Java JDBC connection status
Nothing. Just execute your query. If the connection has died, either your JDBC driver will reconnect (if it supports it, and you enabled it in your connection string—most don’t support it) or else you’ll get an exception.
If you check the connection is up, it might fall over before you actually execute your query, so you gain absolutely nothing by checking.
That said, a lot of connection pools validate a connection by doing something like SELECT 1 before handing connections out. But this is nothing more than just executing a query, so you might just as well execute your business query.
Solution 2
Your best chance is to just perform a simple query against one table, e.g.:
Oh, I just saw there is a new method available since 1.6:
Returns true if the connection has not been closed and is still valid. The driver shall submit a query on the connection or use some other mechanism that positively verifies the connection is still valid when this method is called. The query submitted by the driver to validate the connection shall be executed in the context of the current transaction.
Solution 3
Use Connection.isClosed() function.
Retrieves whether this Connection object has been closed. A connection is closed if the method close has been called on it or if certain fatal errors have occurred. This method is guaranteed to return true only when it is called after the method Connection.close has been called.
Solution 4
public boolean isDbConnected(Connection con) < try < return con != null && !con.isClosed(); >catch (SQLException ignored) <> return false; > Solution 5
public static boolean isDbConnected() < final String CHECK_SQL_QUERY = "SELECT 1"; boolean isConnected = false; try < final PreparedStatement statement = db.prepareStatement(CHECK_SQL_QUERY); isConnected = true; >catch (SQLException | NullPointerException e) < // handle SQL error here! >return isConnected; > I have not tested with other databases. Hope this is helpful.