模仿DISCUZ的单列模式链接mysql

dly · 发表于 2012-11-8 19:44:37

单列模式：顾名思义就是只new一次，其实每次new一个类的时候内存都会新建一个空地存放那些属性和方法，所以单列模式就很好的防止类重复的被实例化，浪费内存资源。
我这里看着discuzX2的class_core.php文件慢慢琢磨的。请高手指教。

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class DB {
static $link ;
static $config ;
function DB(){
return true;
}
function &instance() {//单列模式
static $object;
if(empty($object)) {
$object = new DB();
}
return $object;
}
function connect($config){
$config['dbconnect'] = mysql_connect($config['db']['server'],$config['db']['user'],$config['db']['passwd']) or die("mysql link error");
mysql_selectdb($config['db']['table']);
mysql_set_charset($config['db']['charset']);
return $config;
}
function query($sql){
$query = mysql_query($sql);
return $query;
}
function insert_id(){
return mysql_insert_id();
}
function insert($arr,$table=''){
$arr = is_array($arr) ? $arr : array($arr);
if($table='') return false;
$sql = "INSERT INTO {$table} VALUES(";
foreach($arr as $key=>$value){
$sql .= " $value ,";
}
return $this->query(substr($sql, 0,-1).')') or die('mysql_insert_error');
}
function update($arr,$table,$where=''){
$arr = is_array($arr) ? $arr : array($arr);
if($table='') return false;
$sql = "UPDATE {$table} SET";
foreach($arr as $key=>$value){
$sql .= "{$key} = {$value} ,";
}
if($where!=''){
$where = " WHERE {$where}";
$sql = substr($sql, 0,-1).')' . $where;
}else{
$sql =substr($sql, 0,-1).')';
}
return $this->query($sql) or die('mysql_insert_error');
}
function delete($table,$where=''){
if($where!=''){
$where = " WHERE {$where}";
}
$sql = "DELETE FROM `$table` $where";
return $this->query($sql) or die('mysql_insert_error');
}
function table($str){
return $str = DB::$config['db']['pre'] . $str;
}
}

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[二次开发] 模仿DISCUZ的单列模式链接mysql