2

I want to check for a version changed/get metadata of a text-file with a shared link on dropbox. I will not be using dropbox api as it makes users use their own accounts. I want them to link to my account and I cannot do that manually since I might change my password later.

so: no auth token, just get metadata from shared link of dropbox so that I can check for version changes and if the version has changed download the contents of the new file.

also: I'm open to other suggestions to make this work as well. Please explain in a little detail your solution.

Updated E-Tag Issue:

public void getFromOnlineTxtDatabase(){
        try{
            URL url = new URL("url-here");
            HttpURLConnection.setFollowRedirects(true);
            HttpURLConnection con = (HttpURLConnection) url.openConnection();
            con.setDoOutput(false);
            con.setReadTimeout(20000);
            con.setRequestProperty("Connection", "keep-alive");
            //get etag for update check
                String etag = con.getHeaderField("etag");
            //String etag= "";

            con.setRequestProperty("User-Agent", "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:16.0) Gecko/20100101 Firefox/16.0");
            ((HttpURLConnection) con).setRequestMethod("GET");
            //System.out.println(con.getContentLength()) ;
            con.setConnectTimeout(5000);
            BufferedInputStream in = new BufferedInputStream(con.getInputStream());
            int responseCode = con.getResponseCode();
            if (responseCode == HttpURLConnection.HTTP_OK) {
                System.out.println(responseCode);
            }
            StringBuffer buffer = new StringBuffer();
            int chars_read;
            //int total = 0;
            while ((chars_read = in.read()) != -1) 
            {
                char g = (char) chars_read;
                buffer.append(g);
            }
            final String page = buffer.toString();
            //create password_ems.txt to internal
            if (fileExistance("data.txt")){
                File dir = getFilesDir();
                File file = new File(dir, "data.txt");
                boolean deleted = file.delete();
                stringToTxt(page, "data.txt");


            }else{
                stringToTxt(page, "data.txt");
            }

            if (fileExistance("data_etag.txt")){
                File dir = getFilesDir();
                File file = new File(dir, "etag.txt");
                boolean deleted = file.delete();
                stringToTxt(etag, "etag.txt");


            }else{
                //create etag_file
                stringToTxt(etag, "data_etag.txt");
            }

            //  Log.i("Page", page);
        }catch(Exception e){
            showDialog("Database Fetch Failure","Unable to Fetch Password Database, check your internet" +
                    " connection and try again later.",0);
            Log.i("Page", "Error");
        }

    }
4

1 回答 1

3

如果您针对公共或共享的 Dropbox URL 执行 HTTPHEAD请求，您将获得一个etag标头等。我不知道这种行为是否得到保证，因为我认为它没有在任何地方记录，但至少现在etag标题可用于确定文件何时更改。（如果etag不同，则文件已更改。）

编辑

一般来说，当使用 ETags 时，最有效的做法是发出一个GET带有If-None-Match: <old etag>. 如果内容没有改变，这将响应 304，但如果内容已经改变，这将按照正常GET请求下载新内容（响应为 200）。

于 2013-09-03T16:14:41.383 回答