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php 实现dao模式

2026-02-16 20:47:25PHP

PHP 实现 DAO 模式

DAO（Data Access Object）模式是一种用于抽象和封装数据访问逻辑的设计模式，将底层数据操作与业务逻辑分离。以下是 PHP 中实现 DAO 模式的详细方法。

定义数据模型类

创建一个简单的数据模型类，表示业务实体。例如，用户模型：

class User {
    private $id;
    private $name;
    private $email;

    public function __construct($id, $name, $email) {
        $this->id = $id;
        $this->name = $name;
        $this->email = $email;
    }

    public function getId() { return $this->id; }
    public function getName() { return $this->name; }
    public function getEmail() { return $this->email; }
}

创建 DAO 接口

定义 DAO 接口，声明通用的数据访问方法：

interface UserDao {
    public function findById($id);
    public function findAll();
    public function save(User $user);
    public function update(User $user);
    public function delete($id);
}

实现具体 DAO 类

基于接口实现具体的 DAO 类，例如 MySQL 实现：

class UserDaoImpl implements UserDao {
    private $db;

    public function __construct(PDO $db) {
        $this->db = $db;
    }

    public function findById($id) {
        $stmt = $this->db->prepare("SELECT * FROM users WHERE id = :id");
        $stmt->execute([':id' => $id]);
        $row = $stmt->fetch(PDO::FETCH_ASSOC);
        return new User($row['id'], $row['name'], $row['email']);
    }

    public function findAll() {
        $stmt = $this->db->query("SELECT * FROM users");
        $users = [];
        while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
            $users[] = new User($row['id'], $row['name'], $row['email']);
        }
        return $users;
    }

    public function save(User $user) {
        $stmt = $this->db->prepare("INSERT INTO users (name, email) VALUES (:name, :email)");
        $stmt->execute([
            ':name' => $user->getName(),
            ':email' => $user->getEmail()
        ]);
        return $this->db->lastInsertId();
    }

    public function update(User $user) {
        $stmt = $this->db->prepare("UPDATE users SET name = :name, email = :email WHERE id = :id");
        $stmt->execute([
            ':id' => $user->getId(),
            ':name' => $user->getName(),
            ':email' => $user->getEmail()
        ]);
    }

    public function delete($id) {
        $stmt = $this->db->prepare("DELETE FROM users WHERE id = :id");
        $stmt->execute([':id' => $id]);
    }
}

使用工厂模式创建 DAO 实例

通过工厂类集中管理 DAO 实例的创建：

class DaoFactory {
    private static $db;

    public static function setDb(PDO $db) {
        self::$db = $db;
    }

    public static function getUserDao() {
        return new UserDaoImpl(self::$db);
    }
}

实际调用示例

在业务逻辑中使用 DAO：

php 实现dao模式

$db = new PDO('mysql:host=localhost;dbname=test', 'username', 'password');
DaoFactory::setDb($db);

$userDao = DaoFactory::getUserDao();

// 创建用户
$newUser = new User(null, 'John Doe', 'john@example.com');
$userId = $userDao->save($newUser);

// 查询用户
$user = $userDao->findById($userId);
echo $user->getName();

// 更新用户
$user->setName('Jane Doe');
$userDao->update($user);

// 删除用户
$userDao->delete($userId);