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How can I load and display documents from a PostGRES database via SpringBoot if the type is not given when uploading?

I have a PostGreSQL database which stores documents among other things. A user can upload any document (Pdf, Word, TFFT, Excel, ...) via a form (React). Now my question is, how can I get this document now? The document is saved as binary code in the database. So I don't know the type of document. Here's what I tried:
#PostMapping(value = "/EinzelDokument/{id}")
#CrossOrigin
public void f_pp_dokument_s(HttpServletResponse response,HttpServletRequest request, #PathVariable String id)
throws IOException, URISyntaxException {
String userEntschluesselt = entschluesselUserId(request);
String aktuellerUser = request.getParameter("aktuellerUser");
Connection con = DBVerbindung();
CallableStatement properCase = null;
ResultSet rs = null;
byte[] bild = null;
if (con != null) {
try {
con.setAutoCommit(false);
properCase = con.prepareCall("SELECT * FROM ppm.f_pp_projektdokument_s(?,?)");
properCase.setInt(1, Integer.parseInt(id));
if(aktuellerUser != null)
{
properCase.setString(2, aktuellerUser);
}
else
{
properCase.setString(2, userEntschluesselt);
}
rs = properCase.executeQuery();
con.commit();
byte[] decodedBytes = null;
if (rs.next()) {
bild = rs.getBytes("projektDokument_bin");
String splitting = new String(bild, StandardCharsets.US_ASCII);
String[] s = splitting.split(",", 2);
decodedBytes = Base64.getDecoder().decode(s[1]);
} else {
//Which document type do I have to set here, or is this approach right at all?
File file = ResourceUtils.getFile("classpath:Download.pdf");
decodedBytes = Files.readAllBytes(file.toPath());
}
response.setContentType("application/octet-stream");
response.setContentLength(decodedBytes.length);
ServletOutputStream out = response.getOutputStream();
out.write(decodedBytes, 0, decodedBytes.length);
out.flush();
out.close();
} catch (SQLException e) {
Logger logger = Logger.getLogger(Logger.GLOBAL_LOGGER_NAME);
logger.setLevel(Level.ALL);
logger.warning(e.getMessage());
} finally {
if (rs != null) {
try {
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if (con != null) {
try {
con.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
if (properCase != null) {
try {
properCase.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
}
I use SpringBoot in the backend and React in the frontend.

Best case: Alter the database to add columns where you store metadata such as the kind and version of format.
Worst case: Retrieve the document, then successively decode the data into each kind of expected document. Examine the first part of the data to find expected parts, or try using utility libraries or apps to open the data as a file while trapping for exceptions/errors.

Why isn't RandomAccessFile.seek(0); moving the pointer back to the start of the file?

