单例实例化的有关问题，求指教，求帮助

单例实例化的问题，求指教，求帮助！
下面是我写的代码，标红色的localhost是我要改的地方，我想在第一次实例化JDBCUtil的时候就获取到一个ip地址然后改掉那个localhost，有什么办法吗？求指教！！！

package exam.client.util;


import java.sql.SQLException;

import java.sql.Connection;

import java.util.Properties; 

import org.apache.commons.dbcp.BasicDataSource;

import org.apache.commons.dbcp.BasicDataSourceFactory;


public class JDBCUtil 

{


	    private static BasicDataSource dataSource = null;

	    private static JDBCUtil  pool=null;

	    

	    private JDBCUtil() 

	    {

	     try {

	        Properties p = new Properties();

	        p.setProperty("driverClassName", "com.mysql.jdbc.Driver");

	        p.setProperty("url", "jdbc:mysql://localhost:3306/exam?characterEncoding=gb2312");

	       p.setProperty("password", "root");

	        p.setProperty("username", "root");

	        //p.setProperty("driverClassName", "sun.jdbc.odbc.JdbcOdbcDriver");access

	        //p.setProperty("url", "jdbc:odbc:Myexam");access

	        p.setProperty("maxActive", "30");

	        p.setProperty("maxIdle", "10");

	        p.setProperty("maxWait", "1000");

	        p.setProperty("removeAbandoned", "true");

	        p.setProperty("removeAbandonedTimeout", "120");

	        p.setProperty("testOnBorrow", "true");

	        p.setProperty("logAbandoned", "true");

	        p.setProperty("initialSize", "20");

	        

	        dataSource = (BasicDataSource) BasicDataSourceFactory.createDataSource(p);

	     

	        } catch (Exception e) {

	            e.printStackTrace();

	        }

	    

	    

	    }