<?php

  $postdata = array('name'=>'niutian365','pass'=>'123456***') ;/*要访问的页面上的form内的input名称参数或者get参数*/

  $post_string =  http_build_query($postdata);
  $opts = array(
'http'=>array(
  'protocol_version'=>'1.1',/*http协议版本(若不指定php5.2系默认为http1.0)*/
  'method'=>"POST",/*获取方式这里可改成GET*/
  'timeout' => 5 ,/*超时时间*/
  'header'=>
          "User-Agent:Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN; rv:1.9.2.8) Gecko/20100722 Firefox/3.6.8\r\n".
          "Accept:text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8\r\n".
          "Accept-language: zh-cn,zh;q=0.5\r\n" .
      "Accept-Charset: GB2312,utf-8;q=0.7,*;q=0.7\r\n".
      "Content-length: ".strlen($post_string),/*模拟的header头*/
   'content'=> $post_string /*访问时传递的数据内容*/
    )
  );

  /*创建并返回一个文本数据流并应用各种选项,
      可用于fopen(),file_get_contents()等过程的超时设置,
      代理服务器,请求方式,头信息设置的特殊过程
  */
  $context = stream_context_create($opts);

  $content = file_get_contents('http://www.niutian365.com/index.php',false,$context );
?>

其他方式(来自网络未验证)：

<?php
/**
* Socket版本
* 使用方法：
* $post_string = "app=socket&version=beta";
* request_by_socket('facebook.cn','/restServer.php',$post_string);
*/
function request_by_socket($remote_server,$remote_path,$post_string,$port = 80,$timeout = 30){
    $socket = fsockopen($remote_server,$port,$errno,$errstr,$timeout);
    if (!$socket) die("$errstr($errno)");

    fwrite($socket,"POST $remote_path HTTP/1.0\r\n");
    //fwrite($socket,"User-Agent: Socket Example\r\n");
    fwrite($socket,"User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN; rv:1.9.1.2) Gecko/20090729 Firefox/3.5.2\r\n");
    fwrite($socket,"HOST: $remote_server\r\n");
    fwrite($socket,"Content-type: application/x-www-form-urlencoded\r\n");
    fwrite($socket,"Content-length: ".strlen($post_string) ."\r\n");
    fwrite($socket,"Accept:*/*\r\n");
    fwrite($socket,"\r\n");
    fwrite($socket,$post_string."\r\n");
    fwrite($socket,"\r\n");

    $header = "";//去除头部
    while ($str = trim(fgets($socket,4096))) {
        $header.=$str;
    }

    $data = "";
    while (!feof($socket)) {
        $data .= fgets($socket,4096);
    }

    return $data;
}

/**
* Curl版本
* 使用方法：
* $post_string = "app=request&version=beta";
* request_by_curl('http://facebook.cn/restServer.php',$post_string);
*/
function request_by_curl($remote_server,$post_string){
    $ch = curl_init();
    curl_setopt($ch,CURLOPT_URL,$remote_server);
    curl_setopt($ch,CURLOPT_POSTFIELDS,$post_string);
    curl_setopt($ch,CURLOPT_RETURNTRANSFER,true);
    curl_setopt($ch,CURLOPT_USERAGENT,'Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN; rv:1.9.1.2) Gecko/20090729 Firefox/3.5.2');
    $data = curl_exec($ch);
    curl_close($ch);
    return $data;
}
?>