// http请求类的接口

interface Proto {

    // 连接url

    function conn($url);

    //发送get查询

    function get();

    // 发送post查询

    function post();

    // 关闭连接

    function close();

}

class Http implements Proto {

    const CRLF  = "\r\n";

    protected $errno = -1;

    protected $errstr = '';

    protected $response = '';

    protected $url = null;

    protected $version = 'HTTP/1.1';

    protected $fh = null;

    protected $line = array();

    protected $header = array();

    protected $body = array();

    public function __construct($url) {

        $this->conn($url);

        $this->setHeader('Host: ' . $this->url['host']);

    }

    // 此方法负责写请求行

    protected function setLine($method) {

        $this->line[0] = $method . ' ' . $this->url['path'] . '?' .$this->url['query'] . ' '. $this->version;

    }

    // 此方法负责写头信息

    public function setHeader($headerline) {

        $this->header[] = $headerline;

    }

    // 此方法负责写主体信息

    protected function setBody($body) {

         $this->body[] = http_build_query($body);

    }

    // 连接url

    public function conn($url) {

        $this->url = parse_url($url);

        //　判断端口

        if(!isset($this->url['port'])) {

            $this->url['port'] = 80;

        }

        //　判断query

        if(!isset($this->url['query'])) {

            $this->url['query'] = '';

        }

        $this->fh = fsockopen($this->url['host'],$this->url['port'],$this->errno,$this->errstr,3);

    }

    //构造get请求的数据

    public function get() {

        $this->setLine('GET');

        $this->request();

        return $this->response;

    }

    // 构造post查询的数据

    public function post($body = array()) {

        $this->setLine('POST');

        // 设计content-type

        $this->setHeader('Content-type: application/x-www-form-urlencoded');

        // 设计主体信息,比GET不一样的地方

        $this->setBody($body);

        // 计算content-length

        $this->setHeader('Content-length: ' . strlen($this->body[0]));

        $this->request();

        return $this->response;

    }

    // 真正请求

    public function request() {

        // 把请求行，头信息，实体信息　放在一个数组里，便于拼接

        $req = array_merge($this->line,$this->header,array(''),$this->body,array(''));

        //print_r($req);

        $req = implode(self::CRLF,$req);

        //echo $req; exit;

        fwrite($this->fh,$req);

        while(!feof($this->fh)) {

            $this->response .= fread($this->fh,1024);

        }

        $this->close(); //　关闭连接

    }

    // 关闭连接

    public function close() {

        fclose($this->fh);

    }

}

$http = new Http('http://localhost/apple.jpg'); //本机服务器www目录下的apple.jpg图片

$http->setHeader('Referer: http://localhost');  //构造Referer信息

$res = $http->get();

//print_r($res);

file_put_contents('./aa.png',substr(strstr($res,"\r\n\r\n"),4));