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php模式-数据映射模式

概念：简言之，数据映射模式就是将对象和数据存储映射起来，对一个对象的操作会映射为对数据存储的操作。

深入理解：数据映射，是在持久化数据存储层（一般是关系型数据库）和驻于内存的数据表现层之间进行双向数据传输的数据访问层。

数据映射模式的目的是让持久化数据存储层，驻于内存的数据表现层，以及数据映射本身三者相互独立、互不依赖。这个数据访问层由一个映射器（或者数据访问对象）组成，用于实现数据传输。通用的数据访问层可以处理不同的实体类型，而专用的则处理一个或几个。

数据映射模式的核心在于它的数据模型遵循单一职责原则（single Responsibility Principle）,这也是和Active Record模式的不同之处。最典型的数据映射模式例子就是数据库ORM模型（Object Relational Mapper）。

代码演示：

1.表结构

+---------+------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+---------+------------------+------+-----+---------+----------------+
| id | int(11) unsigned | NO | PRI | NULL | auto_increment |
| name | varchar(32) | NO | | | |
| mobile | int(11) | NO | | 0 | |
| regtime | timestamp | YES | | NULL | |
+---------+------------------+------+-----+---------+----------------+

2.代码结构

LibsIDatabase.php

<?php
namespace Libs;

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

LibsDatabaseMySQLi.php

<?php
namespace LibsDatabase;

use LibsIDatabase;
class MySQLi implements IDatabase
{
    protected $conn;
    
    public function connect($host,$user,$pwd,$dbname)
    {
        $conn = mysqli_connect($host,$user,$pwd,$dbname);
        $this->conn = $conn;
    }
    public function query($sql)
    {
        $res = mysqli_query($this->conn,$sql);
        return $res;
    }
    public function close()
    {
        mysqli_close($this->conn);
    }

}

LibsFactory.php

<?php
namespace Libs;

class Factory
{
    public static function getUser($id)
    {
        $key = 'user_'.$id;
        $user = Register::get($key);
        if(!$user){
            $user = new User($id);
            Register::set($key, $user);
        }
        
        return $user;
    }
}

LibsUser.php

<?php
namespace Libs;

class User
{
    public $id;
    public $name;
    public $mobile;
    public $regtime;
    
    protected $db;
    public function __construct($id)
    {
        $this->db = new LibsDatabaseMySQLi();
        $this->db->connect(DBHOST, DBUSER, DBPWD, DBNAME);
        $res = $this->db->query("SELECT * FROM user WHERE id={$id} LIMIT 1");
        
        $data = $res->fetch_assoc();
        $this->id= $id;
        $this->mobile = $data['mobile'];
        $this->name = $data['name'];
        $this->regtime = $data['regtime'];
        
    }
    public function __destruct()
    {
        $this->db->query("update user set name='{$this->name}',mobile='{$this->mobile}',regtime='{$this->regtime}' where id={$this->id} limit 1");
        
    }
}

LibsUserMapper.php

<?php
namespace Libs;

class UserMapper
{
    public  function index($id)
    {
        $user = LibsFactory::getUser($id);
        $user->mobile = "1891111111";
        $this->changeName($id);
        echo "done";        
    }
    public function changeName($id)
    {
        $user = LibsFactory::getUser($id);
        $user->name = "sacha";
    }
}

调用

 

define("DBHOST",'127.0.0.1');
define("DBUSER",'user');
define("DBPWD",'pwd');
define("DBNAME",'test');

$um = new LibsUserMapper();
$um->index(1);