PHP实现下载断点续传的方法
这篇文章主要介绍了PHP实现下载断点续传的方法,通过自定义函数来实现PHP的断点续传下载方法,涉及文件的常见操作与指针和缓冲的用法,代码中备有较为详尽的注释便
本文实例讲述了PHP实现下载断点续传的方法。分享给大家供大家参考。
具体实现代码如下:
复制代码 代码如下:
/*
* PHP下载断点续传
*/
function dl_file_resume($file){
//检测文件是否存在
if (!is_file($file)) { die("404 File not found!"); }
$len = filesize($file);//获取文件大小
$filename = basename($file);//获取文件名字
$file_extension = strtolower(substr(strrchr($filename,"."),1));//获取文件扩展名
//根据扩展名 指出输出浏览器格式
switch( $file_extension ) {
case "exe": $ctype="application/octet-stream"; break;
case "zip": $ctype="application/zip"; break;
case "mp3": $ctype="audio/mpeg"; break;
case "mpg":$ctype="video/mpeg"; break;
case "avi": $ctype="video/x-msvideo"; break;
default: $ctype="application/force-download";
}
//Begin writing headers
header("Cache-Control:");
header("Cache-Control: public");
//设置输出浏览器格式
header("Content-Type: $ctype");
if (strstr($_SERVER['HTTP_USER_AGENT'], "MSIE")) {//如果是IE浏览器
# workaround for IE filename bug with multiple periods / multiple dots in filename
# that adds square brackets to filename - eg. setup.abc.exe becomes setup[1].abc.exe
$iefilename = preg_replace('/\./', '%2e', $filename, substr_count($filename, '.') - 1);
header("Content-Disposition: attachment; filename=\"$iefilename\"");
} else {
header("Content-Disposition: attachment; filename=\"$filename\"");
}
header("Accept-Ranges: bytes");
$size=filesize($file);
//如果有$_SERVER['HTTP_RANGE']参数
if(isset($_SERVER['HTTP_RANGE'])) {
/* ---------------------------
Range头域 Range头域可以请求实体的一个或者多个子范围。例如, 表示头500个字节:bytes=0-499 表示第二个500字节:bytes=500-999 表示最后500个字节:bytes=-500 表示500字节以后的范围:bytes=500- 第一个和最后一个字节:bytes=0-0,-1 同时指定几个范围:bytes=500-600,601-999 但是服务器可以忽略此请求头,如果无条件GET包含Range请求头,,响应会以状态码206(PartialContent)返回而不是以200 (OK)。
---------------------------*/
// 断点后再次连接 $_SERVER['HTTP_RANGE'] 的值 bytes=4390912-
list($a, $range)=explode("=",$_SERVER['HTTP_RANGE']);
//if yes, download missing part
str_replace($range, "-", $range);//这句干什么的呢。。。。
$size2=$size-1;//文件总字节数
$new_length=$size2-$range;//获取下次下载的长度
header("HTTP/1.1 206 Partial Content");
header("Content-Length: $new_length");//输入总长
header("Content-Range: bytes $range$size2/$size");//Content-Range: bytes 4908618-4988927/4988928 95%的时候
} else {//第一次连接
$size2=$size-1;
header("Content-Range: bytes 0-$size2/$size"); //Content-Range: bytes 0-4988927/4988928
header("Content-Length: ".$size);//输出总长
}
//打开文件
$fp=fopen("$file","rb");
//设置指针位置
fseek($fp,$range);
//虚幻输出
while(!feof($fp)){
//设置文件最长执行时间
set_time_limit(0);
print(fread($fp,1024*8));//输出文件
flush();//输出缓冲
ob_flush();
}
fclose($fp);
exit;
}
dl_file_resume("1.zip");//同级目录的1.zip 文件
//---------------------------------------
//不支持断点续传的文件下载。
//---------------------------------------
downFile("1.zip");
function downFile($sFilePath)
{
if(file_exists($sFilePath)){
$aFilePath=explode("/",str_replace("\\","/",$sFilePath),$sFilePath);
$sFileName=$aFilePath[count($aFilePath)-1];
$nFileSize=filesize ($sFilePath);
header ("Content-Disposition: attachment; filename=" . $sFileName);
header ("Content-Length: " . $nFileSize);
header ("Content-type: application/octet-stream");
readfile($sFilePath);
}
else
{
echo("文件不存在!");
}
}
?>
希望本文所述对大家的PHP程序设计有所帮助。

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