如何在 PHP 中限制文件上传类型的文件大小? [英] How to limit file upload type file size in PHP?

问题描述

我有一个上传表单，正在检查文件大小和文件类型，以将上传的文件限制为 2 兆字节和 .pdf、.jpg、.gif 或 .png 文件类型.我的目标是在用户违反这些规则之一时向用户显示警告消息.

I have an upload form and am checking the file size and file type to limit the uploaded file to 2 megabytes and either .pdf, .jpg, .gif or .png file types. My goal is to have an alert message displayed to the user if they violate one of these rules.

有四种情况:

1. 正确的尺寸/正确的类型(工作)
2. 正确的尺寸/不正确的类型(工作)
3. 尺寸不正确/类型正确(不起作用)
4. 不正确的尺寸/不正确的类型(不起作用)

使用我当前的代码，当文件大小大于 2 兆字节 (#4) 时，它总是显示不正确的类型"消息，即使文件类型正确 (#3).

With my current code, it always displays the incorrect "type" message when the file size is greater than 2 megabytes (#4), even if the file type is correct (#3).

知道为什么吗?

if (isset ( $_FILES['uploaded_file'] ) ) {

    $file_size = $_FILES['uploaded_file']['size'];
    $file_type = $_FILES['uploaded_file']['type'];

    if (($file_size > 2097152)){      
        $message = 'File too large. File must be less than 2 megabytes.'; 
        echo '<script type="text/javascript">alert("'.$message.'");</script>'; 
    }
    elseif (  
        ($file_type != "application/pdf") &&
        ($file_type != "image/jpeg") &&
        ($file_type != "image/jpg") &&
        ($file_type != "image/gif") &&
        ($file_type != "image/png")    
    ){
        $message = 'Invalid file type. Only PDF, JPG, GIF and PNG types are accepted.'; 
        echo '<script type="text/javascript">alert("'.$message.'");</script>';         
    }    
    else {
        store_uploaded_file($id);
    }

}   

推荐答案

您的代码未考虑到的问题是显示多个错误.正如您在上面提到的，用户上传的文件可能超过 2MB 的错误类型，但您的代码只能报告其中一个问题.尝试类似:

Something that your code doesn't account for is displaying multiple errors. As you have noted above it is possible for the user to upload a file >2MB of the wrong type, but your code can only report one of the issues. Try something like:

if(isset($_FILES['uploaded_file'])) {
    $errors     = array();
    $maxsize    = 2097152;
    $acceptable = array(
        'application/pdf',
        'image/jpeg',
        'image/jpg',
        'image/gif',
        'image/png'
    );

    if(($_FILES['uploaded_file']['size'] >= $maxsize) || ($_FILES["uploaded_file"]["size"] == 0)) {
        $errors[] = 'File too large. File must be less than 2 megabytes.';
    }

    if((!in_array($_FILES['uploaded_file']['type'], $acceptable)) && (!empty($_FILES["uploaded_file"]["type"]))) {
        $errors[] = 'Invalid file type. Only PDF, JPG, GIF and PNG types are accepted.';
    }

    if(count($errors) === 0) {
        move_uploaded_file($_FILES['uploaded_file']['tmpname'], '/store/to/location.file');
    } else {
        foreach($errors as $error) {
            echo '<script>alert("'.$error.'");</script>';
        }

        die(); //Ensure no more processing is done
    }
}

查看 move_uploaded_file()(称为移动而不是存储)了解更多信息.

Look into the docs for move_uploaded_file() (it's called move not store) for more.

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