工厂模式：单例模式封装数据库的具体操作（PDO）

php  封装mysql的类

interface等 需自己定义  单例模式不适用于工厂模式，若是需要 引入到工厂模式

<?php
header('content-type:text/html;charset=utf-8');

require 'MysqlPdoDB.class.php';
require 'MysqliDB.class.php';
require './DB.config.php';
class DBFactory{
    public function createPdo(){
        return MysqlDB::getInstance();
    }
    public function create2(){
        #code
    }
    //..如此（单例模式） 不能传参数进行 分类的引用类
}

  具体的类代码

<?php
header('content-type:text/html;charset=utf-8');
require './DB.config.php';
require './DB.interface.php';
class mysqlDB {

    private static $obj;//私有的静态变量 储存 实例化的类
    public $table;
    public $dsn;
    public $pdo;

    private function __clone(){
        trigger_error('Clone is not allow',E_USER_ERROR);//若是克隆 报错提醒 这是不被允许的
    }//私有的克隆方法

    private final function __construct()//私有的不可被继承的 构造方法
    {
        $cfg=require './DB.config.php';
        $dsn['dsn']=$cfg['dsn'];
        $dsn['username']=$cfg['username'];
        $dsn['password']=$cfg['password'];
        $dsn['charset']=$cfg['charset'];
        $this->dsn=$dsn;
        $pdo=new PDO($this->dsn['dsn'],$this->dsn['username'],$this->dsn['password']);
        $pdo->exec("set names ".$this->dsn['charset']."");
        $this->pdo=$pdo;
        return $this;
    }
    public function getInstance()
    {
        if(!self::$obj instanceof self){//instanceof 用于确定一个 PHP 变量是否属于某一类 class 的实例：
            self::$obj=new self;
        }
        return self::$obj;
    }
    public function connect(){

    }
    public function table($tableName){
        $tableName=trim($tableName);
        $this->table=$tableName;
        return $this;
    }
    public function insert($data){//进行添加  返回 上一条的添加值
        $keyStr="";
        $valStr="";
        foreach($data as $k=>$v){
            $keyStr.=','.$k;
            $valStr.=','."'$v'";
        }
        $keyStr=trim($keyStr,',');
        $valStr=trim($valStr,',');

        $sql="INSERT INTO ".$this->table." ($keyStr) VALUES($valStr)";
        $res=$this->pdo->exec($sql);
        if($res){
            return $this->pdo->lastInsertId();
        }else{
            return $this->pdo->errorInfo();
        }

    }
    public function select($columns, $join = null, $where = null, $group = null, $having = null, $order = null, $limit = null){
        $columns = implode(',', array_values($columns));
        // 需要加条件判断是否为空，是否需要拼接
        $sql = "select ".$columns." from `".$this->table."` ";
        if($join!=null){
            $sql .= $join;
        }
        if($where!=null){
            $sql .= " where ".$where;
        }
        if($group!=null){
            $sql .= " group by ".$group;
        }
        if($having!=null){
            $sql .= " having ".$having;
        }
        if($order!=null){
            $sql .= " order by ".$order;
        }
        if($limit!=null){
            $sql .= " limit ".$limit;
        }

        //echo $sql;exit;
        $res = $this->pdo->query($sql);
        return $res;
    }
    public  function getRow($field='*',$where)
    {//获取 单行数据    参数为  字段名和where条件  （数据类型为数组）
        $whereStr=1;
        if(!empty($where)){
            foreach ($where as $k => $val) {
                $whereStr.=" AND ".$k."="."'$val'";
            }
        }
        $whereStr=substr($whereStr,5);
        //$fieldStr='*';
        if(!empty($field)){
            $field=trim($field,',');
        }

        $sql= "select $field from ".$this->table." where $whereStr";
        $data=$this->pdo->query($sql)->fetch(PDO::FETCH_ASSOC);
        return $data;

    }
    public function getOne($field="*",$where)
    {//获取 单个字段名的数据  参数为字段名（string） 和where条件（array）
        $whereStr=1;
        if(!empty($where)){
            foreach ($where as $k => $val) {
                $whereStr.=" AND ".$k."="."'$val'";
            }
        }
        $whereStr=substr($whereStr,5);

        if(!empty($field)){
            $field=trim($field,',');
        }

        $sql= "select $field from ".$this->table." where $whereStr";
        $data=$this->pdo->query($sql)->fetchAll(PDO::FETCH_ASSOC);
        return $data;

    }
    public function getAll()//所有数据
    {
        $sql="select * from ".$this->table ;
        $res=$this->pdo->query($sql)->fetchAll(PDO::FETCH_ASSOC);
        return $res;
    }
    public function update($data,$where)//改
    {
        $setStr="";
        foreach($data as $k=>$v){
            $setStr.=$k.'='."'$v'".',';
        }
        $whereStr="";
        foreach ($where as $k => $val) {
            $whereStr.=" AND ".$k."="."'$val'";
        }
        $whereStr=substr($whereStr,5);
        $setStr=trim($setStr,',');
        $sql="update ".$this->table." set  $setStr where $whereStr";
        $res=$this->pdo->exec($sql);
        return  $res;
    }
    public function delete($where)//删除
    {   $str="";
        foreach ($where as $k => $val) {
            $str.=" AND ".$k."="."'$val'";
        }
        $str=substr($str,5);
        $sql="delete from $this->table where $str";
        $res=$this->pdo->exec($sql);
        return $res;
    }
}
$mysql=mysqlDB::getInstance();

$data=array(
    'title'=>'测试数据',
    'contents'=>'测试数据内容'
);

$res=$mysql->table('news')->insert($data);
var_dump($res);

给一个接口 具体方法 可以加入接口中 并使用

implements  引用
interface DB{
    //增加 arr为传入的数组
    public function insert($arr);
    //查询
    public function select();
    //修改
    public function update($arr,$where);
    //删除
    public function delete($where);
    //执行sql语句
    public function query($sql);
    public function table($tableName);

}