Get JDBC Connection location

Question

What is the best way to connect to a database in Java Class?
I have used 3 different ways and would like to know what is the most efficient one.
1- Put the connection as a data member:
public class DatabaseHelperClass {     private Connection connection = new DbConnectionManager().getConnection();         public void insertDb(DbBean db) throws SQLException  {     PreparedStatement stmt = connection.prepareStatement("insert ..");     ...     }   public void updateDb(DbBean db) throws SQLException  {     PreparedStatement stmt = connection.prepareStatement("update ..");     ...     }
2 - Put connection in Constructor:
public class DatabaseHelperClass {     public DatabaseHelperClass() {     Connection connection = new DbConnectionManager().getConnection();     }         public void insertDb(DbBean db) throws SQLException  {     PreparedStatement stmt = connection.prepareStatement("insert ..");     ...     }     public void updateDb(DbBean db) throws SQLException  {     PreparedStatement stmt = connection.prepareStatement("update ..");     ...     }
3- Put connection in every method that needs a connection:
public class DatabaseHelperClass {     public void insertDb(DbBean db) throws SQLException  {     Connection connection = new DbConnectionManager().getConnection();     PreparedStatement stmt = connection.prepareStatement("insert ..");     ...     } public void updateDb(DbBean db) throws SQLException  {     Connection connection = new DbConnectionManager().getConnection();     PreparedStatement stmt = connection.prepareStatement("update ..");     ...     }

Answer 1

I normally use connection per thread with a connection pool. And connection is released with every commit and rollback. And never call connection.commit()/rollback/close directly I use a separate database manager class for it.
public class ConnectionMgr{
ThreadLocal connecition = new ThreadLocal();
public static Connection getConnection(){
   Connection c = (Connection)connecition.get();
   if(c == null){
      c = DriverManager.getConnection(....);
      connection.set(c);
   return c;
public static void commit(){
   Connection c = (Connection)connecition.get();
   if(c != null){
      c.commit();
      close();
public static void rollback(){
   Connection c = (Connection)connecition.get();
   if(c != null){
      c.rollback();
      close();
public static void close(){
   Connection c = (Connection)connecition.get();
   if(c != null){
      c.close();
      connection.set(null);
}Code in a data access method looks like
public void someMethod(){
  Statement s = ConnectionMgr.getConnection().createStatement();
  s.executeUpdate(".....");
  ConnectionMgr.commit();
}