SQLiteException：无法打开数据库文件

Question

Hi I am trying to use preloaded database in my app. but when I am run the app it will give the error

sqlite3_open_v2("/data/data/com.example.preloaddatabase/databases/ingredients.db", &handle, 2, NULL) failed

ERROR IN CODE :android.database.sqlite.SQLiteException: unable to open database file

And My Database Helper Class is:

class IngredientHelper extends SQLiteOpenHelper {
    private static final String DATABASE_PATH = "/data/data/com.example.preloaddatabase/databases/";
    private static final String DATABASE_NAME = "ingredients.db";

    private static final String TABLE_NAME = "Ingredients";
    private static final String COLUMN_ID = "_id";
    private static final String COLUMN_TITLE = "ingredient_name";

    private static final int SCHEMA_VERSION = 1;

    public SQLiteDatabase dbSqlite;
    private final Context myContext;

    public IngredientHelper(Context context) {
        super(context, DATABASE_NAME, null, SCHEMA_VERSION);
        this.myContext = context;
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("Create Table Ingredients(_id INTEGER PRIMARY KEY,ingredient_name TEXT)");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {}

    public void createDatabase() {
        createDB();
    }

    public void createDB() {
        boolean dbExist = DbExists();
        if (dbExist) {
            this.getReadableDatabase();
            copyDataBase();
        }
    }

    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 copyDataBase() {
        InputStream iStream = null;
        OutputStream oStream = null;
        String outFilePath = DATABASE_PATH + DATABASE_NAME;
        try {
            iStream = myContext.getAssets().open(DATABASE_NAME);
            oStream = new FileOutputStream(outFilePath);
            byte[] buffer = new byte[2048];
            int length;
            while ((length = iStream.read(buffer)) > 0) {
                oStream.write(buffer, 0, length);
            }
            oStream.flush();
            oStream.close();
            iStream.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();
    }

    public Cursor getCursor() {
        SQLiteQueryBuilder queryBuilder = new SQLiteQueryBuilder();
        queryBuilder.setTables(TABLE_NAME);
        String[] asColumnsToReturn = new String[] { COLUMN_ID, COLUMN_TITLE };

        Cursor mCursor = queryBuilder.query(dbSqlite, asColumnsToReturn,
                null, null, null, null, "ingredient_name ASC");
        return mCursor;
    }

    public String getName(Cursor c) {
        return (c.getString(1));
    }
}

Answer 1

Step #1: Get rid of the following lines:

public SQLiteDatabase dbSqlite;
private final Context myContext;

Step #2: Change getCursor() to call getReadableDatabase() instead of referencing the now-removed dbSqlite .

Step #3: Delete all other methods that refer to dbSqlite or myContext .

Step #4: Delete DATABASE_PATH (do not hardcode paths).

Step #5: Delete the createDB() , createDatabase() , DbExists() , and copyDataBase() methods. If you wish to try to ship a database with your app, consider using SQLiteAssetHelper .