cursor.isClosed()) {
         cursor.close();
      }
      return retList;

}   

/**
 * This function used to insert the Record in DB. 
 * @param tableName
 * @param nullColumnHack
 * @param initialValues
 * @return the row ID of the newly inserted row, or -1 if an error occurred
 */
public long insertRecordsInDB(String tableName, String nullColumnHack,ContentValues initialValues) 
{
    return myDataBase.insert(tableName, nullColumnHack, initialValues);
}

/**
 * This function used to update the Record in DB.
 * @param tableName
 * @param initialValues
 * @param whereClause
 * @param whereArgs
 * @return true / false on updating one or more records
 */
public boolean updateRecordInDB(String tableName,ContentValues initialValues, String whereClause, String whereArgs[])
{
    return myDataBase.update(tableName, initialValues, whereClause,whereArgs) > 0;              
}

/**
 * This function used to update the Record in DB.
 * @param tableName
 * @param initialValues
 * @param whereClause
 * @param whereArgs
 * @return 0 in case of failure otherwise return no of row(s) are updated
 */

public int updateRecordsInDB(String tableName,ContentValues initialValues, String whereClause, String whereArgs[])
{
    return myDataBase.update(tableName, initialValues, whereClause, whereArgs);     
}

/**
 * This function used to delete the Record in DB.
 * @param tableName
 * 
 * @param whereClause
 * @param whereArgs
 * @return 0 in case of failure otherwise return no of row(s) are deleted.
 */
public int deleteRecordInDB(String tableName, String whereClause,
        String[] whereArgs) {
    return myDataBase.delete(tableName, whereClause, whereArgs);
}

// --------------------- Select Raw Query Functions ---------------------

/**
 * apply raw Query
 * @param query
 * @param selectionArgs
 * @return Cursor
 */
public Cursor selectRecordsFromDB(String query, String[] selectionArgs) 
{
    return myDataBase.rawQuery(query, selectionArgs);       
}

/**
 * apply raw query and return result in list
 * @param query
 * @param selectionArgs
 * @return ArrayList<ArrayList<String>>
 */
public ArrayList<ArrayList<String>> selectRecordsFromDBList(String query, String[] selectionArgs) 
{         
      ArrayList<ArrayList<String>> retList = new ArrayList<ArrayList<String>>();
      ArrayList<String> list = new ArrayList<String>();
      Cursor cursor = myDataBase.rawQuery(query, selectionArgs);            
      if (cursor.moveToFirst()) {
         do {
             list = new ArrayList<String>();
             for(int i=0; i<cursor.getColumnCount(); i++){                   
                 list.add( cursor.getString(i) );
             }   
             retList.add(list);
         } while (cursor.moveToNext());
      }
      if (cursor != null && !cursor.isClosed()) 
      {
         cursor.close();
      }
      return retList;
   }

}

Answer 1

试试这个，

 // Populating the name to  Spinner
            Cursor cNames = db.function();
            startManagingCursor(cNames);

            // create an array to specify which fields we want to display
            String[] from = new String[] { DBAdapter.KEY_NAME };
            // create an array of the display item we want to bind our data to
            int[] to = new int[] { android.R.id.text1 };

            Spinner spinname =(Spinner)findViewById(R.id.name);
            SimpleCursorAdapter adapter = new SimpleCursorAdapter(this,
                    android.R.layout.simple_spinner_item, cNames, from, to);
            adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
            spinname.setAdapter(adapter);