PHP连接mysql数据库之根据配置文件选择mysqli还是pdo方式

配置文件config.php

<?php
return array(
'DB' => array(
'default_extension' => 'mysqli',
),
);

接口I_DB.interface.php

<?php
interface I_DB{
public static function getInstance($config);
public function my_query($sql);
public function fetchAll($sql);
public function fetchRow($sql);
public function fetchColumn($sql);
}

Mysqli连接配置文件MysqliDB.class.php

<?php
header("content-type:text/html;charset=utf-8");
include "./I_DB.interface.php";
class MysqliDB implements I_DB{
//私有的属性
private static $instance; //用来保存单例对象
private $host;         //主机名称
private $port;         //主机端口号
private $user;         //数据库用户名
private $pass;         //数据库密码
private $dbname;           //要操作的数据库名称
private $charset;      //要设置的字符集
private $link;         //数据库连接句柄
/**
* 私有的构造方法
* 初始化参数
* 数据库连接三步曲
* 1、连接数据库
* 2、选择数据库
* 3、设置字符集
*/
private function __construct($config){
//初始化属性的值
$this->init($config);
//连接数据库
$this->db_connect();
//选择数据库
$this->db_usedb();
//设置字符集
$this->db_charset();
}
//接收配置参数
private function init($config){
$this->host = isset($config['host']) ? $config['host']:'localhost';
$this->port = isset($config['port']) ? $config['port'] : '3306';
$this->user = isset($config['user']) ? $config['user'] : 'root';
$this->pass = isset($config['pass']) ? $config['pass'] : '';
$this->dbname = isset($config['dbname']) ? $config['dbname'] : '';
$this->charset=isset($config['charset']) ? $config['charset'] : 'utf8';
}
//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！
";
echo "错误编码：".mysqli_errno($this->link)."
";
echo "错误信息：".mysqli_error($this->link)."
";
exit;
}
}
/**
* 数据查询并对错误进行处理
* @param string $sql
* @return mixed(book|resource)
*/
public function my_query($sql){
$res = mysqli_query($this->link,$sql);
if(!$res){
echo "sql语句执行失败
";
echo "错误编码是".mysqli_errno($this->link)."
";
echo "错误信息是".mysqli_error($this->link)."
";
}
return $res;
}

/**
* 返回多选多列的结果集，二维数组
* @param  string $sql 一条sql语句
* @return mixed(array|false) 执行成功是数组，失败是false
*/
public function fetchAll($sql){
//执行sql
if($res = $this->my_query($sql)){
$rows = [];
while($row = mysqli_fetch_assoc($res)){
$rows[] = $row;
};
//结果集使用完毕，主动释放
mysqli_free_result($res);
return $rows;
}else{
return false;
}
}
//返回一条记录
public function fetchRow($sql){
//先执行
if($res = $this->my_query($sql)){
$row = mysqli_fetch_assoc($res);
mysqli_free_result($res);
return $row;
}else{
return false;
}
}
//返回单一值，也就是单行单列
public function fetchColumn($sql){
//先执行
if($res = $this->my_query($sql)){
$row = mysqli_fetch_row($res);
mysqli_free_result($res);
return isset($row[0])?$row[0]:false
;
}else{
return false;
}

}
//设置字符集
private function db_charset(){
$sql = "set names $this->charset";
return $this->my_query($sql);
}
//选择数据库
private function db_usedb(){
$sql = "use $this->dbname";
return $this->my_query($sql);
}
//私有的克隆,不允许克隆创建对象
private function __clone(){
die('clone is not allowed');
}
//公开的静态方法
public static function getInstance($config){
if(!self::$instance instanceof self){
self::$instance = new self($config);
}
return self::$instance;
}

public function __destruct(){
@mysqli_close($this->link);
}
}

PDO连接配置文件PDODB.class.php

<?php
header('content-type:text/html;charset=utf-8');
include './I_DB.interface.php';
class PDODB implements I_DB{
//私有的属性
private static $instance; //用来保存单例对象
private $host;         //主机名称
private $port;         //主机端口号
private $user;         //数据库用户名
private $pass;         //数据库密码
private $dbname;           //要操作的数据库名称
private $charset;      //要设置的字符集
private $dsn;         //数据资源名称
private $pdo;         // pdo连接
/**
* 私有的构造方法
* 初始化参数
* 数据库连接三步曲
* 1、连接数据库
* 2、选择数据库
* 3、设置字符集
*/
private function __construct($config){
//初始化属性
$this->initParams($config);
//初始化dsn
$this->initDSN();
//初始化pdo
$this->initPDO();
//初始化PDO对象的属性
$this->initAttribute();
}
// 对外公开的入口
public static function getInstance($config){
if(!self::$instance instanceof self){
self::$instance = new self($config);
}
return self::$instance;
}
// 初始化参数
private function initParams($config){
$this->host = isset($config['host']) ? $config['host']:'localhost';
$this->port = isset($config['port']) ? $config['port'] : '3306';
$this->user = isset($config['user']) ? $config['user'] : 'root';
$this->pass = isset($config['pass']) ? $config['pass'] : '';
$this->dbname = isset($config['dbname']) ? $config['dbname'] : '';
$this->charset=isset($config['charset']) ? $config['charset'] : 'utf8';
}
//初始化dsn
private function initDSN(){
$this->dsn = "mysql:host=$this->host;port=$this->port;dbname=$this->dbname;charset=$this->charset";
}
/**
* 输出异常信息
*/
private function my_error($e) {
echo 'SQL语句执行失败!<br />';
echo '错误的代码是:', $e->getCode(), '<br />';
echo '错误的信息是:', $e->getMessage(), '<br />';
echo '错误的脚本是:', $e->getFile(), '<br />';
echo '错误的行号是:', $e->getLine(), '<br />';
return false;
}
//初始化pdo
private function initPDO(){
try{
$this->pdo = new PDO($this->dsn,$this->user,$this->pass);
}catch(Exception $e){
$this->my_error($e);
}
}
// 初始化PDO对象的属性
private function initAttribute(){
$this->pdo->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_EXCEPTION);
}
// 查询语句
public function my_query($sql){
try{
$result = $this->pdo->exec($sql);
}catch(Exception $e){
$this->my_error($e);
}
return $result;
}
// 实现fetchAll抽象方法
public function fetchAll($sql){
try{
$stmt = $this->pdo->query($sql);
$result = $stmt->fetchAll(PDO::FETCH_ASSOC);
// 关闭游标，释放结果集
$stmt->closeCursor();
}catch(Exception $e){
$this->my_error($e);
}
return $result;
}
public function fetchRow($sql){
try{
$stmt = $this->$pdo->query($sql);
$result = $stmt->fetch(PDO::FETCH_ASSOC);
// 关闭游标，释放结果集
$stmt->closeCursor();
}catch(Exception $e){
$this->my_error($e);
}
return $result;
}
public function fetchColumn($sql){
try{
$stmt = $this->pdo->query($sql);
$result = $stmt->fetchColumn();
$stmt->closeCursor();
}catch(Exception $e){
$this->my_error($e);
}
return $result;
}
// 禁止克隆创建一个对象
private function __clone(){
die('clone is not allowed');
}
}

使用方法database.php

<?php
header("content-type:text/html;charset=utf-8");
$conf = include "./config.php";
$config = array(
"pass" => "789890",
"dbname" => "bbs"
);
switch ($conf['DB']['default_extension']) {
case 'mysqli':
include "./MysqliDB.class.php";
$db = MysqliDB::getInstance($config);
break;

case 'pdo' :
include "./PDODB.class.php";
$db = PDODB::getInstance($config);
}
$sql = "select * from user";
echo "<pre>";

var_dump($db->fetchAll($sql));