如何在使用HttpURLConnection（android / java）发布之前获取VIEWSTATE？

Question

I am writing an Android application, and have been looking for a way to get the _VIEWSTATE from the server I want to post to so I can put it in my Http post content. A few people recommended regex, but then some other pros were strongly opposed to parsing HTML with regex. So, how to parse the _VIEWSTATE ? I am using HttpURLConnection/HttpsURLConnection in an AsyncTask. Also, don't I need to put the InputStream reader first, to get the _VIEWSTATE first? All the android examples put the input stream after the output stream. Here is what my code looks like so far (posting to one site that has three pages that have to be "clicked through"):

In my Activity, I call the Async task like this:

//execute AsyncTask for all three reports
    submit_report.execute(report1, report2, report3); 

My Async task doInBackground method:

class UploadReportTask extends AsyncTask<HashMap<String,String>, ProgressBar, Void> {

//this is called on task.execute
    protected Void doInBackground(HashMap<String,String>...maps) {
        System.out.println("Report is being uploaded"); 

        URL url = null;
        try {
            url = new URL(getString(R.string.url_dnc));
        } catch (MalformedURLException e) {
            e.printStackTrace();
        }
        HttpURLConnection urlConnection = null;
        try {
            urlConnection = (HttpURLConnection) url.openConnection();
        } catch (IOException e) {
            e.printStackTrace();
        }

        try {
            urlConnection.setDoOutput(true);
            urlConnection.setRequestProperty("Accept-Charset", utf);
            urlConnection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded;charset=" + utf);
            urlConnection.setChunkedStreamingMode(0);


            //For each map in maps, encode the map,
            //get the headers, add the headers to the map, convert to bytes,
            //then post the bytes, 
            //get response.
            for (HashMap<String,String> map : maps){
                byte[] payload = makePayload(map);
                OutputStream out = new BufferedOutputStream(urlConnection.getOutputStream());
                //urlConn.connect //I think this happens here
                out.write(payload);

                InputStream in = new BufferedInputStream(urlConnection.getInputStream());

                BufferedReader reader = new BufferedReader(new InputStreamReader(in));
                int length = in.read();
                String result, line = reader.readLine();
                result = line;
                while (length != -1){
                    result+=line;
                }
                System.out.println(result);
                out.flush();
                out.close();
            }

        } catch (IOException e) {
            e.printStackTrace();
        }
        finally{
            urlConnection.disconnect();
        }
        return null;    
    }

Answer 1

protected String parseViewstate(String response){
        int i = 0;
        String viewstate = "";
        while (true){
            int found = response.indexOf("\"__VIEWSTATE\"", i);
            if (found == -1) break;
            int start = found + 38; //check numbers from start of "__V"
            int end  = (response.indexOf("/>", start)) -2;
            viewstate = response.substring(start, end);
            i = end + 1;    
        }return viewstate;
    }