Detailed introduction to the implementation of three file downloads in PHP

This article will give you a detailed introduction to the implementation of three kinds of file downloads in PHP, which has certain reference value. Friends in need can refer to it. I hope it helps everyone.

1. Add the file link directly

<button>
    <a href = "http://localhost/down.zip">
    下载文件</button>

Click the button to download ：

2. Pass parameters to search and jump to the download link

Pass parameters:

<button>
    <a href = "http://localhost?f=&#39;down&#39;">
    下载文件
</button>

Find the file and challenge to the download link:

<?php

$down = $_GET[&#39;f&#39;];   //获取文件参数
$filename = $down.&#39;.zip&#39;; //获取文件名称
$dir ="down/";  //相对于网站根目录的下载目录路径
$down_host = $_SERVER[&#39;HTTP_HOST&#39;].&#39;/&#39;; //当前域名


//判断如果文件存在,则跳转到下载路径
if(file_exists(__DIR__.&#39;/&#39;.$dir.$filename)){
    header(&#39;location:http://&#39;.$down_host.$dir.$filename);
}else{
    header(&#39;HTTP/1.1 404 Not Found&#39;);
}

Result:

• File Exists

• File does not exist
  

3. The head() and fread() functions output the file directly to the browser

<?php  
$file_name = "down";$file_name = "down.zip";     //下载文件名    $file_dir = "./down/";        //下载文件存放目录    //检查文件是否存在    if (! file_exists ( $file_dir . $file_name )) {    
    header(&#39;HTTP/1.1 404 NOT FOUND&#39;);  
} else {    
    //以只读和二进制模式打开文件   
    $file = fopen ( $file_dir . $file_name, "rb" ); 

    //告诉浏览器这是一个文件流格式的文件    
    Header ( "Content-type: application/octet-stream" ); 
    //请求范围的度量单位  
    Header ( "Accept-Ranges: bytes" );  
    //Content-Length是指定包含于请求或响应中数据的字节长度    
    Header ( "Accept-Length: " . filesize ( $file_dir . $file_name ) );  
    //用来告诉浏览器，文件是可以当做附件被下载，下载后的文件名称为$file_name该变量的值。
    Header ( "Content-Disposition: attachment; filename=" . $file_name );    

    //读取文件内容并直接输出到浏览器    
    echo fread ( $file, filesize ( $file_dir . $file_name ) );    
    fclose ( $file );    
    exit ();    
}

The result: the same as the second one

Summary: The first and second operations are relatively simple, but they are easy to expose the real address of the file and are not very secure. The third operation can better hide the real address of the file

Recommended learning: php video tutorial

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