适配器模式（数据库方面）支持不同的数据库连接

<?php

define("BASDIR",__DIR__);
include BASDIR."/Phpclass/Loader.php";
spl_autoload_register("\\Phpclass\\Loader::autoload_rege");


$mysqli= new \Phpclass\Databases\Mysqlis();

$mysqli->connect("localhost","root","root","nfyx");

$sql="select name from test where id>0";
$res=$mysqli->query($sql);


foreach ($res as $row)
{
 echo $row['name']."\n";
}

$mysqli->close();

$mysqli= new \Phpclass\Databases\PDOS();

$mysqli->connect("localhost","root","root","nfyx");

$sql="select name from test where id>0";
foreach ($mysqli->query($sql,PDO::FETCH_ASSOC) as $row)
 {
 print_r($row);
 }

$mysqli->close();
-------------------------------------------------------------------Index2.php

<?php

namespace Phpclass\Databases;
use mysqli;

class Mysqlis implements \Phpclass\IDatabase
{
 static protected $conn;
 function connect($host, $user, $passwd, $db)
 {
 self::$conn = new mysqli($host,$user,$passwd,$db);

 if (self::$conn->connect_errno)
 {
 die("连接数据库失败".self::$conn->connect_error);
 }
 }

 function query($sql)
 {
 return self::$conn->query($sql);
 }
 function close()
 {
 self::$conn=null;
 }

}

-------------------------------------------------------------------Mysqlis.php

<?php
namespace Phpclass\Databases;
use PDO;

class PDOS implements \Phpclass\IDatabase
{
 static protected $conn;
 function connect($host, $user, $passwd, $db)
 {
 try {

 self::$conn = new PDO("mysql:host=$host;dbname=$db", $user, $passwd);

 } catch (PDOException $e) {
 echo 'Connection failed: ' . $e->getMessage();
 }
 }

 function query($sql)
 {
 return self::$conn->query($sql);
 }
 function close()
 {
 self::$conn=null;
 }

}

-------------------------------------------------------------------PDOS.php