Java JDBC connection status

Question

I am  successfully  connecting to a database using the following   java sql Connection connect   DriverManager getConnection     jdbc mysql   localhost some database user some user amp password some password      What should I be checking to see if the connection is still open and up after some time  I was hoping for something like connect isConnected    available for me to use

User · Answer

Your best chance is to just perform a simple query against one table, e.g.:

select 1 from SOME_TABLE;

Oh, I just saw there is a new method available since 1.6:

java.sql.Connection.isValid(int timeoutSeconds):

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.

User · Answer

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

User · Answer

Use Connection isClosed   function   The JavaDoc states      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

User · Answer

You also can use public boolean isDbConnected Connection con        try           return con    null  amp  amp   con isClosed          catch  SQLException ignored          return false

User · Answer

If you are using MySQL  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

User · Answer

The low-cost method  regardless of the vendor implementation  would be to select something from the process memory or the server memory  like the DB version or the name of the current database  IsClosed is very poorly implemented   Example   java sql Connection conn    lt connect procedure gt   conn close    try     conn getMetaData      catch  Exception e      System out println  Connection is closed

[java] Java JDBC connection status

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