通过静态方法传入不同的参数创建不同的对象，实现对象创建和使用的分离
<?php
class mysql_conn {
private $dbh = null;
private $host = 'localhost';
private $port = '3306';
private $user = 'root';
private $password = '****';
private $dbname = 'test';
public function __construct() {
$this->dbh = new PDO('mysql:host=' . $this->host . ';port=' . $this->port . ';dbname=' . $this->dbname, $this->user, $this->password);
}
public function get_table_data($table_name) {
foreach($this->dbh->query("SELECT * from `$table_name`") as $row) {
echo "<pre>";
print_r($row);
echo "</pre>";
}
}
}
class psql_conn {
private $dbh = null;
private $host = 'localhost';
private $port = '5432';
private $user = 'postgres';
private $password = '****';
private $dbname = 'test';
public function __construct() {
$this->dbh = new PDO('pgsql:host=' . $this->host . ';port=' . $this->port . ';dbname=' . $this->dbname, $this->user, $this->password);
}
public function get_table_data($table_name) {
foreach($this->dbh->query("SELECT * from `$table_name`") as $row) {
echo "<pre>";
print_r($row);
echo "</pre>";
}
}
public function custom_query($sql) {
$stmt = $this->dbh->prepare($sql);
$stmt->execute();
foreach ($stmt as $row) {
echo "<pre>";
print_r($row);
echo "</pre>";
}
}
}
class Factory {
public static function pdo_conn($db = 'mysql') {
if ($db == 'mysql') {
return new mysql_conn();
}
else if ($db == 'psql') {
return new psql_conn();
}
}
}
// mysql
// $mysql_dbh = Factory::pdo_conn('mysql');
// $mysql_dbh->get_table_data('user');
// $mysql_dbh->get_table_data('order');
// postgresql
// $psql_dbh = Factory::pdo_conn('psql');
// $psql_dbh->custom_query('select * from student');通过上面的代码可以看出，简单工厂的缺点就是后面如果想增加新的连接，需要频繁地去修改静态方法
通过定义一个抽象的核心工厂类，并定义创建产品对象的接口。
创建具体产品示例的工作延迟到其工厂子类去完成。
当系统需要新增一个产品是，无需修改现有系统代码，只需要添加一个具体产品类和其对应的工厂子类，使系统的扩展性变得很好，符合面向对象编程的开闭原则;
<?php
interface database_option {
public function custom_query($sql);
public function get_table_data($table_name);
}
class mysql_conn implements database_option {
private $dbh = null;
private $host = 'localhost';
private $port = '3306';
private $user = 'root';
private $password = '****';
private $dbname = 'test';
public function __construct() {
$this->dbh = new PDO('mysql:host=' . $this->host . ';port=' . $this->port . ';dbname=' . $this->dbname, $this->user, $this->password);
}
public function get_table_data($table_name) {
foreach($this->dbh->query("SELECT * from `$table_name`") as $row) {
echo "<pre>";
print_r($row);
echo "</pre>";
}
}
public function custom_query($sql) {
$stmt = $this->dbh->prepare($sql);
$stmt->execute();
foreach ($stmt as $row) {
echo "<pre>";
print_r($row);
echo "</pre>";
}
}
}
class psql_conn implements database_option {
private $dbh = null;
private $host = 'localhost';
private $port = '5432';
private $user = 'postgres';
private $password = '****';
private $dbname = 'test';
public function __construct() {
$this->dbh = new PDO('pgsql:host=' . $this->host . ';port=' . $this->port . ';dbname=' . $this->dbname, $this->user, $this->password);
}
public function get_table_data($table_name) {
foreach($this->dbh->query("SELECT * from `$table_name`") as $row) {
echo "<pre>";
print_r($row);
echo "</pre>";
}
}
public function custom_query($sql) {
$stmt = $this->dbh->prepare($sql);
$stmt->execute();
foreach ($stmt as $row) {
echo "<pre>";
print_r($row);
echo "</pre>";
}
}
}
abstract class Factory {
abstract static function pdo_conn();
}
class mysql_Factory extends Factory {
public static function pdo_conn() {
return new mysql_conn();
}
}
class psql_Factory extends Factory {
public static function pdo_conn() {
return new psql_conn();
}
}
// mysql
// $mysql_dbh = mysql_Factory::pdo_conn();
// $mysql_dbh->get_table_data('order');
// psql
// $psql_dbh = psql_Factory::pdo_conn();
// $psql_dbh->custom_query('select * from student');工厂方法是简单工厂的进一步抽象，由于使用了面向对象的多态性，工厂方法保持了简单工厂的优点，在工厂方法中，核心的工厂类不再负责所有产品的创建，而是将具体创建工作交给子类。所以可以在不修改工厂方法的情况下引入新的产品，复合开闭原则。
提供一个创建一系列相关或相互依赖对象的接口，而无须指定它们具体的类。
在工厂方法模式中，一个具体的工厂负责生产一类具体的产品，即一对一的关系，但是，如果需要一个具体的工厂生产多种产品对象，那么就需要用到抽象工厂模式了。
<?php
interface database_option {
public function custom_query($sql);
public function get_table_data($table_name);
}
class mysql_conn implements database_option {
private $dbh = null;
private $host = 'localhost';
private $port = '3306';
private $user = 'root';
private $password = '****';
private $dbname = 'test';
public function __construct() {
$this->dbh = new PDO('mysql:host=' . $this->host . ';port=' . $this->port . ';dbname=' . $this->dbname, $this->user, $this->password);
}
public function get_table_data($table_name) {
foreach($this->dbh->query("SELECT * from `$table_name`") as $row) {
echo "<pre>";
print_r($row);
echo "</pre>";
}
}
public function custom_query($sql) {
$stmt = $this->dbh->prepare($sql);
$stmt->execute();
foreach ($stmt as $row) {
echo "<pre>";
print_r($row);
echo "</pre>";
}
}
}
class psql_conn implements database_option {
private $dbh = null;
private $host = 'localhost';
private $port = '5432';
private $user = 'postgres';
private $password = '****';
private $dbname = 'test';
public function __construct() {
$this->dbh = new PDO('pgsql:host=' . $this->host . ';port=' . $this->port . ';dbname=' . $this->dbname, $this->user, $this->password);
}
public function get_table_data($table_name) {
foreach($this->dbh->query("SELECT * from `$table_name`") as $row) {
echo "<pre>";
print_r($row);
echo "</pre>";
}
}
public function custom_query($sql) {
$stmt = $this->dbh->prepare($sql);
$stmt->execute();
foreach ($stmt as $row) {
echo "<pre>";
print_r($row);
echo "</pre>";
}
}
}
abstract class Factory {
abstract public static function create_mysql_conn();
abstract public static function create_psql_conn();
}
class db_Factory extends Factory {
public static function create_mysql_conn() {
return new mysql_conn();
}
public static function create_psql_conn() {
return new psql_conn();
}
}
// mysql
// $mysql_dbh = db_Factory::create_mysql_conn();
// $mysql_dbh->get_table_data('order');
// psql
// $psql_dbh = db_Factory::create_psql_conn();
// $psql_dbh->custom_query('select * from student');原文地址：https://www.ryanzoe.top/%e8%ae%be%e8%ae%a1%e6%a8%a1%e5%bc%8f/php-factory-design-pattern/
