java 获取ftp文件列表以及模糊查询，并对结果进行分页

/**
     * 获取ftp文件列表
     * ".*\\.txt" ：匹配所有以".txt" 结尾的文件名。其中，星号（*）表示任意字符序列，反斜杠（\）用于转义点号（.）字符。
     * ".*" + "任意字符" + ".*\\.txt" ：匹配所有包含 "表示匹配任意多个任意字符"和以".txt" 结尾的文件名。其中，星号（*）表示任意字符序列，反斜杠（\）用于转义点号（.）字符。
     * @param params
     * @return
     */
    @PostMapping("/getFTPFileList")
    @ResponseBody
    public Result getFTPFileList(@RequestBody Map<String,Object> params) {
        FTPClient ftpClient = new FTPClient();
        List<Map<String, Object>> list = new ArrayList<>();
        FTPFile[] page = new FTPFile[0];
        int pageNum = ("".equals(String.valueOf(params.get("pageNo"))) || params.get("pageNo") == null) ? 1 : Integer.valueOf(String.valueOf(params.get("pageNo")));
        int pageSize = ("".equals(String.valueOf(params.get("pageSize"))) || params.get("pageSize") == null) ? 20 : Integer.valueOf(String.valueOf(params.get("pageSize")));
        int start = (pageNum - 1) * pageSize;
        int end = start + pageSize - 1;
        try {
            System.out.println("开始连接ftp");
            ftpClient.connect(host, port);
            ftpClient.login(username, password);
//            ftpClient.connect(ip, pr);
//            ftpClient.login(user, pass);
            int reply = ftpClient.getReplyCode();
            if (!FTPReply.isPositiveCompletion(reply)) {
                ftpClient.disconnect();
                return Result.error("ftp连接失败：" + reply);
            }else{
                System.out.println("ftp连接成功：" + reply);
            }
            ftpClient.enterLocalPassiveMode(); //被动模式
            String p = ("".equals(String.valueOf(params.get("path"))) || params.get("path") == null) ? path : String.valueOf(params.get("path"));
            String f = ("".equals(String.valueOf(params.get("file"))) || params.get("file") == null) ? file : ".*" + String.valueOf(params.get("file")).replaceAll("_","") + ".*";
            System.out.println("正则匹配：" + f);
            FTPFile[] files = ftpClient.listFiles(p);
            //根据名称进行正则匹配文件
            Pattern filePattern = Pattern.compile(f);
            if (files == null || files.length < start) {
                return Result.success(new FTPFile[0]);
            }
            int count = Math.min(end + 1, files.length) - start;
            page = new FTPFile[count];
            //对结果进行分页
            System.arraycopy(files, start, page, 0, count);
            for (FTPFile file : page) {
                if (file.isFile() && filePattern.matcher(file.getName()).matches()) {
                    Map<String, Object> map = new HashMap<>();
                    map.put("name", file.getName());
                    //计算大小MB
                    double megabytes = (double) file.getSize() / 1048576;
                    if (megabytes >= 1024) {
                        //计算大小G
                        megabytes = megabytes / 1024;
                        String formattedNumber = String.format("%.1f", megabytes);
                        map.put("size", formattedNumber + "G");
                    } else {
                        String formattedNumber = String.format("%.1f", megabytes);
                        map.put("size", formattedNumber + "MB");
                    }
                    list.add(map);
                }
            }
        } catch (IOException e) {
            throw new RuntimeException(e);
        } finally {
            try {
                ftpClient.logout();
                ftpClient.disconnect();
                System.out.println("已关闭ftp链接");
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return Result.success(list);
    

{
    "path":"/visit",
    "file":"202305",
    "pageNum": 1,
    "pageSize": 20
}