How to implement large file upload and download in PHP

With the development of Internet technology, more and more application scenarios require the implementation of large file upload and download functions. In PHP applications, how to achieve efficient, stable and safe large file upload and download? Below we will introduce some practical tips and methods.

1. Large file upload

1. Partial upload

When uploading a large file, uploading the entire file at once is prone to network timeout, memory overflow, etc. problem, so using the multipart upload method is a better choice. Multipart upload can divide the file into several small chunks, upload them separately, and wait for all chunks to be uploaded before merging them into a complete file.

2. Defining the upload block size

It is very important to define the upload block size. Generally, the upload block size is set between 2MB and 10MB. Different The server and network environment can be adjusted according to actual conditions. An upload block that is too small will lead to frequent upload requests and increase the overhead of network requests; while an upload block that is too large will cause problems such as request timeout and memory overflow.

3. Use breakpoint resumable upload

In the process of uploading large files, it is common for network disconnection and unexpected browser closing to occur during the upload process. Therefore, Using breakpoint resume technology during upload can avoid re-uploading the entire file and improve upload efficiency. In PHP, you can use the range header to read the contents of the specified file interval to implement breakpoint resume upload, thereby realizing the partial upload function.

4. Limit the type and size of uploaded files

Limiting the type and size of uploaded files is very necessary to avoid uploading unsafe files and excessively large files that cause server crashes, etc. question. In PHP, you can easily obtain uploaded file information by using the $_FILES variable, limit the upload type by judging the file type, and limit the upload size by judging the file size.

5. Use multi-file upload

If you need to upload multiple large files at the same time, use multi-file upload to send multiple files at once to improve upload efficiency. In PHP, when using multiple file uploads, you need to define a separate tag for each uploaded file, and process the information of each uploaded file separately to ensure that each file is uploaded correctly. Overall efficiency.

2. Large file download

1. Enable compression technology

During the process of downloading large files, you can use compression technology to compress the downloaded file first and then Download, thereby reducing download file size and improving download efficiency and speed. In PHP, you can use the gzencode() function for file compression, and the header() function to transfer compressed files.

2. Use breakpoint resumption

During the download process, if problems such as network disconnection or browser closure occur, the downloaded data will be lost. Repeated downloads waste traffic and time. Therefore, using breakpoint resume download technology can avoid re-downloading the entire file and improve download efficiency. In PHP, when implementing breakpoint resume transmission, you need to set headers (headers) to implement the server's breakpoint resume transmission function.

3. File download speed limit

In the process of downloading large files, in some cases, a large amount of bandwidth will be occupied during the download process, causing other network requests to become Slow or even fail. Therefore, when downloading large files, you can implement the file download speed limiting function and limit the download rate. In PHP, you can use the sleep() function to control the download rate.

4. Use CDN to accelerate

When downloading files, using CDN can speed up the file transfer, thereby improving download speed and stability. CDN can store files on multiple servers, and users can download files from the server closest to them, which can reduce download time and reduce server load.

The above are some practical tips and methods for uploading and downloading large files in PHP, which can be adjusted and used according to your actual situation. In actual projects, you also need to pay attention to some security issues, such as preventing file upload vulnerabilities and malicious downloads, to ensure the security and stability of large file uploads and downloads.

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