SQLiteDatabase填充spinner（populating spinner from SQLiteDatabase）

1. 按行读取assets下txt数据，并初始化到SQLiteDatabase

1. 进入project下，右击main创建assets文件夹，添加txt文件

2. 在SQLiteOpenHelper下：

(1) 写读取txt并插入数据库的方法：readFromAssets(SQLiteDatabase db) 并在onCreate( )里调用.

(2) getAllNation()用于之后获取数据库数据填充spinner

public class DBManager {
    // Database Version
    private static final int DATABASE_VERSION = 1;
    // Database Name
    private static final String DATABASE_NAME = "users.db";
    private final Context context;

    private static final String SQL_CREATE_ENTRIES =
            "CREATE TABLE " + NationalityDBStructure.tableEntry.TABLE_NAME + " (" +
                    " _id INTEGER PRIMARY KEY AUTOINCREMENT, " +
                    NationalityDBStructure.tableEntry.COLUMN_NAME +
                    " )";

    private static final String SQL_DELETE_ENTRIES =
            "DROP TABLE IF EXISTS " + NationalityDBStructure.tableEntry.TABLE_NAME;

    private NationalityOpenHelper myDBHelper;
    private SQLiteDatabase db;

    private String[] projection = {
            NationalityDBStructure.tableEntry.COLUMN_NAME};

    // we can obtain a reference to it and call it
    // in the DBManager constructor
    public DBManager(Context ctx) {
        this.context = ctx;
        myDBHelper = new NationalityOpenHelper(context);
    }

    // open db
    public DBManager open() throws SQLException {
        db = myDBHelper.getWritableDatabase();
        return this;
    }
    // close db
    public void close() {
        myDBHelper.close();
    }

    /**
     * 2. Getting all labels
     * returns list of labels
     * */
    public List<String> getAllNation(){
        List<String> labels = new ArrayList<String>();

//        SQLiteDatabase db = myDBHelper.getReadableDatabase();
        Cursor cursor = db.query(NationalityDBStructure.tableEntry.TABLE_NAME, projection, null, null,
                null, null, null);

        // looping through all rows and adding to list
        if (cursor.moveToFirst()) {
            do {
                //add first entry into labels
                labels.add(cursor.getString(0));
            } while (cursor.moveToNext());
        }

        // closing connection
        cursor.close();
        db.close();

        // returning lables
        return labels;
    }

    private class NationalityOpenHelper extends SQLiteOpenHelper {


        public NationalityOpenHelper(Context context){
            super(context, DATABASE_NAME, null, DATABASE_VERSION);
        }
	// 1. this method
        private void readFromAssets(SQLiteDatabase db) {
            try {
                ContentValues values = new ContentValues();
                InputStream is = context.getAssets().open("nationdata.txt");
                InputStreamReader reader = new InputStreamReader(is);
                BufferedReader br = new BufferedReader(reader);
                String s1;

                while ((s1 = br.readLine()) != null) {
                    //添加记录
                    values.put(NationalityDBStructure.tableEntry.COLUMN_NAME, s1);
                    //调用insert()方法插入数据
                    db.insert(NationalityDBStructure.tableEntry.TABLE_NAME, null, values);
                }
                br.close();
                reader.close();
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }

        @Override
        public void onCreate(SQLiteDatabase db){
            db.execSQL(SQL_CREATE_ENTRIES);

	    // call it here
            readFromAssets(db);
        }

        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion){
            // This database is only a cache for online data, so its upgrade policy is
	// to simply to discard the data and start over
            db.execSQL(SQL_DELETE_ENTRIES);
            onCreate(db);
        }
        public void onDowngrade(SQLiteDatabase db, int oldVersion, int newVersion) {
            onUpgrade(db, oldVersion, newVersion);
        }
    }
}

2. populating spinner from SQLiteDatabase（数据库数据填充spinner）

public class RegisterActivity extends AppCompatActivity implements AdapterView.OnItemSelectedListener {

    protected DBManager dbManager;
    Spinner msp_nation;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_register);

        dbManager = new DBManager(this);

        // Spinner element
        msp_nation = (Spinner) findViewById(R.id.sp_nationality);
        mtv_showDoB = (TextView) findViewById(R.id.tv_showDoB);
        mtv_login = (TextView) findViewById(R.id.tv_login);

        // Spinner click listener
        msp_nation.setOnItemSelectedListener(this);

        // Loading spinner data from database
        loadSpinnerData();


    }
   
    /**
     * Function to load the spinner data from SQLite database
     * */
    public void loadSpinnerData(){

	// 第一次open()会初始化数据库（调用onCreate()）
        try {
            dbManager.open();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        // Spinner Drop down elements
        List<String> lables = dbManager.getAllNation();

        // Creating adapter for spinner
        ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(this,
                android.R.layout.simple_spinner_item, lables);

        // Drop down layout style - list view with radio button
        dataAdapter
                .setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

        // attaching data adapter to spinner
        msp_nation.setAdapter(dataAdapter);

        dbManager.close();
    }

    //    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int position,
                               long id) {
        // On selecting a spinner item
        String label = parent.getItemAtPosition(position).toString();

        // Showing selected spinner item
        Toast.makeText(parent.getContext(), "You selected: " + label,
                Toast.LENGTH_LONG).show();

    }
    //    @Override
    public void onNothingSelected(AdapterView<?> arg0) {
        // TODO Auto-generated method stub

    }
}

效果：