求大神指导， php中 curl模拟post发送json并接收json，post数据不成功，也取不回json值

Question

代码放在本地做测试，一个简单的登录，但是curl post不过去数据，也取不回这个success

然后curl代码如下：

<?php
header("content-Type: text/html; charset=UTF-8");$login_url="http://127.0.0.3/35/doLogin.php";$data = array("username" => "demo", "password" => "demo","is_ajax"=>"1");                                                                    
$data_string = json_encode($data);//提交登录表单请求$ch=curl_init($login_url);
curl_setopt($ch,CURLOPT_HEADER,0);
curl_setopt($ch,CURLOPT_RETURNTRANSFER,0);
curl_setopt($ch,CURLOPT_POST,1);
curl_setopt($ch,CURLOPT_POSTFIELDS,$data_string);
curl_setopt($ch, CURLOPT_HTTPHEADER, array("X-Requested-With: XMLHttpRequest"));  
$data=curl_exec($ch);
curl_close($ch);

var_dump(json_decode($data,true));  
?>

访问curl代码打印出来是NULL 

Answer 1

$ch        = curl_init();        
$timeout   = 3;        
$useragent = "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)";        
$header    = array(                
                'Accept-Language: zh-cn', 
                'Connection: Keep-Alive', 
                'Cache-Control: no-cache', 
                'Content-Type: Application/json;charset=utf-8',
                "X-Requested-With: XMLHttpRequest"
            );
$login_url="http://127.0.0.3/35/doLogin.php";
$data = array("username" => "demo", "password" => "demo","is_ajax"=>"1");                                                                    
$json = json_encode($data);            
curl_setopt($ch, CURLOPT_HTTPHEADER, $header);
curl_setopt($ch, CURLOPT_USERAGENT, $useragent);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);        
curl_setopt($ch, CURLOPT_URL, $login_url);
curl_setopt($ch, CURLOPT_POST, TRUE);
curl_setopt($ch, CURLOPT_POSTFIELDS, $json);                        
curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, $timeout);            
$res = curl_exec($ch);        
echo '
';print_r(json_decode($res,true));