php实现文件下载功能

直接上代码:

请求路径:http://根目录?m=Jwgl&c=excellentCourse&a=downloadFile&filename=文件名;

//文件下载
public function downloadFile() {
    $file_name = $_GET["filename"];
    $file_path = "uploads/excellentCourse/".$file_name;
    if (!file_exists($file_path))
    {
        echo '<script type="text/javascript">alert("文件不存在");window.history.back();</script>';
        exit();
    }
    $fp = fopen($file_path, "r");
    $file_size = filesize($file_path);

    header("Content-type: application/octet-stream");
    header("Accept-Ranges: bytes");
    header("Accept-Length:".$file_size);
    header("Content-Disposition: attachment;filename=".$file_name);
    $buffer = 1024;
    $file_count = 0;
    while (!feof($fp) && ($file_size > $file_count))
    {
        $file_data = fread($fp, $buffer);
        $file_count += $buffer;
        echo $file_data;
    }
    fclose($fp);
}