如何使用php发出post请求使用curl保持会话活动

我正在使用php抓取需要会话才能登录的WWW.Example.com。我已经使用php curl成功登录。 请检查此链接。现在在该链接中，它显示了如何使用相同的会话cookie发出第二个请求

我的问题是刮伤的时候

define("COOKIE_FILE", "cookie.txt");  
    // Login the user  
    $ch = curl_init('http://api.example.com/login/joe/smith');  
    curl_setopt ($ch, CURLOPT_COOKIEJAR, COOKIE_FILE);   
    curl_setopt ($ch, CURLOPT_RETURNTRANSFER, true);  
    curl_setopt($ch, CURLOPT_HEADER, true);  
    echo curl_exec ($ch);

    // Read the session saved in the cookie file  
    echo "<br/><br/>";  
    $file = fopen("cookie.txt", 'r');
    echo fread($file, 100000000);     
    echo "<br/><br/>";

    // Get the users details
    $ch = curl_init('http://api.example.com/user');
    curl_setopt ($ch, CURLOPT_COOKIEJAR, COOKIE_FILE); 
    curl_setopt ($ch, CURLOPT_COOKIEFILE, COOKIE_FILE); 
    curl_setopt ($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_HEADER, true);
    echo curl_exec ($ch);

当第二个请求是GET请求时，一切都运行得非常好。当涉及到POST请求时，网站返回“您的会话已过期，请重新登录”

如何解决这个问题？我尝试了几种解决方案，在谷歌上搜索了一下，什么都没用。最后决定在这里发帖。提前谢谢

define("COOKIE_FILE", "cookie.txt");
    // Login the user
    $ch = curl_init('http://api.example.com/login/joe/smith');
    curl_setopt ($ch, CURLOPT_COOKIEJAR, COOKIE_FILE); 
    curl_setopt ($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_HEADER, true);
    echo curl_exec ($ch);

    // Read the session saved in the cookie file
    echo "<br/><br/>";
    $file = fopen("cookie.txt", 'r');
    echo fread($file, 100000000);   
    echo "<br/><br/>";

    // Get the users details
    $ch = curl_init('http://api.example.com/user');
    curl_setopt ($ch, CURLOPT_COOKIEJAR, COOKIE_FILE); 
    curl_setopt ($ch, CURLOPT_COOKIEFILE, COOKIE_FILE); 
    curl_setopt ($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_HEADER, true);
    curl_setopt($ch, CURLOPT_POST, true);
    curl_setopt($ch, CURLOPT_POSTFIELDS, 'username=abc&password=xyz&domain=123');
    echo curl_exec ($ch);

# Netscape HTTP Cookie File # https://curl.haxx.se/docs/http-cookies.html # This file was generated by libcurl! Edit at your own risk. www.example.com  FALSE   /unifyv3    FALSE   0 JSESSIONID    5366C3DB90DE7187A66E0BD19F595309 

HTTP/1.1 200 OK Date: Fri, 05 Aug 2016 19:48:25 GMT Server: Apache/2.2.3 (CentOS) Set-Cookie: JSESSIONID=225D8E499DE23F0FDF454D73F0C05F25; Path=/unifyv3 Content-Length: 2850 Connection: close Content-Type: text/html;charset=UTF-8
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