封装mysqli

<?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'] : 'wan';
        $this->charset=isset($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：

<?php
//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);