使用header（）不能使用php下载Pdf文件

Question

我希望用户能够下载我服务器上的一些文件，但是当我尝试下载文件时显示如下错误。

码

 public function saveattachment(){
    $fn=$this->input->get_post('fn');
    $userid=$this->input->get_post('autherid');
    $file_url = realpath("./private").$userid."/".$fn;
    $file_name =basename($file_url);
    $ext = explode(".", $file_name);

    switch($ext[sizeof($ext)-1])
    {
        case 'jar': $mime = "application/java-archive"; break;
        case 'zip': $mime = "application/zip"; break;
        case 'jpeg': $mime = "image/jpeg"; break;
        case 'jpg': $mime = "image/jpg"; break;
        case 'jad': $mime = "text/vnd.sun.j2me.app-descriptor"; break;
        case "gif": $mime = "image/gif"; break;
        case "png": $mime = "image/png"; break;
        case "pdf": $mime = "application/pdf"; break;
        case "txt": $mime = "text/plain"; break;
        default: $mime = "application/force-download";
    }

    header('Content-Description: File Transfer');
    header('Content-Type: '.$mime);
    header('Content-Disposition: attachment; filename='.basename($file_name));
    header('Content-Transfer-Encoding: binary');
    header('Expires: 0');
    header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
    header('Pragma: public');
    header('Content-Length: ' . filesize($file_url));   
    ob_clean();
    flush();
    echo $file_url;
    }

文件已下载但未打开。

Answer 1

必须在发送任何实际输出之前调用

header（）， 示例代码

<?php
header("Content-type:application/pdf");

// It will be called file_name_for_download.pdf
header("Content-Disposition:attachment;filename='file_name_for_download.pdf'");

// The PDF source is file_for_read.pdf
readfile("file_for_read.pdf");
?>

在您的情况下使用基本代码并确保其正常工作，然后根据要求添加其他代码

Answer 2

将echo $file_url;替换为readfile($file_url);

Answer 3

我明白了。我编码为header('Content-Length: ' . filesize($file_url));，我将其替换为header('Content-Length: ' . filesize($file_name));。现在它的工作。谢谢你的时间来帮助我。