通过函数完成下载文件的PHP功能代码

function download($url, $filename) {    // 获得文件大小, 防止超过2G的文件, 用sprintf来读    $filesize = sprintf ( "%u", filesize ( $url ) );    if (! $filesize) {        return;    }    header ( "Content-type:application/octet-stream\n" ); //application/octet-stream    header ( "Content-type:unknown/unknown;" );    header ( "Content-disposition: attachment; filename=\"" . $filename . "\"" );    header ( 'Content-transfer-encoding: binary' );    if ($range = getenv ( 'HTTP_RANGE' )) { // 当有偏移量的时候，采用206的断点续传头        $range = explode ( '=', $range );        $range = $range [1];

        header ( "HTTP/1.1 206 Partial Content" );        header ( "Date: " . gmdate ( "D, d M Y H:i:s" ) . " GMT" );        header ( "Last-Modified: " . gmdate ( "D, d M Y H:i:s", filemtime ( $url ) ) . " GMT" );        header ( "Accept-Ranges: bytes" );        header ( "Content-Length:" . ($filesize - $range) );        header ( "Content-Range: bytes " . $range . ($filesize - 1) . "/" . $filesize );        header ( "Connection: close" . "\n\n" );    } else {        header ( "Content-Length:" . $filesize . "\n\n" );        $range = 0;    }    loadFile ( $url );}

function loadFile($filename, $retbytes = true) {    $buffer = '';    $cnt = 0;    $handle = fopen ( $filename, 'rb' );    if ($handle === false) {        return false;    }    while ( ! feof ( $handle ) ) {        $buffer = fread ( $handle, 1024 * 1024 );        echo $buffer;        ob_flush ();        flush ();        if ($retbytes) {            $cnt += strlen ( $buffer );        }    }    $status = fclose ( $handle );    if ($retbytes && $status) {        return $cnt; // return num. bytes delivered like readfile() does.    }    return $status;}输入2个参数即可完成下载

download($url, $filename)