DBWrapper.java

public <T> T execute(Function<DSLContext,T> fun) {

    T result = null;
    Connection connection = null;
    DatabaseException userException = null;

    try {

      connection = dataSource.getConnection();
      connection.setAutoCommit(false);
      DSLContext ctx = DSL.using(connection, dialect, settings);

      try {

        result = fun.apply(ctx);

      } catch (Exception e) {

        String msg;

        if (e instanceof DataAccessException) {

          msg = e.getCause().getMessage();

          if (e.getCause() instanceof SQLIntegrityConstraintViolationException) {

            SQLIntegrityConstraintViolationException ve = (SQLIntegrityConstraintViolationException) e.getCause();

            if (ve.getErrorCode() == 1062) { // http://dev.mysql.com/doc/refman/5.7/en/error-messages-server.html#error_er_dup_key
              String template = "Duplicate entry '(.*)' for key '(.*)'";
              Pattern pattern = Pattern.compile(template);
              Matcher matcher = pattern.matcher(ve.getMessage());
              if (matcher.matches()) {
                String key = matcher.group(1);
                String value = matcher.group(2);
                userException = new DuplicateKeyException(msg, key, value);
              }
            }
          }

        } else {
          msg = e.getMessage();
        }

        log.error(msg);

        if (userException == null) {
          userException = new DatabaseException(msg);
        }

        if (!connection.isClosed()) {
          connection.rollback();
        }

      }

      if (null == userException) {
        connection.commit();
      }

    } catch (SQLException e) {
      throw new DatabaseException(e.getMessage());
    } finally {

      try {

        // Release the connection back to the pool

        if (null != connection && !connection.isClosed()) {
          connection.close();
        }

      } catch (SQLException e) {
        throw new DatabaseException(e.getMessage());
      }

    }

    if (userException != null) {
      throw userException;
    } else {
      return result;
    }
  }