如何在PHP中创建zip文件？

$zip = new ZipArchive();

$zipFile = 'path/to/newfile.zip';
if ($zip->open($zipFile, ZipArchive::CREATE | ZipArchive::OVERWRITE) === TRUE) {
  // 添加文件到zip文件中
  // ...
  // 关闭zip文件
  $zip->close();
  echo 'Zip文件创建成功。';
} else {
  echo '无法创建Zip文件。';
}

$zip->addFile('path/to/file1.txt', 'file1.txt'); // 添加一个文件
$zip->addFile('path/to/file2.txt', 'file2.txt'); // 添加另一个文件

function addFolderToZip($folder, &$zip, $zipPath) {
    $handle = opendir($folder);
    while (false !== ($entry = readdir($handle))) {
        if ($entry != "." && $entry != "..") {
            $filePath = $folder . "/" . $entry;
            $localPath = $zipPath . "/" . $entry;
            if (is_file($filePath)) {
                $zip->addFile($filePath, $localPath);
            } elseif (is_dir($filePath)) {
                $zip->addEmptyDir($localPath);
                addFolderToZip($filePath, $zip, $localPath);
            }
        }
    }
    closedir($handle);
}

$folder = 'path/to/folder';
$zipPath = 'folder';
addFolderToZip($folder, $zip, $zipPath);

$zip->setArchiveComment('Zip文件注释');
$zip->setCompressionIndex(9); // 设置压缩级别（0-9）