Question

尝试通过从一个类调用连接方法到另一个类来加载已创建的数据库。这是调用连接到db

的方法的GUIClass

public class GUIController implements Initializable {
public void loadImg() throws IOException, Exception {

        try {
            rs = dbc.Story();
            Stage stage = new Stage();
            rs.next();
            fis = rs.getBinaryStream(1);
            BufferedImage imgt = null;
            try {
                imgt = javax.imageio.ImageIO.read(fis);
            } catch (IOException ex) {
                System.out.println("Image failed to load.");
            }

        } catch (SQLException e) {
            System.out.println(e.getMessage());

        }
    }

我在这里连接到数据库

public class DBOperations {

    private Connection connection;
    private Statement statement;
    private PreparedStatement stmnt;

  public ResultSet Story() throws ClassNotFoundException {
        try {
            Class.forName("org.apache.derby.jdbc.ClientDriver");
            String query = "select vista from location where ycoordinate = ? and xcoordinate = ?";

            connection = DriverManager.getConnection("jdbc:derby:" + System.getProperty("user.dir") + "/.." + "/NewGame");
            stmnt = connection.prepareStatement(query);
        int x = 0;
        int y = 0;
        stmnt.setInt(1, y);
        stmnt.setInt(2, x);
        rs =  stmnt.executeQuery();
        } catch (SQLException e) {
            do {
                System.out.println("SQLState:" + e.getSQLState());
                System.out.println("Error Code:" + e.getErrorCode());
                System.out.println("Message:" + e.getMessage());
                Throwable t = e.getCause();
                while (t != null) {
                    System.out.println("Cause:" + t);
                    t = t.getCause();
                }
                e = e.getNextException();
            } while (e != null);
        } catch (IOException ex) {
            Logger.getLogger(DBOperations.class.getName()).log(Level.SEVERE, null, ex);
        }

返回rs; }

我最后得到一个null。

Couldn't open the story C:\Users\Konstantin\Desktop\InteractiveFictionGamePC Imported\NewGame[Ljava.lang.StackTraceElement;@500d4560
null

我认为这可能与我在尝试访问它之前创建NewGame文件夹有关。我有一个现成的数据库，我正在复制，然后运行副本中的所有内容。难道这就是我无法打开数据库的原因吗？我正在运行Java SE 8和最新的Derby。

请帮忙

Derby数据库没有连接，或者数据库文件加载错误 - 空指针？

0 个答案: