php post请求和jquery中post请求有什么不同吗？该如何处理

php post请求和jquery中post请求有什么不同吗？
自己写了一个php的socket http请求，

PHP code

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public function sendpost($postType='POST')
    {
        $url = $this->postURL;
        $data = $this->postData == '' ? array() : $this->postData;
        //先解析url
        $url = parse_url($url);
        $url_port = !isset($url['port']) ? (($url['scheme'] == 'http') ? 80 : 443) : $url['port'];
        if (!$url)
        {
            $this->errMessage = "couldn't parse url";
            return false;
        }
        //将参数拼成URL key1=value1&key2=value2 的形式
        $encoded = "";
        while (list($k, $v) = each($data))
        {
            $encoded .= ($encoded ? '&' : '');
            $encoded .= rawurlencode($k)."=".rawurlencode($v);
        }
        //echo $encoded;exit;
        $len = strlen($encoded);
        //拼上http头
        $out = "{$postType} ".$url['path'].(isset($url['query']) ? ('?'.$url['query']) : '')." HTTP/1.1\r\n";
        $out .= "Host:".$url['host']."\r\n";
        $out .= "Content-type: application/x-www-form-urlencoded\r\n";
        $out .= "Connection: Close\r\n";
        $out .= "Content-Length: $len\r\n";
        $out .= "\r\n";
        $out .= $encoded."\r\n";
        //打开一个sock
        $fp = @fsockopen($url['host'], $url_port);
        $line = "";
        if (!$fp)
        {
            $this->errMessage = "$errstr($errno)\n";
            return false;
        }
        else
        {
            fwrite($fp,$out);
            while (!feof($fp))
            {
                $line .= fgets($fp, 2048);
            }
        }
        //去掉头文件
        if ($line)
        {
            $body = stristr($line, "\r\n\r\n");
            $body =substr($body, 4, strlen($body));
            $line = $body;
        }
        fclose($fp);
        return $line;
    }

同时，用jquery的ajax请求测试。

JScript code

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$.ajax({
                    type : "POST",
                    cache : false,
                    url : _url,
                    data : _data,
                    dataType : 'json',
                    success : function(data) {
                        
                    }
                });

发现php的请求总是返回错误的信息，而ajax请求则返回正确的，应该都是http post请求数据返回数据，没什么区别吧。
服务器端还可以检测出是ajax请求还是php请求？

------解决方案--------------------

PHP code

[User:root Time:03:17:09 Path:/home/apache/web]$ cat test.php 
<?php // http only, no error check.
function post_request($url, $data) {
        $post_data = http_build_query($data);
        $request = "POST /main.php HTTP/1.1\r\n" . 
                           "Host: 192.168.1.10\r\n" .
                           "Content-Type: application/x-www-form-urlencoded\r\n" .
                           "Content-Length: " . strlen($post_data) . "\r\n\r\n" .
                           $post_data;
        echo $request . PHP_EOL;
        $sockfd = fsockopen("192.168.1.10", 80);
        fwrite($sockfd, $request);
        $response = "";
        while (($ret= fgets($sockfd)) !== false) {
                $response .= $ret;
        }
        return $response;
}

$response = post_request("http://192.168.1.10/main.php", array('a' => "baidu", 'b' => "client backend"));
echo $response;
?>
[User:root Time:03:17:12 Path:/home/apache/web]$ cat main.php 
<?php echo $_POST['a'] . PHP_EOL;
echo $_POST['b'] . PHP_EOL;
?>
<br><font color="#e78608">------解决方案--------------------</font><br>另外，https你的代码是无力的，必须用php支持的context参数利用stream_context_create配合file_get_contents之类的使用或者fopen之类的使用，或者直接用curl。
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