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PHP uses header to implement file download function

墨辰丷

May 17, 2018 pm 02:13 PM

headerphpDownload Document

This article mainly introduces the use of header method in PHP to implement the file download function. It is very good and has reference value. Friends who need it can refer to it.

Let me introduce PHP to you first. header() function

#Definition and usage

header() function sends the original HTTP header to the client.

It's important to realize that the header() function must be called before any actual output is sent (in PHP 4 and above, you can use output caching to solve this problem):

<html>
<?php
// 结果出错
// 在调用 header() 之前已存在输出
header(&#39;Location: http://www.example.com/&#39;);
?>

Grammar

header(string,replace,http_response_code)

Number	Description
string	Required. Specifies the header string to be sent.
replace	Optional. Indicates whether this header replaces the previous header, or adds a second header. The default is true (replacement). false (allow multiple headers of the same type).
http_response_code	可选。把 HTTP 响应代码强制为指定的值。（PHP 4 以及更高版本可用）

Number

Description

string

Required. Specifies the header string to be sent.

replace

Optional. Indicates whether this header replaces the previous header, or adds a second header.

The default is true (replacement). false (allow multiple headers of the same type).

http_response_code

可选。把 HTTP 响应代码强制为指定的值。（PHP 4 以及更高版本可用）

php文件下载可以使用http的请求头加上php的IO可以实现，很久之前写过这么一个功能，后来代码没了，今天记录一下

1、先看一下一个正常的http请求

HTTP/1.1 200 OK
Server: Tengine
Content-Type: application/octet-stream
Content-Length: 5050697
Connection: keep-alive
Date: Thu, 12 Oct 2017 11:24:46 GMT
Accept-Ranges: bytes
Content-Disposition: attachment; filename=down/20170928/zjbb_2.9.5.apk
Expires: Thu, 12 Oct 2017 11:25:46 GMT
Cache-Control: max-age=60
Via: cache25.l2eu6-1[0,200-0,H], cache16.l2eu6-1[16,0], cache8.cn891[0,200-0,H], cache8.cn891[1,0]
Age: 1733678
X-Cache: HIT TCP_MEM_HIT dirn:6:277104755 mlen:-1
X-Swift-SaveTime: Sat, 14 Oct 2017 00:50:47 GMT
X-Swift-CacheTime: 93312000
Timing-Allow-Origin: *
EagleId: b73d0e1c15095411645886178e

2、一些常见的header功能

header(&#39;HTTP/1.1 200 OK&#39;); // ok 正常访问
header(&#39;HTTP/1.1 404 Not Found&#39;); //通知浏览器 页面不存在
header(&#39;HTTP/1.1 301 Moved Permanently&#39;); //设置地址被永久的重定向 301
header(&#39;Location: http://www.test.con/&#39;); //跳转到一个新的地址
header(&#39;Refresh: 10; url=http://www.test.con/&#39;); //延迟转向 也就是隔几秒跳转
header(&#39;X-Powered-By: PHP/7.0.0&#39;); //修改 X-Powered-By信息
header(&#39;Content-language: en&#39;); //文档语言
header(&#39;Content-Length: 1234&#39;); //设置内容长度
header(&#39;Last-Modified: &#39;.gmdate(&#39;D, d M Y H:i:s&#39;, $time).&#39; GMT&#39;); //告诉浏览器最后一次修改时间
header(&#39;HTTP/1.1 304 Not Modified&#39;); //告诉浏览器文档内容没有发生改变
###内容类型###
header(&#39;Content-Type: text/html; charset=utf-8&#39;); //网页编码
header(&#39;Content-Type: text/plain&#39;); //纯文本格式
header(&#39;Content-Type: image/jpeg&#39;); //JPG、JPEG
header(&#39;Content-Type: application/zip&#39;); // ZIP文件
header(&#39;Content-Type: application/pdf&#39;); // PDF文件
header(&#39;Content-Type: audio/mpeg&#39;); // 音频文件
header(&#39;Content-type: text/css&#39;); //css文件
header(&#39;Content-type: text/javascript&#39;); //js文件
header(&#39;Content-type: application/json&#39;); //json
header(&#39;Content-type: application/pdf&#39;); //pdf
header(&#39;Content-type: text/xml&#39;); //xml
header(&#39;Content-Type: application/x-shockw**e-flash&#39;); //Flash动画
######
###声明一个下载的文件###
header(&#39;Content-Type: application/octet-stream&#39;);
header(&#39;Content-Disposition: attachment; filename="ITblog.zip"&#39;);
header(&#39;Content-Transfer-Encoding: binary&#39;);
readfile(&#39;test.zip&#39;);
######
###对当前文档禁用缓存###
header(&#39;Cache-Control: no-cache, no-store, max-age=0, must-revalidate&#39;);
header(&#39;Expires: Mon, 26 Jul 1997 05:00:00 GMT&#39;);
######
###显示一个需要验证的登陆对话框###
header(&#39;HTTP/1.1 401 Unauthorized&#39;);
header(&#39;WWW-Authenticate: Basic realm="Top Secret"&#39;);
######
###声明一个需要下载的xls文件###
header(&#39;Content-Disposition: attachment; filename=abc.xlsx&#39;);
header(&#39;Content-Type: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet&#39;);
header(&#39;Content-Length: &#39;.filesize(&#39;./test.xls&#39;));
header(&#39;Content-Transfer-Encoding: binary&#39;);
header(&#39;Cache-Control: must-revalidate&#39;);
header(&#39;Pragma: public&#39;);
readfile(&#39;./test.xls&#39;);

3、看下下载所要用的的请求头

header("Content-type:application/octet-stream");
header("Accept-Ranges:bytes");
header("Accept-Length:".$file_Size);
header("Content-Disposition: attachment; filename=".$filename);

content-type：文件类型
Accept-Ranges：表示接收数据的类型或者范围，图片属于二进制的东西所以需要使用字节的方式传输
Accept-Length：表示接收的文件大小，php文件下载需要告诉浏览器下载的文件有多大
Content-Disposition：附件只需要把文件名给过去就可以，这个名称就是下载时显示的文件名称

4、php的文件操作出现的比较早，文件名是中文的时候需要注意转码

$filename=iconv("UTF-8","GB2312",$filename);

5、php的文件下载机制是首先nginx把文件信息读入服务器内存，然后使用请求头把文件二进制信息通过浏览器传给客户端

feof用来判断文件是否已经读到了末尾，fread用来把文件读入缓冲区，缓冲区的大小是1024，一边读取一边把数据输出到浏览器。为了下载的安全性每次读数据都进行字节的计数。文件读取完毕后关闭输入流

注意：

a、如果运行的过程中出现问题，可以清空（擦掉）输出缓冲区，使用下面的代码即可

ob_clean();

b、很多人喜欢用readfile，如果是大文件，可能会有问题

完整代码

<?php
 ob_clean();
 $action = $_GET[&#39;action&#39;];
 $filename = base64_decode($action);//传的参数encode了
 $filepath = &#39;/data/www/www.test.com/&#39;.$filename;
 if(!file_exists($filepath)){
  exit;
 }
 $fp=fopen($filepath,"r");
 $filesize=filesize($filepath);
 header("Content-type:application/octet-stream");
 header("Accept-Ranges:bytes");
 header("Accept-Length:".$filesize);
 header("Content-Disposition: attachment; filename=".$filename);
 $buffer=1024;
 $buffer_count=0;
 while(!feof($fp)&&$file_Size-$buffer_count>0){
 $data=fread($fp,$buffer);
 $buffer_count+=$buffer;
  echo $data;
 }
 fclose($fp);
?>

PS：下面看一段实例代码php如何通过header文件头实现文件下载

具体代码如下所示：

$file = $_GET[&#39;file&#39;];
if(file_exists($file)){
header("Content-type:application/octet-stream");
$filename = basename($file);
header("Content-Disposition:attachment;filename = ".$filename);
header("Accept-ranges:bytes");
header("Accept-length:".filesize($file));
readfile($file);
}else{
  echo "<script>alert(&#39;文件不存在&#39;)</script>";
}

相关推荐：

html中用href 实现点击链接弹出文件下载对话框

php实现支持中文的文件下载功能示例

Ajax实现文件下载功能详解

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