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PHP实现下载断点续传的方法_PHP

May 31, 2016 pm 07:28 PM
php download http

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:

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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