asked on

Disconnecting from DB after getting data

There are two classes:

public class ConnectDB {

    private static String databaseurl = "jdbc:oracle:thin:@10.1.1.7:1521:orcl";
    private static String user = "LIONFX";
    private static String password = "";
    private static String driverName = "oracle.jdbc.OracleDriver";
    
    Connection conn;
    ResultSet rs;
    Statement statement;
    PreparedStatement ps;

    public void insert(String sql) throws SQLException {
        try {
            Class.forName(driverName).newInstance();
            conn = (Connection) DriverManager.getConnection(databaseurl, user, password);
            statement = (Statement) conn.createStatement();
            int st = statement.executeUpdate(sql);
            destroy(conn);
            statement.close();

        } catch (InstantiationException e) {
        } catch (IllegalAccessException e) {
        } catch (ClassNotFoundException e) {
        }
    }

    public ResultSet select(String sql) throws SQLException, ClassNotFoundException, InstantiationException, IllegalAccessException {
        Class.forName(driverName).newInstance();
        conn = (Connection) DriverManager.getConnection(databaseurl, user, password);
        ps = conn.prepareStatement(sql);
        rs = ps.executeQuery();
//        destroy(conn);
        return rs;
    }

    public void destroy(Connection conn) {
        try {
            conn.close();
        } catch (SQLException e) {
        }
    }

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which connecting to DB
and SelectData which extract data from this DB:

public class SelectData extends TimerTask {

      private ConnectDB conn = new ConnectDB();
      String symbol[] = new String[3];
      double openBid[] = new double[3];
      double openAsk[] = new double[3];
      Timestamp timest[] = new Timestamp[3];

      public void run() {
            try {

      ResultSet rs = conn.select("SELECT * FROM EURUSD_1C where timest = ( select max( timest ) from EURUSD_1C ) and rownum = 1 union all "
                                          + "SELECT * FROM EURJPY_1C where timest = ( select max( timest ) from EURJPY_1C ) and rownum = 1  union all "
                                          + "SELECT * FROM USDJPY_1C where timest = ( select max( timest ) from USDJPY_1C ) and rownum = 1");

                  while (rs.next()) {

                        if (rs.getString("SYMBOL").equals("EUR/USD")) {
                              symbol[0] = rs.getString("SYMBOL");
                              timest[0] = rs.getTimestamp("TIMEST");
                              openBid[0] = rs.getDouble("BIDPX");
                              openAsk[0] = rs.getDouble("ASKPX");

                        } else if (rs.getString("SYMBOL").equals("EUR/JPY")) {
                              symbol[1] = rs.getString("SYMBOL");
                              timest[1] = rs.getTimestamp("TIMEST");
                              openBid[1] = rs.getDouble("BIDPX");
                              openAsk[1] = rs.getDouble("ASKPX");

                        } else if (rs.getString("SYMBOL").equals("USD/JPY")) {
                              symbol[2] = rs.getString("SYMBOL");
                              timest[2] = rs.getTimestamp("TIMEST");
                              openBid[2] = rs.getDouble("BIDPX");
                              openAsk[2] = rs.getDouble("ASKPX");

                        }

                        else {
                              System.out.println("No new rows");
                        }
                  }
                  rs.close();
            } catch (Exception ex) {
                  ex.printStackTrace();
            }
      }
}

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For insert method it close sessions well.
The problem is that when ConnectDB connecting to Oracle and get data it doesn't close sessions, and for next query open new session, so in 3 hours it's open all 300 sessions and stack Oracle.
I try to call destroy(conn); like in insert method but when I put it above return rs; I have error - Closed connection.
When I put it after - unreachable statement.
Please advice how to close connection for select method after each session.

Pacane

Isn't there a method called .close() on your connection object?

CEHJ

You need to call ConnectDB.destroy at the end of SelectData.run in a finally block

CEHJ

>>public void destroy(Connection conn) {

The parameter is redundant and you should get rid of it

CEHJ

Or: leave things as they are and uncomment the call to destroy in ConnectDB.select, which you've commented out

gbcbr

ASKER

Please give me more details where to place conn.destroy(conn); into Select Data
because it doesn't accept this statement.

} else if (rs.getString("SYMBOL").equals("USD/JPY")) {
symbol[2] = rs.getString("SYMBOL");
timest[2] = rs.getTimestamp("TIMEST");
openBid[2] = rs.getDouble("BIDPX");
openAsk[2] = rs.getDouble("ASKPX");

conn.destroy((Connection) conn);

java.lang.ClassCastException: lionfx.dbfx.db.ConnectDB cannot be cast to java.sql.Connection
at lionfx.dbfx.db.SelectData.run(SelectData.java:47)
at java.util.TimerThread.mainLoop(Timer.java:512)
at java.util.TimerThread.run(Timer.java:462)

CEHJ

Forget my last comment: it won't work

gbcbr

ASKER

I know, because I try to put this destroy in all places of select, but it doesn't accept anywhere.

ASKER CERTIFIED SOLUTION

CEHJ

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gbcbr

ASKER

Perfect! Thank you very much for the help!

CEHJ