class
Mysql{
public
static
$conn
;
public
static
function
getInstance(){
if
(!self::
$conn
){
new
self();
return
self::
$conn
;
}
else
{
return
self::
$conn
;
}
}
private
function
__construct(){
self::
$conn
= "mysql_connect:";
// mysql_connect('','','')
}
public
function
__clone()
{
trigger_error("Only one connection");
}
}
echo
Mysql::getInstance();
echo
Mysql::getInstance();
实际中用作数据库连接类和工厂模式一起使用,根据参数调用单例模式,可以提高资源使
用效率。