php _autoload自动加载类与机制分析

<?php
class abc{
function __construct()
{
echo 'www.111cn.net;
}
}
?>

function __autoload($classname){
$classpath=”./”.$classname.'.php';
if(file_exists($classpath)){
require_once($classpath);
}
else{
echo ‘class file'.$classpath.'not found!';
}
}

$newobj = new ClassA();
$newobj = new ClassB();

<form enctype="multipart/form-data" method="POST" target="upload" action="http://localhost/class.upload.php" >
          <input type="file" name="uploadfile" />
          <input type="submit" />
</form>
<iframe name="upload" style="display:none"></iframe>

class upload
{
   public $_file;

   public function __construct( $name =null)
   {
       if(is_null($name) || !isset($_FILES[$name]))
            $name = key($_FILES);
           
       if(!isset($_FILES[$name]))
           throw new Exception("并没有文件上传");
          
       $this->_file  = $_FILES[$name];
      
       if(!is_uploaded_file($this->_file['tmp_name']))
            throw new Exception("异常情况");
       if($this->_file['error'] !== 0)
            throw new Exception("错误代码:".$this->_file['error']);    
   }
   public function moveTo( $new_dir)
   {
       $real_dir = $this->checkDir($new_dir);
       return move_uploaded_file($this->_file['tmp_name'], $real_dir.'/'.$this->_file['name']);
   }
   private function checkDir($dir)
   {
       $real_dir = realpath($dir);
       if($real_dir === false)
           throw new Exception("给定目录{$dir}不存在");
       if(!is_writable($real_dir))
           throw new Exception("给定目录{$dir}不可写");
       return $real_dir;
   }

}

$inputName =  'uploadfile';
 // 即<input type=“file" name="uploadfile" /> 中的name值，不填也行
$upload = new upload($inputName);
$new_dir = "/www";  // 将文件移动到的路径
$upload->moveTo($new_dir);

$discuz = & discuz_core::instance();
[code language=php]

// instance()属于discuz_core类在class_core.php
function &instance() {
static $object;
if(empty($object)) {
  $object = new discuz_core();
}
return $object;
}
[/code]
这里保证单词请求都运用一个discuz_core实例。这里的&写法是为了兼容PHP4的，如果在PHP5中，则可以使用static。
[code language=php]
//这里是单件模式的简单例子。
class PHPig {
private static $v = null;
static function instance() {
  if(self::$v == null) {
   self::$v = new PHPig();
  }
  return self::$v;
}
}
$pig1 = PHPig::instance();
$pig2 = PHPig::instance();
if($pig1 === $pig2) {
echo '同一个对象';
} else {
echo '不是同一个对象';
}
[/code]

<?
 $host = "www.111cn.net";
 $path = "/Report.php?ReportID=1";
 $cookie = Session_id();
 
 $fp = fsockopen($host, 80, $errno, $errstr, 30);
 if (!$fp) {
    print "$errstr ($errno)<br />n";
    exit;
 }
 $out = "GET ".$path." HTTP/1.1rn";
 $out .= "Host: ".$host."rn";
 $out .= "Connection: Closern";
 $out .= "Cookie: ".$cookie."rnrn";
 
 fwrite($fp, $out);  //将请求写入socket
 //也可以选择获取server端的响应
 /*while (!feof($fp)) {
     echo fgets($fp, 128);
 }*/
 //如果不等待server端响应直接关闭socket即可
 fclose($fp);
 ?>

<?php
 ignore_user_abort(true);
 set_time_limit(0);
 
 while(1) {
 　　$fp  = fopen('time_task.txt',"a+");
 　　$str = date("Y-m-d h:i:s")."nr";
 　　fwrite($fp,$str);
 　　fclose($fp);
 　　sleep(5);    //半小时执行一次
 }
 ?>