package  com.mycompany;

 public   class  MySuperUtils{
   public  Connection getConnection()  throws  Exception {
        Context initContext =  new  InitialContext();
        Context envContext = (Context) initContext.lookup("java:/comp/env");
        DataSource ds = (DataSource) envContext.lookup("jdbc/YOUR_DEF");
        Connection conn = ds.getConnection();
         return  conn;
    }
}

function....() ...{
   Connection conn =  new  MySuperUtils().getConnection();
}

"Data source rejected establishment of connection,  message from server: \"Too many connections\"

    <Resource
      name="jdbc/TestDB"
      type="javax.sql.DataSource"
      factory="org.apache.commons.dbcp.BasicDataSourceFactory"
      password="pass"
      driverClassName="com.mysql.jdbc.Driver"
      removeAbandoned="true"
      removeAbandonedTimeout="60"
      logAbandoned="true"
      maxIdle="300"
      maxWait="10000"
      initialSize="10"
      validationQuery="select * from foo"
      username="user"
      url="jdbc:mysql://localhost:3306/testDB"
      maxActive="1400"/>