php学习笔记之面向对象编程_php技巧

一个php初学者的一个学习笔记的面向对象编程实例，有需要学习的朋友可参考下，脚本之家也更新了很多大家可以查阅下

<?php
class db { 
    private $mysqli; //数据库连接 
    private $options; //SQL选项 
    private $tableName; //表名 
    public function __construct($tabName) { 
        $this->tableName = $tabName; 
        $this->db (); 
    } 
    private function db() { 
        $this->mysqli = new mysqli ( &#39;localhost&#39;, &#39;root&#39;, &#39;&#39;, &#39;hdcms&#39; ); 
        $this->mysqli->query("SET NAMES GBK"); 
    } 
    public function fields($fildsArr) { 
        if (empty ( $fildsArr )) { 
            $this->options [&#39;fields&#39;] = &#39;&#39;; 
        } 
        if (is_array ( $fildsArr )) { 
            $this->options [&#39;fields&#39;] = implode ( &#39;,&#39;, $fildsArr ); 
        } else { 
            $this->options [&#39;fields&#39;] = $fildsArr; 
        } 
        return $this; 
    } 
    public function order($str) { 
        $this->options [&#39;order&#39;] = "ORDER BY " . $str; 
        return $this; 
    } 
    public function select() { 
        $sql = "SELECT {$this->options[&#39;fields&#39;]} FROM {$this->tableName}  {$this->options[&#39;order&#39;]}"; 
        return $this->query ( $sql ); 
    } 
    private function query($sql) { 
        $result = $this->mysqli 
            ->query ( $sql ); 
        $rows = array (); 
        while ( $row = $result->fetch_assoc () ) { 
            $rows [] = $row; 
        } 
        return $rows; 
    } 
    private function close() { 
        $this->mysqli 
            ->close (); 
    } 
    function __destruct() { 
        $this->close (); 
    } 
} 
$chanel = new db ( "hdw_channel" ); 
$chanelInfo = $chanel->fields ( &#39;id,cname,cpath&#39; ) 
    ->select (); 
echo "<pre class="brush:php;toolbar:false">"; 
print_r ( $chanelInfo );

class a { 
    protected  function aa(){ 
        echo 222; 
    } 
} 
class b extends a{ 
    function bb(){ 
        $this->aa(); 
    } 
} 
$c = new b(); 
$c->bb();

public   公有的：本类，子类，外部对象都可以调用
protected 受保护的：本类 子类，可以执行，外部对象不可以调用
private 私有的：只能本类执行，子类与外部对象都不可调用