interface:
//JDBC:
public java.sql.Connection getConnection() throws java.sql.SQLException;
public void releaseResource() throws java.sql.SQLException;

//JNDI
public javax.sql.DataSource getDataSource() throws java.sqlSQLException,javax.naming.NameingException;

------解决方案--------------------
使用数据库连接池
http://qushaoyan.javaeye.com/blog/774982

------解决方案--------------------
直接用应用的连接池

------解决方案--------------------
JdbC或者数据源 dataSource

------解决方案--------------------
import java.sql.Connection;

public class DBConnection{
  private String driver="oracle.jdbc.driver.OracleDriver";
  private String url="";
  private String username="";
  private String password="";
  Connection conn=null

public static Connection getConn(){
   try{
   Class.forName(driver);
   conn=DriverManager.getConnection(url,username,password);
   }catch(Exception e){
	e.printStackTrace();
   }
   return conn;
  }
}

public void close(){
  if(conn!=null)
  {
   try{
     conn.close();
   }catch(Exception e){
        e.printStackTrace();
   }
  }
}

以上是比较简单的数据库连接，