Question

您好我正在尝试在我的应用中使用预装数据库。但是当我运行应用程序时，它会给出错误

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

我的数据库帮助程序类是：

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

步骤1：摆脱以下几行：

public SQLiteDatabase dbSqlite;
private final Context myContext;

第2步：更改getCursor()以致电getReadableDatabase()，而不是引用现已删除的dbSqlite。

步骤3：删除引用dbSqlite或myContext的所有其他方法。

步骤4：删除DATABASE_PATH（不要硬编码路径）。

第5步：删除createDB()，createDatabase()，DbExists()和copyDataBase()方法。如果您希望尝试使用自己的应用发布数据库，请考虑使用SQLiteAssetHelper。

SQLiteException：无法打开数据库文件

1 个答案: