JDBC-Verbindung mit auto-reconnect

Selbst wenn Sie JDBC connection pool application-server oder apache-commons-pooling, lohnt es sich, code " retry-Logik. Basierend auf der Konfiguration Ihres Applikations-server, app-server entfernen alle zusammengefassten verbindungen und erstellen Sie eine neue Reihe von verbindungen. Hier ist ein Beispiel:

Connection conn = null;
Statement stmt = null;
ResultSet rs = null;
//
//How many times do you want to retry the transaction
//(or at least _getting_ a connection)?
//
int retryCount = 5;
boolean transactionCompleted = false;
do {

  try {
    conn = getConnection(); //assume getting this from a
    //javax.sql.DataSource, or the
    //java.sql.DriverManager

    retryCount = 0;
    stmt = conn.createStatement();
    String query = "Some sample SQL";
    rs = stmt.executeQuery(query);
    while (rs.next()) {
    }
    rs.close();
    rs = null;
    stmt.close();
    stmt = null;

    conn.close();
    conn = null;
    transactionCompleted = true;
  } catch (SQLException sqlEx) {
    //
    //The two SQL states that are 'retry-able' 
    //for a communications error.
    //
    //Only retry if the error was due to a stale connection,
    //communications problem 
    //
    String sqlState = sqlEx.getSQLState();
    if ("Substitute with Your DB documented sqlstate number for stale connection".equals(sqlState) ) {
      retryCount--;
    } else {
      retryCount = 0;
    }
  } finally {
    if (rs != null) {
      try {
        rs.close();
      } catch (SQLException sqlEx) {
        //log this
      }
    }
    if (stmt != null) {
      try {
        stmt.close();
      } catch (SQLException sqlEx) {
        //log this
      }
    }
    if (conn != null) {
      try {
        //
        //If we got here, and conn is not null, the
        //transaction should be rolled back, as not
        //all work has been done
        try {
          conn.rollback();
        } finally {

          conn.close();
        }
      } catch (SQLException sqlEx) {
        //
        //If we got an exception here, something
        //pretty serious is going on, so we better
        //pass it up the stack, rather than just
        //logging it. . .
        throw sqlEx;
      }
    }
  }
} while (!transactionCompleted && (retryCount > 0));