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);

}