PHP实现文件上传与下载的示例代码

//index.html 
<form action="./server.php" enctype="multipart/form-data" method="post">
        <label>
            <input type="file" name="files" value="" >
        </label>
        <button type="submit">提交</button>
 </form>
     
 //server.php
   print_r($_FILES); 

/*

Array
(
    [files] => Array
        (
            [name] => Key.txt
            [full_path] => Key.txt
            [type] => text/plain
            [tmp_name] => C:\wamp64\tmp\php665C.tmp
            [error] => 0
            [size] => 54
        )

)

*/

<?php
if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    // 检查文件是否成功上传
    if (isset($_FILES['file_name']) && $_FILES['file_name']['error'] === UPLOAD_ERR_OK) {
        // 文件上传成功
        $tempFilePath = $_FILES['file_name']['tmp_name'];
        $fileName = $_FILES['file_name']['name'];

        // 执行进一步的处理操作
        // ...

        echo "文件上传成功！";
    } else {
        // 文件上传失败或未选择文件
        echo "文件上传失败！";
    }
}
?>

<form action="./server.php" method="post" enctype="multipart/form-data">
        <input type="file" name="image">
        <input type="file" name="image[]">
        <input type="file" name="image[]">
        <button class="btn">提交</button>
</form>

if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    // 检查是否有文件上传
    if (isset($_FILES['images'])) {
        $fileCount = count($_FILES['images']['name']);
        
        // 遍历每个上传的文件
        for ($i = 0; $i < $fileCount; $i++) {
            // 检查文件是否成功上传
            if ($_FILES['images']['error'][$i] === UPLOAD_ERR_OK) {
                $tempFilePath = $_FILES['images']['tmp_name'][$i];
                $fileName = $_FILES['images']['name'][$i];

                // 执行进一步的处理操作
                // ...

                echo "文件 $fileName 上传成功！<br>";
            } else {
                // 文件上传失败或未选择文件
                echo "文件上传失败！<br>";
            }
        }
    } else {
        // 没有文件被上传
        echo "没有文件被上传！<br>";
    }
}

$file = "dog.jpg";
$fileName = basename($file);
header("Content-type: application/octet-stream");
header("Content-Disposition: attachment; filename={$fileName}");
header("Accept-ranges: bytes");
header("Content-Length: " . filesize($file));
readfile($file);