如何使用PHP安全上传文件？

使用 PHP 上传文件

在 PHP 中，上传文件的过程可以通过多种方法来实现。这是一个改进的 PHP 脚本，它结合了最佳实践并解决了您遇到的错误：

// Declare the target directory for uploaded files
$target_dir = "uploads/";

// Initialize an empty array for allowed file types
$allowedTypes = ['jpg', 'png'];

// Check if the form has been submitted
if (isset($_POST['submit'])) {
    // Retrieve the file details
    $target_file = $target_dir . basename($_FILES['fileToUpload']['name']);
    $file_type = strtolower(pathinfo($target_file, PATHINFO_EXTENSION));

    // Validate the file type
    if (!in_array($file_type, $allowedTypes)) {
        echo "Invalid file type. Only JPG and PNG files are allowed.";
    } 

    // Check if the file already exists
    elseif (file_exists($target_file)) {
        echo "File already exists. Please choose a different file.";
    } 

    // Check file size (assumes a 5MB limit)
    elseif ($_FILES['fileToUpload']['size'] > 5000000) {
        echo "File is too large. Maximum file size is 5MB.";
    } 

    else {
        // Attempt to move the file to the target directory
        if (move_uploaded_file($_FILES['fileToUpload']['tmp_name'], $target_file)) {
            echo "File uploaded successfully!";
        } else {
            echo "File upload failed. Please try again.";
        }
    }
}

?>

此脚本提供了改进的错误处理和验证机制，确保仅上传允许的文件类型并防止重复或过大的文件被接受。

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