Connecting GWT and PostgreSQL - google-app-engine

Question

I've been working with GWT and appengine. Now I want to change my database to a relational one. I prefer PostgreSQL over MySQL because of the schema architecture.
I already work in projects with JDBC, but I cannot make it work in my appengine project.
What am I doing wrong?

Answer 1

I think you are mistake. If you want your backend to connect to JDBC you have to disable appengine.
I recommend creating a new web project with the google eclipse plugin but without appengine. Then copy all the source files and start from there.
I let you my class to connect to PostgreSQL vua JDBC
public class ConexionBD
{
private Vector <Connection> connections = new Vector<Connection>();
protected int cantCon=3;
private static ConexionBD pool;
private ConexionBD(){
for (int i= 0; i< cantCon;i++)
connections.add(connect());
}
public static ConexionBD getPoolConnection(){
if (pool== null)
pool =new ConexionBD();
return pool;
}
private Connection connect()
{
try
{
//Setear driver
Class.forName ("org.postgresql.Driver").newInstance ();
Connection con = DriverManager.getConnection ("jdbc:postgresql://localhost:5432/llevomisnegocios","postgres","root");
return con;
}
catch (SQLException e){
System.out.println("Mensaje Error al Conectar: " + e.getMessage());
//System.out.println("Stack Trace: " + e.getStackTrace());
return null;
}catch (Exception ex){
System.out.println("Mensaje Error al Conectar: " + ex.getMessage());
//System.out.println("Stack Trace: " + ex.getStackTrace());
return null;
}
}
public void closeConnections(){
for (int i=0; i<connections.size();i++)
{
try
{
connections.elementAt(i).close();
}
catch(Exception e)
{
System.out.println("Mensaje Error: " + e.getMessage());
System.out.println("Stack Trace: " + e.getStackTrace());
}
}
}
public Connection getConnection(){
Connection c = null;
if (connections.size()>0)
c = connections.remove(0);
else{
c = connect();
System.out.println("PoolConnection: Conexion Exitosa con la BD");
}
return c;
}
public void realeaseConnection(Connection c){
connections.add(c);
}
}