Detailed explanation of CURL for PHP web crawler

<?php/**
 * 实例描述：在网络上下载一个网页并把内容中的“百度”替换为“屌丝”之后输出
 */$curlobj = curl_init();            // 初始化curl_setopt($curlobj, CURLOPT_URL, "http://www.baidu.com");        // 设置访问网页的URLcurl_setopt($curlobj, CURLOPT_RETURNTRANSFER, true);           // 执行之后不直接打印出来$output=curl_exec($curlobj);  // 执行curl_close($curlobj);          // 关闭cURLecho str_replace("百度","屌丝",$output);?>

<?php/**
 * 实例描述：通过调用WebService查询北京的当前天气
 */$data = &#39;theCityName=北京&#39;;$curlobj = curl_init();    
curl_setopt($curlobj, CURLOPT_URL, "http://www.webxml.com.cn/WebServices/WeatherWebService.asmx/getWeatherbyCityName");  
curl_setopt($curlobj, CURLOPT_HEADER, 0); 
curl_setopt($curlobj, CURLOPT_RETURNTRANSFER, 1);  
curl_setopt($curlobj, CURLOPT_POST, 1);  
curl_setopt($curlobj, CURLOPT_POSTFIELDS, $data);  
curl_setopt($curlobj, CURLOPT_HTTPHEADER, array("application/x-www-form-urlencoded; charset=utf-8", 
    "Content-length: ".strlen($data)
    )); 
$rtn = curl_exec($curlobj);   
if(!curl_errno($curlobj)){    // $info = curl_getinfo($curlobj); 
    // print_r($info);
    echo $rtn;  
} else {  echo &#39;Curl error: &#39; . curl_error($curlobj);
}
curl_close($curlobj);?>

<?php/**
 * 实例描述：模拟需要登录的网址并抓取网页的内容
 */$data=array(&#39;username&#39; => &#39;promonkey&#39;, 
    &#39;password&#39; => &#39;1q2w3e&#39;,    &#39;remember&#39;=>1);$data=&#39;username=zjzhoufy@126.com&password=1q2w3e&remember=1&#39;;$curlobj = curl_init();            // 初始化curl_setopt($curlobj, CURLOPT_URL, "http://www.imooc.com/user/login");     // 设置访问网页的URLcurl_setopt($curlobj, CURLOPT_RETURNTRANSFER, true);           // 执行之后不直接打印出来// Cookie相关设置，这部分设置需要在所有会话开始之前设置date_default_timezone_set(&#39;PRC&#39;); // 使用Cookie时，必须先设置时区curl_setopt($curlobj, CURLOPT_COOKIESESSION, TRUE); 
curl_setopt($curlobj, CURLOPT_HEADER, 0); 
curl_setopt($curlobj, CURLOPT_FOLLOWLOCATION, 1); // 这样能够让cURL支持页面链接跳转curl_setopt($curlobj, CURLOPT_POST, 1);  
curl_setopt($curlobj, CURLOPT_POSTFIELDS, $data);  
curl_setopt($curlobj, CURLOPT_HTTPHEADER, array("application/x-www-form-urlencoded; charset=utf-8", 
    "Content-length: ".strlen($data)
    )); 
curl_exec($curlobj);   // 执行curl_setopt($curlobj, CURLOPT_URL, "http://www.imooc.com/space/index");
curl_setopt($curlobj, CURLOPT_POST, 0);  
curl_setopt($curlobj, CURLOPT_HTTPHEADER, array("Content-type: text/xml"
    )); 
$output=curl_exec($curlobj);  // 执行curl_close($curlobj);          // 关闭cURLecho $output;?>

<?php/**
 * 实例描述：登录网站的信息抓取并下载个人空间页面
 * 自定义实现页面链接跳转抓取
 * 
 */$data=&#39;username=demo_peter@126.com&password=123qwe&remember=1&#39;;$curlobj = curl_init();            // 初始化curl_setopt($curlobj, CURLOPT_URL, "http://www.imooc.com/user/login");     // 设置访问网页的URLcurl_setopt($curlobj, CURLOPT_RETURNTRANSFER, true);           // 执行之后不直接打印出来// Cookie相关设置，这部分设置需要在所有会话开始之前设置date_default_timezone_set(&#39;PRC&#39;); // 使用Cookie时，必须先设置时区curl_setopt($curlobj, CURLOPT_COOKIESESSION, TRUE); 
curl_setopt($curlobj, CURLOPT_HEADER, 0); 
// 注释掉这行，因为这个设置必须关闭安全模式 以及关闭open_basedir，对服务器安全不利//curl_setopt($curlobj, CURLOPT_FOLLOWLOCATION, 1);  curl_setopt($curlobj, CURLOPT_POST, 1);  
curl_setopt($curlobj, CURLOPT_POSTFIELDS, $data);  
curl_setopt($curlobj, CURLOPT_HTTPHEADER, array("application/x-www-form-urlencoded; charset=utf-8", 
    "Content-length: ".strlen($data)
    )); 
curl_exec($curlobj);   // 执行curl_setopt($curlobj, CURLOPT_URL, "http://www.imooc.com/space/index");
curl_setopt($curlobj, CURLOPT_POST, 0);  
curl_setopt($curlobj, CURLOPT_HTTPHEADER, array("Content-type: text/xml"
    )); 
$output=curl_redir_exec($curlobj);  // 执行curl_close($curlobj);          // 关闭cURLecho $output;/**
 * 自定义实现页面链接跳转抓取
 */function curl_redir_exec($ch,$debug="") { 
    static $curl_loops = 0; 
    static $curl_max_loops = 20; 

    if ($curl_loops++ >= $curl_max_loops) 
    { 
        $curl_loops = 0; 
        return FALSE; 
    } 
    curl_setopt($ch, CURLOPT_HEADER, true); // 开启header才能够抓取到重定向到的新URL
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true); 
    $data = curl_exec($ch); 
    // 分割返回的内容
    $h_len = curl_getinfo($ch, CURLINFO_HEADER_SIZE); 
    $header = substr($data,0,$h_len);    $data = substr($data,$h_len - 1);    $http_code = curl_getinfo($ch, CURLINFO_HTTP_CODE); 
    if ($http_code == 301 || $http_code == 302) { 
        $matches = array(); 
        preg_match(&#39;/Location:(.*?)\n/&#39;, $header, $matches); 
        $url = @parse_url(trim(array_pop($matches))); 
        // print_r($url); 
        if (!$url) 
        { 
            //couldn&#39;t process the url to redirect to 
            $curl_loops = 0; 
            return $data; 
        } 
        $last_url = parse_url(curl_getinfo($ch, CURLINFO_EFFECTIVE_URL)); 
        if (!isset($url[&#39;scheme&#39;])) 
            $url[&#39;scheme&#39;] = $last_url[&#39;scheme&#39;]; 
        if (!isset($url[&#39;host&#39;])) 
            $url[&#39;host&#39;] = $last_url[&#39;host&#39;]; 
        if (!isset($url[&#39;path&#39;])) 
            $url[&#39;path&#39;] = $last_url[&#39;path&#39;];        $new_url = $url[&#39;scheme&#39;] . &#39;://&#39; . $url[&#39;host&#39;] . $url[&#39;path&#39;] . (isset($url[&#39;query&#39;])?&#39;?&#39;.$url[&#39;query&#39;]:&#39;&#39;); 
        curl_setopt($ch, CURLOPT_URL, $new_url); 

        return curl_redir_exec($ch); 
    } else { 
        $curl_loops=0; 
        return $data; 
    } 
} 
?>

<?php/**
 * 实例描述：把本地文件上传到FTP服务器上
 */$curlobj = curl_init();    
$localfile = &#39;ftp01.php&#39;;$fp = fopen($localfile, &#39;r&#39;);

curl_setopt($curlobj, CURLOPT_URL, "ftp://192.168.1.100/ftp01_uploaded.php");  
curl_setopt($curlobj, CURLOPT_HEADER, 0); 
curl_setopt($curlobj, CURLOPT_RETURNTRANSFER, 1);  
curl_setopt($curlobj, CURLOPT_TIMEOUT, 300); // times out after 300scurl_setopt($curlobj, CURLOPT_USERPWD, "peter.zhou:123456");//FTP用户名：密码//上传和下载主要是下面子三个参数不一样curl_setopt($curlobj, CURLOPT_UPLOAD, 1);
curl_setopt($curlobj, CURLOPT_INFILE, $fp);
curl_setopt($curlobj, CURLOPT_INFILESIZE, filesize($localfile));$rtn = curl_exec($curlobj);  
fclose($fp); 
if(!curl_errno($curlobj)){    echo "Uploaded successfully.";  
} else {  echo &#39;Curl error: &#39; . curl_error($curlobj);
}
curl_close($curlobj);?>

<?php/**
 * 实例描述：下载网络上面的一个HTTPS的资源
 */$curlobj = curl_init();           
  // 初始化curl_setopt($curlobj, CURLOPT_URL, "https://ajax.aspnetcdn.com/ajax/jquery.validate/1.12.0/jquery.validate.js");      
   // 设置访问网页的URLcurl_setopt($curlobj, CURLOPT_RETURNTRANSFER, true);           
   // 执行之后不直接打印出来// 设置HTTPS支持date_default_timezone_set(&#39;PRC&#39;); 
   // 使用Cookie时，必须先设置时区curl_setopt($curlobj, CURLOPT_SSL_VERIFYPEER, 0); 
   // 对认证证书来源的检查从证书中检查SSL加密算法是否存在curl_setopt($curlobj, CURLOPT_SSL_VERIFYHOST, 2); 
   // $output=curl_exec($curlobj);  // 执行curl_close($curlobj);          
   // 关闭cURLecho $output;?>