Javascript 使用AJAX检查（下载）文件是否存在&；PHP

我有一个下载页面，访问者可以在输入字段中输入ZIP文件的名称（不带扩展名）

index.php:

<form action="download-script.php" method="post">
    <input type="text" name="file" placeholder="Enter filename here" />
    <input type="submit" value="Download starten" />
</form>

<?php

$file = preg_replace("/[^0-9a-z.\-_ ]/i", "", $_POST['file']);
$file = 'download/' . $file . '.zip';

if (file_exists($file)) {
    header('Content-Disposition: attachement; filename=' . basename($file));
    header('Content-Type: application/force-download');
    header('Expires: 0');
    header('Cache-Control: must-revalidate');
    header('Content-Length: ' . filesize($file));
    header('Connection: close');
    readfile($file);
} 
else {
    echo "File not found";
    exit;
}
?>

ZIP文件存储在单独的文件夹“files”中。如果访问者知道文件的名称，一切都很好。如果文件名拼写错误或为空，脚本将显示一条错误消息：

download-script.php:

<form action="download-script.php" method="post">
    <input type="text" name="file" placeholder="Enter filename here" />
    <input type="submit" value="Download starten" />
</form>

<?php

$file = preg_replace("/[^0-9a-z.\-_ ]/i", "", $_POST['file']);
$file = 'download/' . $file . '.zip';

if (file_exists($file)) {
    header('Content-Disposition: attachement; filename=' . basename($file));
    header('Content-Type: application/force-download');
    header('Expires: 0');
    header('Cache-Control: must-revalidate');
    header('Content-Length: ' . filesize($file));
    header('Connection: close');
    readfile($file);
} 
else {
    echo "File not found";
    exit;
}
?>

---

我的目标是在

index.php

上显示错误消息，而不是在

下载脚本.php

上显示错误消息，因为

下载脚本.php

只会显示错误消息。

您可以这样做，如果有帮助，请告诉我

index.php

<?php

if (isset($_POST['submit_form'])) {

    $file = preg_replace("/[^0-9a-z.\-_ ]/i", "", $_POST['file']);
    $file_path =  'download/'. $file . '.zip';

    if (file_exists($file_path)) {

        echo "<script>window.location.href='download-script.php?file=".$file."'</script>";
    }
    else { echo "File not found"; exit; }
} 
?>

<form action="" method="post">
    <input type="text" name="file" placeholder="Enter filename here" />
    <input type="submit" name="submit_form" value="Download starten" />
</form>

<?php

$file = 'download/'. $_GET['file'] . '.zip';

if (file_exists($file)) {
    header('Content-Disposition: attachement; filename=' . basename($file));
    header('Content-Type: application/force-download');
    header('Expires: 0');
    header('Cache-Control: must-revalidate');
    header('Content-Length: ' . filesize($file));
    header('Connection: close');
    readfile($file);
}

<?php

if (isset($_POST['submit_form'])) {

    $file = preg_replace("/[^0-9a-z.\-_ ]/i", "", $_POST['file']);
    $file_path =  'download/'. $file . '.zip';

    if (file_exists($file_path)) {

        header('Content-Disposition: attachement; filename=' . basename($file_path));
        header('Content-Type: application/force-download');
        header('Expires: 0');
        header('Cache-Control: must-revalidate');
        header('Content-Length: ' . filesize($file));
        header('Connection: close');
        readfile($file);
    }
    else { echo "File not found"; exit; }
} 
?>

<form action="" method="post">
    <input type="text" name="file" placeholder="Enter filename here" />
    <input type="submit" name="submit_form" value="Download starten" />
</form>

<?php
if (isset($_REQUEST["error"])) {
    echo "File not found";
}
?>
<form action="download-script.php" method="post">
<input type="text" name="file" placeholder="Enter filename here" />
<input type="submit" value="Download starten" />
</form>

<?php
$file = preg_replace("/[^0-9a-z.\-_ ]/i", "", $_POST['file']);
$file = 'download/' . $file . '.zip';

if (file_exists($file)) {
    header('Content-Disposition: attachement; filename=' . basename($file));
    header('Content-Type: application/force-download');
    header('Expires: 0');
    header('Cache-Control: must-revalidate');
    header('Content-Length: ' . filesize($file));
    header('Connection: close');
    readfile($file);
} 
else {
    header('Location: index.php?error=1');
    exit;
}
?>

---

在index.php中

<?php

if (isset($_POST['submit_form'])) {

    $file = preg_replace("/[^0-9a-z.\-_ ]/i", "", $_POST['file']);
    $file_path =  'download/'. $file . '.zip';

    if (file_exists($file_path)) {

        echo "<script>window.location.href='download-script.php?file=".$file."'</script>";
    }
    else { echo "File not found"; exit; }
} 
?>

<form action="" method="post">
    <input type="text" name="file" placeholder="Enter filename here" />
    <input type="submit" name="submit_form" value="Download starten" />
</form>

<?php

$file = 'download/'. $_GET['file'] . '.zip';

if (file_exists($file)) {
    header('Content-Disposition: attachement; filename=' . basename($file));
    header('Content-Type: application/force-download');
    header('Expires: 0');
    header('Cache-Control: must-revalidate');
    header('Content-Length: ' . filesize($file));
    header('Connection: close');
    readfile($file);
}

<?php

if (isset($_POST['submit_form'])) {

    $file = preg_replace("/[^0-9a-z.\-_ ]/i", "", $_POST['file']);
    $file_path =  'download/'. $file . '.zip';

    if (file_exists($file_path)) {

        header('Content-Disposition: attachement; filename=' . basename($file_path));
        header('Content-Type: application/force-download');
        header('Expires: 0');
        header('Cache-Control: must-revalidate');
        header('Content-Length: ' . filesize($file));
        header('Connection: close');
        readfile($file);
    }
    else { echo "File not found"; exit; }
} 
?>

<form action="" method="post">
    <input type="text" name="file" placeholder="Enter filename here" />
    <input type="submit" name="submit_form" value="Download starten" />
</form>

<?php
if (isset($_REQUEST["error"])) {
    echo "File not found";
}
?>
<form action="download-script.php" method="post">
<input type="text" name="file" placeholder="Enter filename here" />
<input type="submit" value="Download starten" />
</form>

<?php
$file = preg_replace("/[^0-9a-z.\-_ ]/i", "", $_POST['file']);
$file = 'download/' . $file . '.zip';

if (file_exists($file)) {
    header('Content-Disposition: attachement; filename=' . basename($file));
    header('Content-Type: application/force-download');
    header('Expires: 0');
    header('Cache-Control: must-revalidate');
    header('Content-Length: ' . filesize($file));
    header('Connection: close');
    readfile($file);
} 
else {
    header('Location: index.php?error=1');
    exit;
}
?>

在下载script.php

<?php

if (isset($_POST['submit_form'])) {

    $file = preg_replace("/[^0-9a-z.\-_ ]/i", "", $_POST['file']);
    $file_path =  'download/'. $file . '.zip';

    if (file_exists($file_path)) {

        echo "<script>window.location.href='download-script.php?file=".$file."'</script>";
    }
    else { echo "File not found"; exit; }
} 
?>

<form action="" method="post">
    <input type="text" name="file" placeholder="Enter filename here" />
    <input type="submit" name="submit_form" value="Download starten" />
</form>

<?php

$file = 'download/'. $_GET['file'] . '.zip';

if (file_exists($file)) {
    header('Content-Disposition: attachement; filename=' . basename($file));
    header('Content-Type: application/force-download');
    header('Expires: 0');
    header('Cache-Control: must-revalidate');
    header('Content-Length: ' . filesize($file));
    header('Connection: close');
    readfile($file);
}

<?php

if (isset($_POST['submit_form'])) {

    $file = preg_replace("/[^0-9a-z.\-_ ]/i", "", $_POST['file']);
    $file_path =  'download/'. $file . '.zip';

    if (file_exists($file_path)) {

        header('Content-Disposition: attachement; filename=' . basename($file_path));
        header('Content-Type: application/force-download');
        header('Expires: 0');
        header('Cache-Control: must-revalidate');
        header('Content-Length: ' . filesize($file));
        header('Connection: close');
        readfile($file);
    }
    else { echo "File not found"; exit; }
} 
?>

<form action="" method="post">
    <input type="text" name="file" placeholder="Enter filename here" />
    <input type="submit" name="submit_form" value="Download starten" />
</form>

<?php
if (isset($_REQUEST["error"])) {
    echo "File not found";
}
?>
<form action="download-script.php" method="post">
<input type="text" name="file" placeholder="Enter filename here" />
<input type="submit" value="Download starten" />
</form>

<?php
$file = preg_replace("/[^0-9a-z.\-_ ]/i", "", $_POST['file']);
$file = 'download/' . $file . '.zip';

if (file_exists($file)) {
    header('Content-Disposition: attachement; filename=' . basename($file));
    header('Content-Type: application/force-download');
    header('Expires: 0');
    header('Cache-Control: must-revalidate');
    header('Content-Length: ' . filesize($file));
    header('Connection: close');
    readfile($file);
} 
else {
    header('Location: index.php?error=1');
    exit;
}
?>

您可以尝试ajax，但它更复杂，更难调试，请参见

---

或者举个例子。

嗨，施里坎特·马夫兰卡！谢谢你的支持！错误消息工作正常！但是下载脚本不再工作了。JavaScript

window.location.href='download-script.php？file=“.$file.”有问题。

。脚本通常在后台工作。现在javascript将加载/显示download-script.php，而不是加载文件。此链接出现在浏览器中：…/download script.php？file=download/testfile.zip，不会加载任何文件…我的答案中做了一些更改，请检查并让我知道：）嗨，Shrikant！我仍然有相同的问题：

window.location.href='download-script.php？file=“.$file.”

将加载/显示脚本（空白页），但不加载文件：-（修改了

download script.php

；添加了缺少的

.zip

扩展名。请现在检查，它应该可以工作了。非常好，谢谢！但现在我们遇到了一个新问题：按下下载按钮后，表单（表单，页脚）消失后开始的页面内容。这是生成的源代码：

[…]window.location.href='download-script.php？file=test'

您好，谢谢您的脚本！您的解决方案运行良好：-）