為什麼我的文件下載識別不正確且出現延遲？

HTTP Headers for File Downloads: Troubleshooting Incorrect File Identification and Download Delays

Your PHP script is intended to handle file downloads by determining the requested file and setting appropriate HTTP headers to initiate a download rather than displaying the file in the browser. However, you've encountered an issue where specific files are being identified incorrectly, with the browser treating all files as GIF images.

Missing Content-Type Header

As suspected, the absence of the "Content-Type" header in the response may be the cause of the incorrect file identification. When a "Content-Type" is not specified, browsers often attempt to guess the file type based on the file extension. However, if the extension is missing or inaccurate, the browser may make an incorrect assumption.

Generic Content-Type for All Files

To address this issue, you can provide a generic "Content-Type" that applies to all files, regardless of their extensions. A common choice is "application/octet-stream" or "application/force-download." This indicates to the browser that the file is in an unspecified format and should be downloaded directly.

header('Content-Type: application/force-download');

Download Delay

Your updated implementation follows a more robust process for file downloads, but you've noticed a significant delay between when the script executes and when the browser's download dialog appears. To identify the bottleneck causing this delay, consider the following factors:

• Server Configuration: Check your server's configuration for settings that may affect file downloads, such as PHP memory limits, Apache's output buffering, or reverse proxy settings.
• Network Connection: Slow network connections can contribute to delays in file transfer. Monitor your network traffic and consider optimizing your connection for file downloads.
• Server Script Execution: Analyze your PHP script for performance bottlenecks. Check if there are any excessive processing operations that could slow down the script execution.
• File Size and Download Speed: The size of the file being downloaded can significantly impact the download time. Additionally, the speed of your Internet connection will affect the download speed.

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