实例
<?php
/**
* 模拟tp5中的数据查询链式操作
* Db::table()->fields()->where()->select();
*/
require ('Query.php');
class Db{
public static function __callStatic($name, $arguments)
{
return call_user_func_array([(new Query()),$name],$arguments);
}
}
$res = Db::table('stuclass')
->fields('id,name,age')
->where('classid=1')
->select();
$table = '<table cellspacing="0" cellpadding="0" border="1" width="300"><tr><th>ID</th><th>姓名</th><th>地址</th></tr>';
$table .= '<caption>学生班级表</caption>';
foreach ($res as $value)
{
$table .= "<tr align='center'><td>{$value['id']}</td><td>{$value['name']}</td><td>{$value['age']}</td></tr>";
}
$table .='</table>';
echo $table;
/***********下面是query.php 文件*******************/
class Query{
//$sql
private $sql=[];
private $pdo;
function __construct()
{
$this->pdo = new PDO('mysql:host=127.0.0.1;dbname=stu','root','root');
}
public function table($table)
{
$this->sql['table'] = $table;
return $this;
}
public function fields($fields)
{
$this->sql['fields'] = $fields;
return $this;
}
public function where($where)
{
$this->sql['where'] = $where;
return $this;
}
public function select()
{
$sql = "select {$this->sql['fields']} from {$this->sql['table']} where {$this->sql['where']}";
$stmt = $this->pdo->prepare($sql);
$stmt ->execute();
$row = $stmt->fetchAll(PDO::FETCH_ASSOC);
return $row;
}
}运行实例 »
点击 "运行实例" 按钮查看在线实例
后期静态绑定的原理与使用场景分析:
代码的执行分两个阶段：编译阶段、运行阶段;
在运行阶段才确定方法的调用者的技术叫静态绑定;
后期静态绑定:静态继承的上下文环境,用于动态设置静态方法的调用者
