Configuring an Exception Handler

You can associate a single exception handling class with each session. This class must implement the oracle.toplink.exceptions.ExceptionHandler interface.

Table 77-11 summarizes which sessions support exception handler configuration.

Table 77-11 Session Support for Exception Handler Configuration

Session	Using TopLink Workbench	Using Java
Server and Client Sessions
Session Broker and Client Sessions
Database Sessions

For an example exception handler implementation, see "Using Java".

For more information, see "Exception Handlers".

Using TopLink Workbench

To specify the exception handler class in a session, use this procedure:

1. Select a session in the Navigator. Its properties appear in the Editor.

2. Click the Options tab. The Options tab appears.

   Figure 77-6 Options Tab, Exception Handler field

   
   Description of "Figure 77-6 Options Tab, Exception Handler field"
   
   

Click Browse and select the exception handler class for this session.

Using Java

Example 77-6 shows an example exception handler implementation. In this implementation, the exception handler always tries to reestablish the connection if it has been reset by peer, but only retries a query if it is an instance of ReadQuery. Note that this exception handler either returns the result of the reexecuted ReadQuery or throws an exception.

Example 77-6 Implementing an Exception Handler

session.setExceptionHandler(
  new ExceptionHandler()
  {
    public Object handleException(RuntimeException exception)
    {
      if (exception instanceof DatabaseException)
      {
        DatabaseException dbex = (DatabaseException) exception;
        if ((dbex.getInternalException() instanceof SQLException) && 
           (((SQLException) dbex.getInternalException()).getErrorCode() == MyDriver.CONNECTION_RESET_BY_PEER))
        {
           dbex.getAccessor().reestablishConnection(dbex.getSession());
           if (dbex.getQuery() instanceof ReadQuery)
           {
             return dbex.getSession().executeQuery(dbex.getQuery());
           }
           throw exception;
        }
      }
      throw exception;
    }
  }
);

Note: Unhandled exceptions must be rethrown by the exception handler code.