android - 从 Assets 文件夹错误读取sqlite

Question

我的Databasehelper.class

public class DatabaseHelper extends SQLiteOpenHelper {
    public static final String DBNAME = "db3000.sqlite";
    public static final String DBLOCATION = "/data/data/com.gnirt69.sqlitefromassetexample/databases/";
    private Context mContext;
    private SQLiteDatabase mDatabase;

    public DatabaseHelper(Context context) {
        super(context, DBNAME, null, 1);
        this.mContext = context;
    }

    @Override
    public void onCreate(SQLiteDatabase db) {

    }

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

    }

    public void openDatabase() {
        String dbPath = mContext.getDatabasePath(DBNAME).getPath();
        if(mDatabase != null && mDatabase.isOpen()) {
            return;
        }
        mDatabase = SQLiteDatabase.openDatabase(dbPath, null, SQLiteDatabase.OPEN_READWRITE);
    }

    public void closeDatabase() {
        if(mDatabase!=null) {
            mDatabase.close();
        }
    }
public ArrayList<word> getListWord() {
        word product = null;
        ArrayList<word> productList = new ArrayList<>();
        openDatabase();
        Cursor cursor = mDatabase.rawQuery("SELECT * FROM word", null);
        cursor.moveToFirst();
        while (!cursor.isAfterLast()) {
            product = new word(cursor.getInt(0), cursor.getString(1), cursor.getString(2), cursor.getString(3),cursor.getString(4),cursor.getInt(5));
            productList.add(product);
            cursor.moveToNext();
        }
        cursor.close();
        closeDatabase();
        return productList;
    }
}

我的 framgnet.class

 @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        mDBHelper = new DatabaseHelper(getActivity());

        //Check exists database
        File database = getActivity().getDatabasePath(DatabaseHelper.DBNAME);
        if(false == database.exists()) {
            mDBHelper.getReadableDatabase();
            //Copy db
            if(copyDatabase(getActivity())) {
                Toast.makeText(getActivity(), "Copy database succes", Toast.LENGTH_SHORT).show();
            } else {
                Toast.makeText(getActivity(), "Copy data error", Toast.LENGTH_SHORT).show();
                return;
            }
        }
//        Get product list in db when db exists
        mProductList = mDBHelper.getListWord();
       // getCategoryFromDataBase();

    }

private boolean copyDatabase(Context context) {
        try {

            InputStream inputStream = context.getAssets().open(DatabaseHelper.DBNAME);
            String outFileName = DatabaseHelper.DBLOCATION + DatabaseHelper.DBNAME;
            OutputStream outputStream = new FileOutputStream(outFileName);
            byte[]buff = new byte[1024];
            int length = 0;
            while ((length = inputStream.read(buff)) > 0) {
                outputStream.write(buff, 0, length);
            }
            outputStream.flush();
            outputStream.close();
            Log.w("MainActivity","DB copied");
            return true;
        }catch (Exception e) {
            e.printStackTrace();
            return false;
        }
    }

最初，我尝试在Activity.class中调用读取数据；它运行良好，但是当我在 Fragment 中尝试它时，它不会运行和显示

java.io.FileNotFoundException: /data/data/com.gnirt69.sqlitefromassetexample/databases/db3000.sqlite: open failed: EACCES (Permission denied)

这里发生了什么？
请帮助我。

Answer 1

您需要在 list 文件中添加以下权限

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />