菜鸟mysqli问题

Question

菜鸟求问现在要把数据库包装下函数但是每个函数里都要声明全局变量才行global$mysqli;该怎么写法才好function_connect(){//MYSQL服务器连接global$mysqli;$mysqli=@newmysqli('localhost','root','root','ken123');if($mysqli->connect_error){die('ConnectError:'.$mysqli->connect_error);}if(!$mysqli->set_charset("utf8")){exit('字符集不存在！');};}function_query($_sql){//执行SQL语句global$mysqli;if(!$result=$mysqli->query($_sql)){exit('SQL执行失败！');};return$result;}

Answer 1

phpclassmysqli{
private$mysqli;
function__construct(){
$this->mysqli=@newmysqli('localhost','root','root','ken123');
if($this->mysqli->connect_error){
die('ConnectError:'.$this->mysqli->connect_error);
}
if(!$this->mysqli->set_charset("utf8")){
exit('字符集不存在！');
};
}
function_query($_sql){//执行SQL语句
if(!$result=$this->mysqli->query($_sql)){
exit('SQL执行失败！');
};
return$result;
}
}
                            

Answer 2

$mysqli=newmysqli();
functioncrud(){global$mysqli;}
register_shutdown_function(function(){
global$mysqli;
$mysqli->close();
});
很多人都觉得全局变量没有OOP的依赖注入那么优雅,但优雅能当饭吃吗?
为了优雅,是不是连PHP提供的超全局变量也不用了?简单直观才是PHP的王道.
依赖注入是一种解耦组件之间依赖关系的设计模式,可以用来替代全局变量.
classFactory{
publicstaticfunctiongetDb(){
include"./Lib/Db.php";
returnnewDb("localhost","root","123456","test");
}
}
classexample{
private$_db;
functiongetList(){
$this->_db->query("...");
}
functionsetDb($connection){
$this->_db=$connection;
}
}
$example=newexample();//example类依赖数据库
$example->setDb(Factory::getDb());//从外部注入数据库连接(依赖注入)
$example->getList();//访问数据库,读取数据