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/