<?php
header('content-type:text/html;charset=utf-8');
/*
掌握满足单例模式的必要条件
(1)私有的构造方法-为了防止在类外使用new关键字实例化对象
(2)私有的成员属性-为了防止在类外引入这个存放对象的属性
(3)私有的克隆方法-为了防止在类外通过clone成生另一个对象
(4)公有的静态方法-为了让用户进行实例化对象的操作
*/
class ConnectMysqli{
  //私有的属性
  private static $dbcon=false;
  private $host;
  private $port;
  private $user;
  private $pass;
  private $db;
  private $charset;
  private $link;
  //私有的构造方法
  private function __construct($config=array()){
    $this->host = $config['host'] ? $config['host'] : 'localhost';
    $this->port = $config['port'] ? $config['port'] : '3306';
    $this->user = $config['user'] ? $config['user'] : 'root';
    $this->pass = $config['pass'] ? $config['pass'] : 'root';
    $this->db = $config['db'] ? $config['db'] : 'small2';
    $this->charset=isset($arr['charset']) ? $arr['charset'] : 'utf8';
    //连接数据库
    $this->db_connect();
    //选择数据库
    $this->db_usedb();
    //设置字符集
    $this->db_charset();
   }
   //连接数据库
   private function db_connect(){
    $this->link=mysqli_connect($this->host.':'.$this->port,$this->user,$this->pass);
    if(!$this->link){
      echo "数据库连接失败<br>";
      echo "错误编码".mysqli_errno($this->link)."<br>";
      echo "错误信息".mysqli_error($this->link)."<br>";
      exit;
    }
   }
   //设置字符集
    private function db_charset(){
     mysqli_query($this->link,"set names {$this->charset}");
    }
    //选择数据库
   private function db_usedb(){
     mysqli_query($this->link,"use {$this->db}");
   }
   //私有的克隆
   private function __clone(){
     die('clone is not allowed');
   }
   //公用的静态方法
   public static function getIntance(){
     if(self::$dbcon==false){
      self::$dbcon=new self;
     }
     return self::$dbcon;
   }
   //执行sql语句的方法
    public function query($sql){
     $res=mysqli_query($this->link,$sql);
     if(!$res){
      echo "sql语句执行失败<br>";
      echo "错误编码是".mysqli_errno($this->link)."<br>";
      echo "错误信息是".mysqli_error($this->link)."<br>";
     }
     return $res;
   }
   //打印数据
    public function p($arr){
      echo "<pre>";
      print_r($arr);
      echo "</pre>";
    }
    public function v($arr){
    echo "<pre>";
      var_dump($arr);
      echo "</pre>";
    }
    //获得最后一条记录id
    public function getInsertid(){
     return mysqli_insert_id($this->link);
    }
   /**
    * 查询某个字段
    * @param
    * @return string or int
    */
    public function getOne($sql){
     $query=$this->query($sql);
      return mysqli_free_result($query);
    }
    //获取一行记录,return array 一维数组
    public function getRow($sql,$type="assoc"){
     $query=$this->query($sql);
     if(!in_array($type,array("assoc",'array',"row"))){
       die("mysqli_query error");
     }
     $funcname="mysqli_fetch_".$type;
     return $funcname($query);
    }
    //获取一条记录,前置条件通过资源获取一条记录
    public function getFormSource($query,$type="assoc"){
    if(!in_array($type,array("assoc","array","row")))
    {
      die("mysqli_query error");
    }
    $funcname="mysqli_fetch_".$type;
    return $funcname($query);
    }
    //获取多条数据，二维数组
    public function getAll($sql){
     $query=$this->query($sql);
     $list=array();
     while ($r=$this->getFormSource($query)) {
      $list[]=$r;
     }
     return $list;
    }
     /**
     * 定义添加数据的方法
     * @param string $table 表名
     * @param string orarray $data [数据]
     * @return int 最新添加的id
     */
     public function insert($table,$data){
     //遍历数组，得到每一个字段和字段的值
     $key_str='';
     $v_str='';
     foreach($data as $key=>$v){
      if(empty($v)){
       die("error");
     }
        //$key的值是每一个字段s一个字段所对应的值
        $key_str.=$key.',';
        $v_str.="'$v',";
     }
     $key_str=trim($key_str,',');
     $v_str=trim($v_str,',');
     //判断数据是否为空
     $sql="insert into $table ($key_str) values ($v_str)";
     $this->query($sql);
    //返回上一次增加操做产生ID值
     return $this->getInsertid();
   }
   /*
    * 删除一条数据方法
    * @param1 $table, $where=array('id'=>'1') 表名 条件
    * @return 受影响的行数
    */
    public function deleteOne($table, $where){
      if(is_array($where)){
        foreach ($where as $key => $val) {
          $condition = $key.'='.$val;
        }
      } else {
        $condition = $where;
      }
      $sql = "delete from $table where $condition";
      $this->query($sql);
      //返回受影响的行数
      return mysqli_affected_rows($this->link);
    }
    /*
    * 删除多条数据方法
    * @param1 $table, $where 表名 条件
    * @return 受影响的行数
    */
    public function deleteAll($table, $where){
      if(is_array($where)){
        foreach ($where as $key => $val) {
          if(is_array($val)){
            $condition = $key.' in ('.implode(',', $val) .')';
          } else {
            $condition = $key. '=' .$val;
          }
        }
      } else {
        $condition = $where;
      }
      $sql = "delete from $table where $condition";
      $this->query($sql);
      //返回受影响的行数
      return mysqli_affected_rows($this->link);
    }
   /**
    * [修改操作description]
    * @param [type] $table [表名]
    * @param [type] $data [数据]
    * @param [type] $where [条件]
    * @return [type]
    */
   public function update($table,$data,$where){
     //遍历数组，得到每一个字段和字段的值
     $str='';
    foreach($data as $key=>$v){
     $str.="$key='$v',";
    }
    $str=rtrim($str,',');
    //修改SQL语句
    $sql="update $table set $str where $where";
    $this->query($sql);
    //返回受影响的行数
    return mysqli_affected_rows($this->link);
   }
}
?>
用法测试：    
//mysqli测试
$db=ConnectMysqli::getIntance();
//var_dump($db);
/*$sql="select * from acticle";
$list=$db->getAll($sql);
$db->p($list);*/
/*$sql="select * from acticle where acticle_id=95";
$list=$db->getRow($sql);
$db->p($list);
*/
/*$sql="select title from acticle";
$list=$db->getOne($sql);
$db->p($list);不行*/
//$list=$db->insert("users",$_POST);
//$del=$db->deleteOne("users","id=29");
//$del=$db->deleteAll("users","id in(27,28)");
//$up=$db->update("users",$_POST,"id=27");
//print_R($list);