How to use PHP PDF to realize that files can only be viewed but not downloaded

With the rapid development of the Internet, more and more people are beginning to use web pages to obtain information. In order to protect their intellectual property rights, many websites often choose to upload important files to the page in PDF format for visitors to view. However, for some files involving confidential information, website administrators usually do not want these files to be downloaded by unauthorized users. So, how to realize that PDF files can only be viewed on the web page and cannot be downloaded? This article will provide readers with relevant reference and guidance by introducing the method of php pdf realizing that the file can only be viewed but not downloaded.

1. Introduction to PHP PDF
PHP PDF is a technical means that can provide PDF format file viewing for web pages, and PHP is a widely used server-side scripting language that can be used with MySQL Integrate databases and other web technologies. By combining PHP with PDF, you can achieve very convenient PDF generation and processing operations, such as generating electronic invoices, generating PDF documents, data export, etc.

2. How to realize that PHP PDF files can only be viewed but not downloaded
To realize that PDF files can only be viewed on the web page but not downloaded requires some special technical means. Here are some practical methods:

1. Using .htaccess files
   The .htaccess file is an important file in the Apache server and can be used to manage the configuration of many websites and servers. The following code can be added to the .htaccess file to prevent the PDF file from being downloaded and directly accessed:

RewriteEngine on
RewriteCond %{HTTP_REFERER} !^$
RewriteCond %{HTTP_REFERER} !^http://(www.)?example.com/.*$ [NC]
RewriteRule .(pdf|PDF)$ - [F]

Here you need to change "example" to Your own domain name. This method is to limit the PDF file to be accessed only in the web page that references it. If the PDF file is accessed directly, the server will reject its request.

2. Convert PDF files to image format
If the PDF file format is not important, you can convert it to image format to protect the server from malicious users. PHP can convert PDF to many different image formats using tools such as ImageMagick and GhostScript.

3. Use file stream technology
File stream technology is a method that first reads the file content and returns it to the browser without saving the file locally. This technology effectively prevents PDF files from being downloaded directly to the user's computer.

The code is as follows:
<?php
$file1 = "demo1.pdf";
header("Content-type: application/pdf");
header(" Content-Disposition: inline; filename=\"$file1\"");
header("Content-Transfer-Encoding: binary");
header('Accept-Ranges: bytes');
@readfile($file1);
?>

Here you need to change $file1 to your file name. This method is suitable for smaller PDF files, because if the file is too large, the server may become slow or prone to crashing while reading the file.

By using the above technical means, we can realize that PDF files can only be viewed on the web page and cannot be downloaded. Using these technologies, you can effectively protect your intellectual property and avoid leakage of confidential information.

Conclusion:
PHP PDF is a very powerful technical means that can provide you with fast and convenient PDF file processing and management methods. For those PDF files that contain sensitive information, we can use some methods to ensure that these files can only be viewed on the web page and cannot be downloaded directly. This not only helps protect intellectual property but also provides visitors with a better visit experience.

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