强制文件下载处理

Question

我试图了解如何为强制下载创建响应以及浏览器如何处理它。在此处关注本文：教程。我有一个发送文件作为下载响应的脚本。<?php// it's a zip fileheader('Content-Type: application/zip');// 1 million bytes (about 1megabyte)header('Content-Length: 1000000');// load a download dialogue, and save it as download.zipheader('Content-Disposition: attachment; filename="download.zip"');// 1000 times 1000 bytes of datafor ($i = 0; $i < 1000; $i++) {    echo str_repeat(".",1000);    // sleep to slow down the download    // sleep(5);}sleep(5);当sleep()函数在循环内时，它会在文件开始下载之前等待一段时间。但是当放在循环之外时，文件会立即开始下载。谁能帮我理解这种行为？

Answer 1

第二种情况的问题是在调用睡眠函数之前将文件发送给客户端。您可以将输出存储在内部缓冲区中，并在睡眠功能之后发送。（我不建议将其用于生产。）试试这个修改后的程序：

<?php

// it's a zip file

header('Content-Type: application/zip');

// 1 million bytes (about 1megabyte)

header('Content-Length: 1000000');

// load a download dialogue, and save it as download.zip

header('Content-Disposition: attachment; filename="download.zip"');

//Turn on output buffering

ob_start();

// 1000 times 1000 bytes of data

for ($i = 0; $i < 1000; $i++) {

    echo str_repeat(".",1000);

    // sleep to slow down the download

    // sleep(5);

}

//Store the contents of the output buffer

$buffer = ob_get_contents();

// Clean the output buffer and turn off output buffering

ob_end_clean();

sleep(5);

echo $buffer;