I'm trying to use the RandomAccessFile class to read and write information from a .json file that I pulled from a URL to an internal file for an android app, but I'm having some trouble. I've made sure that I put url.oponConnection(); in an AsyncTask so it doesn't have to run on the main activity, and I have verified that the information is being read from the .json file. (I have it output each line to my logcat).
Now my problem is that I can't read the file I created, because the pointer for the RandomAccessFile isn't being moved to the start of the file even after I've used RandomAccessFile.seek(0) I would like to make this file a .txt file if possible. I know this is a lot of code to read, but I have looked everywhere and I can't figure it out. Any help is appreciated.
AsyncTask
public class AsyncTaskActivity extends Activity {
public static class AsyncInfo extends AsyncTask<Void, Void, String>
{
protected void onPostExecute() {
}
#Override
protected void onPreExecute() {
}
#Override
protected String doInBackground(Void... params) {
try {
Log.i("AsyncTask", "Loading...");
// Make a URL to the web page
URL url = new URL("http://api.wunderground.com/api/0c0fcc3bf62ab910/conditions/q/IN/Fort_Wayne.json");
// Get the input stream through URL Connection
URLConnection con = url.openConnection();
InputStream is = con.getInputStream();
BufferedReader br = new BufferedReader(new InputStreamReader(is));
String line;
// read each line and write to text file
while ((line = br.readLine()) != null) {
Log.i("AsyncTask", line);
TextEditor.file = new File(MainActivity.path, "siteInfo.txt");
TextEditor.writeString(line);
}
TextEditor.saveAndClose();
} catch (IOException e) {
e.printStackTrace();
}
Log.i("AsyncTask", "DONE");
return "Executed";
}
}
}
TestEditor class here is where I am trying to read and write the file
public class TextEditor {
public static File file;
private static RandomAccessFile in;
private static RandomAccessFile out;
private static String s;
/**
* Opens a file to be used for input (if not already open),
* reads a line from the file, and returns the entire line of data.
*
* #return a line of text from the input file
*/
public static String readString() {
if (in == null) {
try {
in = new RandomAccessFile(file, "rw");//new BufferedReader(new FileReader(file));
in.seek(0);
s = in.readLine();
Log.e("readString", "STRING S: " + s + ".");
return s;
} catch (Exception e) {
System.err.println("Cannot open file for input!");
e.printStackTrace();
}
}
return s;
}
/**
* Opens a file to be used for output (if not already open),
* writes a string to the file and wrties a newline.
*
* #param s The string text to be written. Follwing the string, a newline is added to the file.
*/
public static void writeString(String s) {
try {
out = new RandomAccessFile(file, "rw");
out.seek(0);
out.write(s.getBytes());
}
catch (IOException e) {
e.printStackTrace();
Log.e("writeString", "File Writer Failure");
}
}
/**
* Saves and closes the file (when opened for either input or output).
* <p/>
* Note: If the program terminates before the file is closed,
* no data will be saved or written to the file.
*/
public static void saveAndClose() {
if (in != null) {
try {
in.close();
in = null;
} catch (Exception e) {
System.err.println("Cannot close input file!");
e.printStackTrace();
}
}
if (out != null) {
try {
out.close();
out = null;
} catch (Exception e) {
System.err.println("Cannot close output file!");
e.printStackTrace();
}
}
}
This is the .json file
{
"response": {
"version":"0.1",
"termsofService":"http://www.wunderground.com/weather/api/d/terms.html",
"features": {
"conditions": 1
}
}
, "current_observation": {
"image": {
"url":"http://icons.wxug.com/graphics/wu2/logo_130x80.png",
"title":"Weather Underground",
"link":"http://www.wunderground.com"
},
"display_location": {
"full":"Fort Wayne, IN",
"city":"Fort Wayne",
"state":"IN",
"state_name":"Indiana",
"country":"US",
"country_iso3166":"US",
"zip":"46801",
"magic":"1",
"wmo":"99999",
"latitude":"41.13000107",
"longitude":"-85.12999725",
"elevation":"242.9"
},
"observation_location": {
"full":"Ludwig Park, Fort Wayne, Indiana",
"city":"Ludwig Park, Fort Wayne",
"state":"Indiana",
"country":"US",
"country_iso3166":"US",
"latitude":"41.135193",
"longitude":"-85.150581",
"elevation":"774 ft"
},
"estimated": {
},
"station_id":"KINFORTW73",
"observation_time":"Last Updated on December 14, 10:34 PM EST",
"observation_time_rfc822":"Wed, 14 Dec 2016 22:34:42 -0500",
"observation_epoch":"1481772882",
"local_time_rfc822":"Wed, 14 Dec 2016 22:34:50 -0500",
"local_epoch":"1481772890",
"local_tz_short":"EST",
"local_tz_long":"America/New_York",
"local_tz_offset":"-0500",
"weather":"Partly Cloudy",
"temperature_string":"11.3 F (-11.5 C)",
"temp_f":11.3,
"temp_c":-11.5,
"relative_humidity":"44%",
"wind_string":"From the WSW at 4.9 MPH Gusting to 7.4 MPH",
"wind_dir":"WSW",
"wind_degrees":243,
"wind_mph":4.9,
"wind_gust_mph":"7.4",
"wind_kph":7.9,
"wind_gust_kph":"11.9",
"pressure_mb":"1022",
"pressure_in":"30.17",
"pressure_trend":"+",
"dewpoint_string":"-6 F (-21 C)",
"dewpoint_f":-6,
"dewpoint_c":-21,
"heat_index_string":"NA",
"heat_index_f":"NA",
"heat_index_c":"NA",
"windchill_string":"3 F (-16 C)",
"windchill_f":"3",
"windchill_c":"-16",
"feelslike_string":"3 F (-16 C)",
"feelslike_f":"3",
"feelslike_c":"-16",
"visibility_mi":"10.0",
"visibility_km":"16.1",
"solarradiation":"0",
"UV":"0.0","precip_1hr_string":"0.00 in ( 0 mm)",
"precip_1hr_in":"0.00",
"precip_1hr_metric":" 0",
"precip_today_string":"0.00 in (0 mm)",
"precip_today_in":"0.00",
"precip_today_metric":"0",
"icon":"partlycloudy",
"icon_url":"http://icons.wxug.com/i/c/k/nt_partlycloudy.gif",
"forecast_url":"http://www.wunderground.com/US/IN/Fort_Wayne.html",
"history_url":"http://www.wunderground.com/weatherstation/WXDailyHistory.asp?ID=KINFORTW73",
"ob_url":"http://www.wunderground.com/cgi-bin/findweather/getForecast?query=41.135193,-85.150581",
"nowcast":""
}
}

So I figured out how to read/write the data as a string using a Scanner and a BufferedWriter. Here is the edited TextEditor class.
public class TextEditor {
public static File file;
private static Scanner in;
private static BufferedWriter out;
/**
* Opens a file to be used for input (if not already open),
* reads a line from the file, and returns the entire line of data.
*
* #return a line of text from the input file
*/
public static String readString() {
if (in == null) {
try {
in = new Scanner(file);
} catch (Exception e) {
System.err.println("Cannot open file for input!");
e.printStackTrace();
}
}
try {
if (in.hasNext()) {
String s = in.nextLine();
return s;
} else {
return null;
}
} catch (Exception e) {
System.err.println("Cannot read file!");
e.printStackTrace();
}
return null;
}
/**
* Opens a file to be used for output (if not already open),
* writes a string to the file and writes a newline.
*
* #param s The string text to be written. Following the string, a newline is added to the file.
*/
public static void writeString(String s) {
if (out == null) {
try {
out = new BufferedWriter(new FileWriter(file));
}
catch (Exception e) {
System.err.println("Cannot create file for output!");
e.printStackTrace();
}
}
try {
out.write(s);
out.newLine();
}
catch (Exception e) {
System.err.println("Cannot write file!");
e.printStackTrace();
}
}
/**
* Saves and closes the file (when opened for either input or output).
* <p/>
* Note: If the program terminates before the file is closed,
* no data will be saved or written to the file.
*/
public static void saveAndClose() {
if (in != null) {
try {
in.close();
in = null;
}
catch (Exception e) {
System.err.println("Cannot close input file!");
e.printStackTrace();
}
}
if (out != null) {
try {
out.close();
out = null;
}
catch (Exception e) {
System.err.println("Cannot close output file!");
e.printStackTrace();
}
}
}
}

save a created propertyfile in specific folder

How can I save a prop file in a specific folder for example,
now it is saved in the root I guess, but it needs to be in the same folder as the class where it is created.
I also want to know how to load it. If it possible to load a properties file easily from the root then it is okay as well to save it in the root.
code creating the file, first 2 lines with // ( = make code work now without using prop file), class name = Providers
public static DataAccessProvider createProvider (URL url) {
//MovieDAOOnline mdaoOn = new MovieDAOOnline();
//mdaoOn.setUrl(url);
Properties prop = new Properties();
OutputStream output = null;
try {
output = new FileOutputStream("config.properties");
// set the properties value
prop.setProperty("uri", url.toString());
prop.store(output, null);
} catch (IOException io) {
io.printStackTrace();
} finally {
if (output != null) {
try {
output.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return new OnlineProvider();
}
code for getting the file, first line in comment needs to be changed to get uri from propertie:
public Movie getMovie(int id) throws DataAccessException{
//StringBuilder builder = new StringBuilder(url.toString());
builder.append("movies.xml");
MovieConfigRead mcr = new MovieConfigRead();
List<Movie> film = null;
try {
film = mcr.geefMovies(builder.toString());
} catch (JAXBException e) {
throw new DataAccessException();
} catch (MalformedURLException e) {
throw new DataAccessException();
}
for (Movie movie : film) {
if (movie.getId() == id) {
return movie;
}
}
return null;
}

