PHP文件的上传和下载示例

<!-- 文件上传表单 -->
<form action="upload.php" method="post" enctype="multipart/form-data">
  <input type="file" name="file">
  <input type="submit" value="Upload">
</form>

<!-- 文件下载链接 -->
<a href="download.php?file=example.pdf">Download example.pdf</a>

// upload.php - 文件上传处理
if ($_FILES['file']['error'] == UPLOAD_ERR_OK) {
  $name = $_FILES['file']['name'];
  $tmp_name = $_FILES['file']['tmp_name'];
  move_uploaded_file($tmp_name, "uploads/$name");
  echo "File uploaded successfully.";
} else {
  echo "File upload failed.";
}

// download.php - 文件下载处理
$file = $_GET['file'];
if (isset($file)) {
  $path = "uploads/$file";
  if (file_exists($path)) {
    header('Content-Type: application/octet-stream');
    header('Content-Disposition: attachment; filename=' . basename($path));
    header('Content-Length: ' . filesize($path));
    readfile($path);
    exit;
  } else {
    echo "File not found.";
  }
}