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();
        }
    
    
    } 
 

    public  synchronized static JDBCUtil getPool()
    {
     if (pool == null) {
             pool=new JDBCUtil();
         }
     return pool;
    }

    public synchronized Connection getConnection() throws  SQLException {
       
        Connection conn = null;
        if (dataSource != null) {
            conn = dataSource.getConnection();
        }
        return conn;
    }

}

[解决办法]
LZ可以将其定义到配置文件中，启动后，这里的IP使用配置文件配置的IP