无法从assets文件夹复制预先创建的sqlite DB

Question

我有一个预先填充的sqlite数据库，我已经在SQLiteStudio中创建并放入assets /目录。我尝试使用扩展SQLiteOpenHelper的DataBaseHelper将其复制到根存储中。

DataBaseHelper.java

private static String DBPATH = null;
private static String DBNAME = "test.sqlite";

private Context context;
private SQLiteDatabase db;

public DataBaseHelper(Context context) {

    super(context, DBNAME, null, 1);

    if (Build.VERSION.SDK_INT >= 17) {
        DBPATH = context.getApplicationInfo().dataDir + "/databases/";
    } else {
        DBPATH = "/data/data/" + context.getPackageName() + "/databases/";
    }

    this.context = context;
}

@Override
public void onCreate(SQLiteDatabase db) {}

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

private boolean checkDataBase() {
    File dbFile = context.getDatabasePath(DBNAME);
    Log.v(TAG, "checkDataBase() - " + dbFile + "   "+ dbFile.exists());
    return dbFile.exists();
}

public void createDataBase()
        throws Exception {

    boolean exists = checkDataBase();

    if(!exists) {
        this.getReadableDatabase();
        this.close();

        try {
            copyDatabase();
            Log.e(TAG, "createDatabase() - database created");
        } catch (IOException e) {
            throw new Error("Cannot copy file");
        }

    }
}

private void copyDatabase()
        throws IOException {

    String path = DBPATH + DBNAME;

    OutputStream dbStream = new FileOutputStream(context.getDatabasePath(DBNAME));

    InputStream dbInputStream =
            context.getAssets().open(DBNAME);

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

    dbInputStream.close();

    dbStream.flush();
    dbStream.close();
}

public boolean openDataBase() throws SQLException
{
    String path = DBPATH + DBNAME;
    db = SQLiteDatabase.openDatabase(path, null, SQLiteDatabase.CREATE_IF_NECESSARY);
    return db != null;
}

@Override
public synchronized void close()
{
    if(db != null)
        db.close();
    super.close();
}

DataSource.java

private final Context context;
private SQLiteDatabase db;
private DataBaseHelper dbHelper;

public DataSource(Context context) {
    this.context = context;
    dbHelper = new DataBaseHelper(context);
}

public DataSource createDatabase() throws SQLException {
    try {
        dbHelper.createDataBase();
    }
    catch (Exception e) {
        Log.e(TAG, e.toString() + "  UnableToCreateDatabase");
        throw new Error("UnableToCreateDatabase");
    }
    return this;
}

public DataSource open() throws SQLException {
    try {
        dbHelper.openDataBase();
        db = dbHelper.getReadableDatabase();
    }
    catch (SQLException mSQLException) {
        Log.e(TAG, "open >>"+ mSQLException.toString());
        throw mSQLException;
    }
    return this;
}

public void close() {
    dbHelper.close();
}

public List<String> listAllProducts() {
    List<String> result = new ArrayList<String>();
    try {
        String MY_QUERY = ""
                + "SELECT Upper(prd_name) AS name "
                + "FROM   products "
                + "WHERE  prd_type = 'A' "
                + "ORDER  BY name ASC";

        Cursor cursor = db.rawQuery(MY_QUERY, null);

        cursor.moveToFirst();
        while (!cursor.isAfterLast()) {
            result.add(cursor.getString(cursor.getColumnIndex("nome")));

            cursor.moveToNext();
        }

        cursor.close();
    } catch (Exception sqle) {
        Log.e(TAG, "listAllProducts() >>"+ sqle.getMessage());
    }
    return result;
}

主要活动

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

    String[] array = null;
    try {
        DataSource ds = new DataSource(this);
        ds.createDatabase();
        ds.open();

        List<String> items = ds.listAllProducts();
        array = items.toArray(new String[items.size()]);
        Log.i("ITEMS", Arrays.toString(array));
        ds.close();
    } catch (SQLException sql) {
        Log.e("MAIN >>", sql.getMessage());
    }
}

logcat的

    com.test.myapp E/AndroidRuntime: FATAL EXCEPTION: main
 java.lang.Error: Cannot copy file
     at com.test.myapp.db.DataBaseHelper.createDataBase(DataBaseHelper.java:106)
     at com.test.myapp.db.DataSource.createDatabase(DataSource.java:30)
     at com.test.myapp.MainActivity.onCreate(MainActivity.java:33)
     at android.app.Activity.performCreate(Activity.java:5133)
     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2175)
     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
     at android.app.ActivityThread.access$600(ActivityThread.java:141)
     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
     at android.os.Handler.dispatchMessage(Handler.java:99)
     at android.os.Looper.loop(Looper.java:137)
     at android.app.ActivityThread.main(ActivityThread.java:5103)
     at java.lang.reflect.Method.invokeNative(Native Method)
     at java.lang.reflect.Method.invoke(Method.java:525)
     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
     at dalvik.system.NativeStart.main(Native Method)

我该如何解决？ 感谢