Java从服务器端下载文件保存到本地，不是下载的图片？

Question

public static void downloadFile(String urlPath, String filePath) throws IOException {

        URL url = new URL(urlPath);

        String name = urlPath.substring(urlPath.lastIndexOf("=")+1);

        String filePaths = filePath+"/"+name;

        File dirFile = new File(filePath);

        if (!dirFile.exists()) {

            dirFile.mkdir();

        }

        URLConnection connection = url.openConnection();

        InputStream in = connection.getInputStream();

        FileOutputStream os = new FileOutputStream(filePaths);

        byte[] buffer = new byte[4 * 1024];

        int read;

        while ((read = in.read(buffer)) > 0) {

            os.write(buffer, 0, read);

        }

        os.close();

        in.close();

    }

    public static void main(String[] args) {

        String urlPath = "http://10.192.32.111:80/production-jcw/getDownload.do?fileName=49e23d3a-5e11-432d-9f33-91c93130b37b.dwg";

        String filePath = "C:/Users/MrLi/Desktop/";

        try {

            downloadFile(urlPath, filePath);

            System.out.println("下载成功");

        } catch (IOException e) {

            e.printStackTrace();

            System.out.println("下载失败");

        }

    }