Android Database Not Always Getting Deleted On Uninstall/Install

when i try to uninstall my android app and reinstall it again to get the new updated database, the database sometimes does not get updated, i don't know why.
Database gets updated after trying a random number of attempts of install/uninstall,
Can someone help me with this problem.
What I tried is:
when uninstalling, first I force stop the application, then I cleared the data and then uninstalled.
here is the code that is executed in the MainActivity when the app starts.
try {
File dbFile = getDatabasePath("MyDatabase.db");
if (!dbFile.exists()) {
Log.d(TAG, "Datbase does not exist");
this.copy("MY.db",dbFile.getAbsolutePath());
}
}
catch (Exception e) {
Log.e(TAG, "Error in Copying: "+e.toString());
try {
AppLogging(TAG, "Error in copying Database:" + e.toString());
}
catch(Exception l) {
}
}
Copy method
private void copy(String file, String folder) throws IOException {
try {
File CheckDirectory;
CheckDirectory = new File(folder);
String parentPath = CheckDirectory.getParent();
File filedir = new File(parentPath);
if (!filedir.exists()) {
if (!filedir.mkdirs()) {
return;
}
}
InputStream in = this.getApplicationContext().getAssets().open(file);
File newfile = new File(folder);
OutputStream out = new FileOutputStream(newfile);
byte[] buf = new byte[1024];
int len;
while ((len = in.read(buf)) > 0) {
out.write(buf, 0, len);
}
in.close();
out.close();
}
catch (Exception e) {
Log.e(TAG, "Error in Copy: "+e.toString());
try {
AppLogging(TAG, "ERROR In Copy Method (Database) " + e.toString());
}
catch(Exception l) {
}
}
}

Java - passing input into external C/C++ application

I'm trying to enter some value in external application using Java.
Java application looks like this:
Runtime runtime = Runtime.getRuntime();
// ... str build ...
proc = runtime.exec(str);
BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(proc.getOutputStream()));
bw.write(value);
bw.flush();
bw.close();
if (proc.waitFor() != 0)
// error msg
// the end
Application hangs at waitFor method.
External application looks like this:
welcome banner
please enter 8 character input:
Welcome banner is printed using printf and input is taken with SetConsoleMode/ReadConsoleInput. ReadConsoleInput reads one char and they are masked with * character.
Help

you can use:
proc.getOutputStream().write("some date".getBytes())
keep in mind that you HAVE to read everything the app send to stdout and stderr, else it might get stuck writing there.
I use a generic class to read it in a different thread.
usage is like:
InputStreamSucker inSucker = new InputStreamSucker(proc.getInputStream());
InputStreamSucker errSucker = new InputStreamSucker(proc.getErrorStream());
proc.waitFor();
int exit = process.exitValue();
inSucker.join();
errSucker.join();
InputStreamSucker code is here:
public class InputStreamSucker extends Thread
{
static Logger logger = Logger.getLogger(InputStreamSucker.class);
private final BufferedInputStream m_in;
private final ByteArrayOutputStream m_out;
private final File m_outFile;
public InputStreamSucker(InputStream in) throws FileNotFoundException
{
this(in, null);
}
public InputStreamSucker(InputStream in, File outFile) throws FileNotFoundException
{
m_in = new BufferedInputStream(in, 4096);
m_outFile = outFile;
m_out = new ByteArrayOutputStream();
start();
}
#Override
public void run()
{
try
{
int c;
while ((c = m_in.read()) != -1)
{
m_out.write(c);
}
}
catch (IOException e)
{
logger.error("Error pumping stream", e);
}
finally
{
if (m_in != null)
{
try
{
m_in.close();
}
catch (IOException e)
{
}
}
try
{
m_out.close();
}
catch (IOException e)
{
logger.error("Error closing out stream", e);
}
if (m_outFile != null)
{
byte data[] = m_out.toByteArray();
if (data.length > 0)
{
FileOutputStream fo = null;
try
{
fo = new FileOutputStream(m_outFile);
fo.write(data);
}
catch (IOException e)
{
logger.error("Error writing " + m_outFile);
}
finally
{
try
{
if (fo != null) fo.close();
}
catch (IOException e)
{
logger.error("Error closing " + m_outFile);
}
}
}
}
}
}
public String getOutput()
{
return new String(m_out.toByteArray());
}
}

Got the answer! The trick is to use WriteConsoleInput() API because program expects keyboard event, not text ... That's why the waitFor() waited forever! :)