Question

这适用于模拟器但不适用于我的手机。至少看起来是这样，因为当我在手机上查询时，它找不到表格。

这是我继承自SQLiteOpenHelper

的类

public class DBHelper extends SQLiteOpenHelper {

private final static String DB_NAME = "klb_db.sqlite";
private final static int DB_VERSION = 1;

private String dbPath;
private Context context;

public DBHelper(Context context) {
    super(context, DB_NAME, null, DB_VERSION);

    this.context = context;
    dbPath = "/" + Environment.getDataDirectory() + "/data/" + context.getPackageName() + "/databases/";
}

public void initializeDatabase() {
    try {
        File file = new File(dbPath + DB_NAME);
        if (!file.exists()) {
            InputStream inputStream = context.getAssets().open(
                    "klb_db.sqlite");
            OutputStream outputStream = new FileOutputStream(file);

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

            inputStream.close();
            outputStream.close();
        }
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
}
}

在dbadapter中，打开方法：

    public DBAdapter open() {
    dbHelper.initializeDatabase();
    db = dbHelper.getWritableDatabase();
    return this;
}

在使用它的活动中：

    @Override
protected void onStart() {
    super.onStart();

    QuizDAO quizDAO = new QuizDAO(this);
    quizDAO.open();
    Cursor cursor = quizDAO.getQuestion(10);
    Toast.makeText(this, cursor.getString(1), Toast.LENGTH_LONG).show();
}

Answer 1

尝试增加你的字节数

byte[] buffer = new byte[1024];

到

byte[] buffer = new byte[2048];

<强> EDITED

@Override
protected void onStart() {
    super.onStart();

    QuizDAO quizDAO = new QuizDAO(this);
    quizDAO.open();
    Cursor cursor = quizDAO.getQuestion(10);
    cursor.moveToFirst()
    Toast.makeText(this, cursor.getString(1), Toast.LENGTH_LONG).show();
}

复制数据库可在模拟器上运行，但不在设备上运行

1 个答案: