在网上抓取一个图片保存到本地的php函数怎么写？

Question

$data=file_get_conents($url);
writetofile($address,$data);
function writetofile()
........

Answer 1

file_get_conents是读取字符串的，不是读二进制数据的，你可以用他读取网上的一个图片试试，失败的

Answer 2

下载phpbb，打开admin/admin_users.php文件研究。（本来把代码帖上来的，但太长，帖部分吧）
                        else if( !empty($user_avatar_url) )
                        {
                                //
                                // First check what port we should connect
                                // to, look for a :[xxxx]/ or, if that doesn't
                                // exist assume port 80 (http)
                                //
                                preg_match("/^(http:\/\/)?([\w\-\.]+)\:?([0-9]*)\/(.*)$/", $user_avatar_url, $url_ary);                                if( !empty($url_ary[4]) )
                                {
                                        $port = (!empty($url_ary[3])) ? $url_ary[3] : 80;                                        $fsock = @fsockopen($url_ary[2], $port, $errno, $errstr);
                                        if( $fsock )
                                        {
                                                $base_get = "/" . $url_ary[4];                                                //
                                                // Uses HTTP 1.1, could use HTTP 1.0 ...
                                                //
                                                @fputs($fsock, "GET $base_get HTTP/1.1\r\n");
                                                @fputs($fsock, "HOST: " . $url_ary[2] . "\r\n");
                                                @fputs($fsock, "Connection: close\r\n\r\n");                                                unset($avatar_data);
                                                while( !@feof($fsock) )
                                                {
                                                        $avatar_data .= @fread($fsock, $board_config['avatar_filesize']);
                                                }
                                                @fclose($fsock);                                                if( preg_match("/Content-Length\: ([0-9]+)[^\/ ][\s]+/i", $avatar_data, $file_data1) && preg_match("/Content-Type\: image\/[x\-]*([a-z]+)[\s]+/i", $avatar_data, $file_data2) )
                                                {
                                                        $file_size = $file_data1[1];
                                                        $file_type = $file_data2[1];                                                        switch( $file_type )
                                                        {
                                                                case "jpeg":
                                                                case "pjpeg":
                                                                case "jpg":
                                                                        $imgtype = '.jpg';
                                                                        break;
                                                                case "gif":
                                                                        $imgtype = '.gif';
                                                                        break;
                                                                case "png":
                                                                        $imgtype = '.png';
                                                                        break;
                                                                default:
                                                                        $error = true;
                                                                        $error_msg = (!empty($error_msg)) ? $error_msg . "<br />" . $lang['Avatar_filetype'] : $lang['Avatar_filetype'];
                                                                        break;
                                                        }                                                        if( !$error && $file_size > 0 && $file_size < $board_config['avatar_filesize'] )
                                                        {
                                                                $avatar_data = substr($avatar_data, strlen($avatar_data) - $file_size, $file_size);                                                                $tmp_filename = tempnam ("/tmp", $this_userdata['user_id'] . "-");
                                                                $fptr = @fopen($tmp_filename, "wb");
                                                                $bytes_written = @fwrite($fptr, $avatar_data, $file_size);
                                                                @fclose($fptr);                                                                if( $bytes_written == $file_size )
                                                                {
                                                                        list($width, $height) = @getimagesize($tmp_filename);                                                                        if( $width <= $board_config['avatar_max_width'] && $height <= $board_config['avatar_max_height'] )
                                                                        {
                                                                                $user_id = $this_userdata['user_id'];                                                                                $avatar_filename = $user_id . $imgtype;。直到
｝

Answer 3

file_get_contents
(PHP 4 >= 4.3.0, PHP 5)file_get_contents -- 将整个文件读入一个字符串
说明
string file_get_contents ( string filename [, int use_include_path [, resource context]] )
和 file() 一样，只除了 file_get_contents() 将文件返回为一个字符串。 file_get_contents() 函数是用来将文件的内容读入到一个字符串中的首选方法。如果操作系统支持还会使用内存映射技术来增强性能。 注: 该函数可安全用于二进制对象。提示: 如果“fopen wrappers”已经被激活，则在本函数中可以把 URL 作为文件名来使用。请参阅 fopen() 函数来获取怎样指定文件名的详细信息以及支持 URL 协议的附录 L列表。注: Context 支持是 PHP 5.0.0 新加的。

Answer 4

如果是linux系统 可以使用php运行系统命令wget

Answer 5

<?
$s=file_get_contents('http://community.csdn.net/images/CSDN_logo.GIF');
$fh=fopen('logo.gif','w');
fwrite($fh,$s);
fclose($fh);
?>
没问题唉，谁说不能保存二进制的？打PP

Answer 6

版本>5
file_get_contents.
file_put_contents就行了，

Answer 7

// ######### 获取远程文件的大小 #############################################################
// 范例：remote_image_upload("http://image2.sina.com.cn/sms/sinapic/27115050-index.jpg", "C:/apache/htdocs/1r1.jpg", 300000)
function remote_filesize($url)
{
$urlinfo = parse_url($url);
if ($urlinfo['scheme'] != 'http')
{
return false;
}
else if (empty($urlinfo['port']))
{
$urlinfo['port'] = 80;
}
if ($fp = fsockopen($urlinfo['host'], $urlinfo['port'], $errno, $errstr, 30))
{
fwrite($fp, 'HEAD ' . $url . " HTTP/1.1\r\n");
fwrite($fp, 'HOST: ' . $urlinfo['host'] . "\r\n");
fwrite($fp, "Connection: close\r\n\r\n");
while (!feof($fp))
{
$headers .= fgets($fp, 4096);
}
fclose ($fp);
$headersarray = explode("\n", $headers);
foreach($headersarray as $header)
{
if (strpos($header, 'Content-Length') === 0)
{
$matches = array();
preg_match('#(\d+)#', $header, $matches);
return sprintf('%u', $matches[0]);
}
}
return false;
}
else
{
return false;
}
}
// ########################################################################################// ######### 上传文件（文件来自远程文件） #################################
function remote_image_upload($url = '', $uploadfile, $maxsize)
{
$url = trim($url);
if ($url AND $url != 'http://www.')
{
if ($filesize = remote_filesize($url))
{
$filetolarge = false;
if ($filesize > $maxsize)
{
$filetolarge = true;
}
else
{
@ini_set('user_agent', 'PHP');
$handle = @fopen($url, 'rb');
if (!$handle)
{
return false;
}
while (!feof($handle))
{
$contents .= fread($handle, 8192);
if (strlen($contents) > $maxsize)
{
$filetolarge = true;
break;
}
}
fclose($handle);
}
if ($filetolarge OR (strlen($contents) > $maxsize))
{
return false;
}
}
else
{
return false;
}
$filename = tempnam(ini_get('upload_tmp_dir'), 'hzw');
$fp = @fopen($filename, 'wb');
@fwrite($fp, $contents);
@fclose($fp);
}
if (!file_exists($filename))
{
return false;
}
if (copy($filename, $uploadfile))
{
@unlink($filename);
     return true;
}
else
{
@unlink($filename);
     return false;
}
}
// ########################################################################################