php设计模式 适配器模式

适配器模式，可以将截然不同的函数接口封装成统一的API；

应用举例，PHP的数据库操作有Mysql、Mysqli、pdo三种，可以用适配器模式统一成一致，类似的场景还有cache适配器，将memcache、redis，file，apc等不同的缓存函数统一成一致。

IDatabase.php

<?php
namespace Baobab;

interface IDatabase{
    function connect($host, $user, $passwd, $dbname);
    function query($sql);
    function fetch_result($result);
    function close();
}

Mysqli.php

<?php
namespace Baobab\Database;

use Baobab\IDatabase;
class Mysqli implements IDatabase{
    protected $conn;
    function connect($host, $user, $passwd, $dbname){
        $conn = mysqli_connect($host, $user, $passwd, $dbname);
        mysqli_set_charset($conn, 'utf8');
        $this->conn = $conn;
    }

    function query($sql) {
        return mysqli_query($this->conn, $sql);
    }

    function fetch_result($result){
        return mysqli_fetch_all($result);
    }

    function close() {
        mysqli_close($this->conn);
    }
}

Pdo.php

<?php
namespace Baobab\Database;

use Baobab\IDatabase;
class Pdo implements IDatabase{
    protected $conn;
    function connect($host, $user, $passwd, $dbname){
       $conn =  new \PDO("mysql:dbname=$dbname;host=$host", $user, $passwd);
       $this->conn = $conn;
    }

    function query($sql){
        return $this->conn->query($sql);
    }

    function fetch_result($result){

    }

    function close() {
        unset($this->conn);
    }
}

index.php

$db = new Baobab\Database\Mysqli();
$db->connect('127.0.0.1', 'root', '', 'test');
$res = $db->query('select * from ha_cl');
print_r($db->fetch_result($res));
$db->close();

还可以参考  http://www.phppan.com/2010/07/php-design-pattern-10-adapter/