Connection conn=null;
try {
  Class.forName("com.mysql.jdbc.Driver",
                true, Thread.currentThread().getContextClassLoader());
  conn=DriverManager.getConnection("jdbc:mysql://dbserver?user=dolly&password=dagger");
  /* use the connection here */
  c.close();
} 
catch(Exception e) {
  e.printStackTrace();
} 
finally {
  if(conn!=null) {
    try {
      conn.close();
    } catch(SQLException e) {}
  }
}

Connection conn=null;
try {
  Context ctx=new InitialContext();
  Object datasourceRef=ctx.lookup("java:comp/env/jdbc/mydatasource");
  DataSource ds=(Datasource)datasourceRef;
  Connection c=ds.getConnection();
  /* use the connection */
  c.close();
} 
catch(Exception e) {
  e.printStackTrace();
} 
finally {
  if(conn!=null) {
    try {
      conn.close();
    } catch(SQLException e) { }
  }
}