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PHP 抓取網(wǎng)頁(yè)圖片并且另存為的實(shí)現(xiàn)代碼

更新時(shí)間：2010年03月24日 20:15:09 作者：

URL是遠(yuǎn)程的完整圖片地址，不能為空, $filename 是另存為的圖片名字默認(rèn)把圖片放在以此腳本相同的目錄里

下面是源代碼，及其相關(guān)解釋

 
<?php 
//URL是遠(yuǎn)程的完整圖片地址，不能為空, $filename 是另存為的圖片名字 
//默認(rèn)把圖片放在以此腳本相同的目錄里 
function GrabImage($url, $filename=""){ 
//$url 為空則返回 false; 
if($url == ""){return false;} 
$ext = strrchr($url, ".");//得到圖片的擴(kuò)展名 
if($ext != ".gif" && $ext != ".jpg" && $ext != ".bmp"){echo "格式不支持！";return false;} 
if($filename == ""){$filename = time()."$ext";}//以時(shí)間戳另起名 
//開(kāi)始捕捉 
ob_start(); 
readfile($url); 
$img = ob_get_contents(); 
ob_end_clean(); 
$size = strlen($img); 
$fp2 = fopen($filename , "a"); 
fwrite($fp2, $img); 
fclose($fp2); 
return $filename; 
} 
//測(cè)試 
GrabImage("http://www.dbjr.com.cn/images/logo.gif", "as.gif"); 
?> 

ob_start : 打開(kāi)輸出緩沖
This function will turn output buffering on. While output buffering is active no output is sent from the script (other than headers), instead the output is stored in an internal buffer. (輸出是在內(nèi)部緩沖儲(chǔ)存)
//
readfile : 讀入一個(gè)文件并寫(xiě)入到輸出緩沖
返回從文件中讀入的字節(jié)數(shù)。如果出錯(cuò)返回 FALSE 并且除非是以 @readfile() 形式調(diào)用，否則會(huì)顯示錯(cuò)誤信息。
//

ob_get_contents : Return the contents of the output buffer(返回輸出緩沖的內(nèi)容)
This will return the contents of the output buffer without clearing it or FALSE, if output buffering isn't active. (如果輸出緩沖沒(méi)有活動(dòng)（打開(kāi)），則返回 FALSE)
//
ob_end_clean() : Clean (erase) the output buffer and turn off output buffering(清除輸出緩沖)
This function discards(丟棄) the contents of the topmost output buffer and turns off this output buffering.(丟棄并且關(guān)掉) If you want to further process the buffer's contents you have to call ob_get_contents() before ob_end_clean() as the buffer contents are discarded when ob_end_clean() is called. （如果要用緩沖內(nèi)容，則在清理輸出緩沖之前要先調(diào)用 ob_get_contents()）The function returns TRUE when it successfully discarded one buffer and FALSE otherwise. Reasons for failure are first that you called the function without an active buffer or that for some reason a buffer could not be deleted (possible for special buffer).

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