How to deal with file upload and download problems in PHP development

How to deal with file upload and download issues in PHP development

In PHP development, file upload and download are common functional requirements. This article will introduce how to deal with file upload and download problems in PHP development, and provide specific code examples to help readers get started quickly.

1. File upload

1. Create upload form

First, you need to create an upload form on the page so that users can select and upload files. You can use the HTML

tag to create a form, and specify the form's enctype attribute as "multipart/form-data" to support file upload.

<form action="upload.php" method="post" enctype="multipart/form-data">
    <input type="file" name="file">
    <input type="submit" value="上传">
</form>

2. Processing upload requests

After receiving the upload request, you need to write a PHP script to handle the file upload operation. You can use the $_FILES array to obtain relevant information about the uploaded file, such as file name, temporary file path, etc.

<?php
if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    $file = $_FILES['file'];

    // 获取文件名
    $filename = $file['name'];

    // 获取文件的临时路径
    $tmpPath = $file['tmp_name'];

    // 处理文件上传操作，如将文件移动到指定目录
    $targetPath = 'uploads/' . $filename;
    move_uploaded_file($tmpPath, $targetPath);

    echo "文件上传成功！";
}
?>

In the above code, the uploaded file is moved to the "uploads" directory, and the file name remains unchanged.

2. File download

1. Provide download link

First of all, a download link needs to be provided on the page. Users can download the file when they click the link. . You can use the tag of HTML to create a download link, set the href attribute to the URL of the download script, and pass the file name as a parameter.

<a href="download.php?filename=file.txt">下载文件</a>

2. Processing download requests

After receiving the download request, you also need to write a PHP script to handle the file download operation. You can tell the browser to download the file as an attachment by reading the file content and setting the response header.

<?php
if ($_SERVER['REQUEST_METHOD'] === 'GET') {
    $filename = $_GET['filename'];
    $filePath = 'uploads/' . $filename;

    if (file_exists($filePath)) {
        header('Content-Description: File Transfer');
        header('Content-Type: application/octet-stream');
        header('Content-Disposition: attachment; filename=' . basename($filePath));
        header('Content-Transfer-Encoding: binary');
        header('Expires: 0');
        header('Cache-Control: must-revalidate');
        header('Pragma: public');
        header('Content-Length: ' . filesize($filePath));

        readfile($filePath);
        exit;
    } else {
        echo "文件不存在！";
    }
}
?>

In the above code, the contents of the file are read and output to the browser.

Summary:

Through the above steps, we can easily implement the file upload and download functions in PHP development. When uploading files, we need to create an upload form and write a PHP script to handle the upload operation. When downloading a file, we need to provide a download link and write a PHP script to handle the download operation. The above sample code can help readers quickly understand and apply the file upload and download functions.

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