Php 如果服务器中是否存在文件，则显示和隐藏按钮（href=）

我试图编辑一个类似的解决方案，但它没有达到预期的效果。我不确定我的编码可能我错了，我使用的是html。是否有一种方法可以隐藏按钮（href=），如果文件存在，则显示是否未找到？谢谢大家!

参考：

然后

然后

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另一种方法是向用户提供现有文件的列表，并允许用户从列表中进行选择

<?php
// Initialize an empty array
$files = [];

// Get all the files in a directory (this will also return directories)
foreach (glob('*') as $f) {

        // If the item is a file, add it to the files array
        if (is_file($f)) {
                $files[] = $f;
        }
}
?>

<!-- Create a select statement with the files that exist -->
<select id="files">
<!-- Placeholder -->
<option disabled selected>Select file</option>

<!-- Loop through all the files and create options for them -->
<?php foreach ($files as $f) : ?>
<option><?= $f ?></option>
<?php endforeach ?>
</select>

<!-- The button would run the download using the selected file as the source (additional JavaScript required) -->
<button id="go">Download</button>

选择文件
下载

另一种方法是向用户提供现有文件的列表，并允许用户从列表中进行选择

<?php
// Initialize an empty array
$files = [];

// Get all the files in a directory (this will also return directories)
foreach (glob('*') as $f) {

        // If the item is a file, add it to the files array
        if (is_file($f)) {
                $files[] = $f;
        }
}
?>

<!-- Create a select statement with the files that exist -->
<select id="files">
<!-- Placeholder -->
<option disabled selected>Select file</option>

<!-- Loop through all the files and create options for them -->
<?php foreach ($files as $f) : ?>
<option><?= $f ?></option>
<?php endforeach ?>
</select>

<!-- The button would run the download using the selected file as the source (additional JavaScript required) -->
<button id="go">Download</button>

选择文件
下载

哇，太棒了！我将尝试并学习如何实现这一点。非常感谢你！哇，太棒了！我将尝试并学习如何实现这一点。非常感谢你！

<script
              src="https://code.jquery.com/jquery-3.3.1.min.js"
              integrity="sha256-FgpCb/KJQlLNfOu91ta32o/NMZxltwRo8QtmkMRdAu8="
              crossorigin="anonymous">

</script>

.hidden {
display: none
}

<button type="button" class="hidden" id="test_btn">Download</button>

<script>
$(document).ready(function () {
                $.ajax({
                url: '/path/to/file_checker.php',
                type: 'GET',
                success:function(data){
                var obj = jQuery.parseJSON(data);
                           if(obj.callback == 1) {
                             $('button#test_btn').removeClass('hidden');
                            }
                }
                });
});
</script>

if (file_exists("/aaa/file.txt")) {
    $data = array('callback' => 1);
    echo json_encode($data);
}
else {
    $data = array('callback' => 0);
    echo json_encode($data);
}

<?php
// Initialize an empty array
$files = [];

// Get all the files in a directory (this will also return directories)
foreach (glob('*') as $f) {

        // If the item is a file, add it to the files array
        if (is_file($f)) {
                $files[] = $f;
        }
}
?>

<!-- Create a select statement with the files that exist -->
<select id="files">
<!-- Placeholder -->
<option disabled selected>Select file</option>

<!-- Loop through all the files and create options for them -->
<?php foreach ($files as $f) : ?>
<option><?= $f ?></option>
<?php endforeach ?>
</select>

<!-- The button would run the download using the selected file as the source (additional JavaScript required) -->
<button id="go">Download</button>