Develop Reference

Android Protected variable storage even after factory reset

I'm working on Aosp. I want to keep a variable in the system but When I use a shared preference, the variable is deleted when I perform a Factory reset. I need to change and save the variable I want to keep. Think like a Mac address

You can put all the variables you want to save into a json and save it in internal storage
and you can retrive it whenever you want
example code for read and write
private void saveConfig(String data) {
try {
OutputStreamWriter outputStreamWriter = new OutputStreamWriter(openFileOutput("config.txt", Context.MODE_PRIVATE));
outputStreamWriter.write(data);
outputStreamWriter.close();
}
catch (IOException e) {
Log.e("Exception", "File write failed: " + e.toString());
} }
private String readConfig() {
String data = "";
try {
InputStream inputStream = context.openFileInput("config.txt");
if ( inputStream != null ) {
InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
String receiveString = "";
StringBuilder stringBuilder = new StringBuilder();
while ( (receiveString = bufferedReader.readLine()) != null ) {
stringBuilder.append(receiveString);
}
inputStream.close();
data = stringBuilder.toString();
}
}
catch (FileNotFoundException e) {
Log.e("Error", "File not found: " + e.toString());
} catch (IOException e) {
Log.e("Error", "Can not read file: " + e.toString());
}
return data;
}
and your json can be
{
"variable1": "Value",
"variable2": false
}

Read persistance data when app is removed

i wanted to write and read data into/from a file.
I have searched and founnd these two methods which work perfectly..
public void writeToFile(String data,Context context) {
try {
OutputStreamWriter outputStreamWriter = new OutputStreamWriter(context.openFileOutput("config.txt", Context.MODE_PRIVATE));
outputStreamWriter.write(data);
outputStreamWriter.close();
}
catch (IOException e) {
Log.e("Exception", "File write failed: " + e.toString());
}
}
public String readFromFile(Context context) {
String ret = "";
try {
InputStream inputStream = context.openFileInput("config.txt");
if ( inputStream != null ) {
InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
String receiveString = "";
StringBuilder stringBuilder = new StringBuilder();
while ( (receiveString = bufferedReader.readLine()) != null ) {
stringBuilder.append(receiveString);
}
inputStream.close();
ret = stringBuilder.toString();
}
}
catch (FileNotFoundException e) {
Log.e("login activity", "File not found: " + e.toString());
} catch (IOException e) {
Log.e("login activity", "Can not read file: " + e.toString());
}
return ret;
}
But this file is being deleted when i remove the application from my android device.
Is there any method to save and retrieve data whatever if the user deleted the app ?

You can't. When removing an app, the files in it's local storage are removed.
You can however save your files in an external directory. That way, they aren't deleted when the user removes the app. You can read more about it here.

How to get a working HttpsUrlConnection with Steam Web API?

im currently trying to implement the Steam Web API using the given code in the following repository -> https://github.com/Overv/SteamWebAPI/blob/master/SteamAPISession.cs into my Android app and im getting different exceptions dependend on using the given wep api ip ( 63.228.223.110 ) or the adress ( https://api.steampowered.com/ ) itself.
my code actually looks like this in the given method when building up a connection to the web api:
private String steamRequest( String get, String post ) {
final int MAX_RETRIES = 3;
int numberOfTries = 0;
HttpsURLConnection request = null;
while(numberOfTries < MAX_RETRIES) {
if (numberOfTries != 0) {
Log.d(TAG, "Retry -> " + numberOfTries);
}
try {
request = (HttpsURLConnection) new URL("https://api.steampowered.com/" + get).openConnection(); //or 63.228.223.110/ ???
SSLSocketFactory socketFactory = (SSLSocketFactory) SSLSocketFactory.getDefault();
String host = "api.steampowered.com";
int port = 443;
int header = 0;
socketFactory.createSocket(new Socket(host, port), host, port, false);
request.setHostnameVerifier(new HostnameVerifier() {
#Override
public boolean verify(String s, SSLSession sslSession) {
return true;
}
});
request.setSSLSocketFactory(socketFactory);
request.setDoOutput(false);
// request.setRequestProperty("Host", "api.steampowered.com:443");
// request.setRequestProperty("Protocol-Version", "httpVersion");
request.setRequestProperty("Accept", "*/*");
request.setRequestProperty("Accept-Encoding", "gzip, deflate");
request.setRequestProperty("Accept-Language", "en-us");
request.setRequestProperty("User-Agent", "Steam 1291812 / iPhone");
request.setRequestProperty("Connection", "close");
if (post != null) {
byte[] postBytes;
try {
request.setRequestMethod("POST");
postBytes = post.getBytes("US-ASCII");
// request.setRequestProperty("Content-Length", Integer.toString(postBytes.length));
request.setFixedLengthStreamingMode(postBytes.length);
request.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
PrintWriter out = new PrintWriter(request.getOutputStream());
out.print(post);
out.close();
// DataOutputStream requestStream = new DataOutputStream(request.getOutputStream());
//// OutputStreamWriter stream = new OutputStreamWriter(request.getOutputStream());
//// stream.write(postBytes, 0, postBytes.length);
// requestStream.write(postBytes, 0, postBytes.length);
// requestStream.close();
message++;
} catch (ProtocolException e) {
e.printStackTrace();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
try {
int statusCode = request.getResponseCode();
InputStream is;
Log.d(TAG, "The response code of the status code is" + statusCode);
if (statusCode != 200) {
is = request.getErrorStream();
Log.d(TAG, String.valueOf(is));
}
// String src = null;
// OutputStreamWriter out = new OutputStreamWriter(request.getOutputStream());
// out.write(src);
// out.close();
Scanner inStream = new Scanner(request.getInputStream());
String response = "";
while (inStream.hasNextLine()) {
response += (inStream.nextLine());
}
// String src;
// BufferedReader in = new BufferedReader(new InputStreamReader(request.getInputStream()));
// StringBuilder builder = new StringBuilder();
// while ((src = in.readLine()) != null) {
// builder.append(src);
// }
// String jsonData = builder.toString();
Log.d(TAG, response); //jsonData
// in.close();
return response; //jsonData
} catch (MalformedURLException ex) {
Toast.makeText(getActivity(), ex.toString(), Toast.LENGTH_LONG).show();
ex.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
} catch (IOException e) {
e.printStackTrace();
} finally {
if (request != null) {
request.disconnect();
}
}
numberOfTries++;
}
Log.d(TAG, "Max retries reached. Giving up on connecting to Steam Web API...");
return null;
}
following exception occurs when using https://api.steampowered.com/ as url:
W/System.err﹕ java.io.FileNotFoundException: https://api.steampowered.com/ISteamOAuth2/GetTokenWithCredentials/v0001
D/OptionsFragment﹕ Failed to log in!
i've really tried and researched on those issues, but i just can't get a solution. If someone got a good hint on helping to solve these exceptions please let me know!
EDIT:
I've researched some more!
Looking up on https://partner.steamgames.com/documentation/webapi#creating the direct ip adress shouldn't be used and therefore only the DNS name itself (for further clarification look on the given link). Hence, looking up on the API interface list itself -> http://api.steampowered.com/ISteamWebAPIUtil/GetSupportedAPIList/v0001/?format=json there doesn't seem to be a given Interface with a method called ISteamOAuth2/GetTokenWithCredentials.(Or not anymore!) Only ISteamUserAuth and ISteamUserOAuth which seem to handle Authentication stuff.
I will update this post again if i should get a working connection and handling with the steam web api.
Cheers!

Fetch ip address of pc on android emulator through code android

I want to get the ip address of my pc in android emulator through code....or tell me to achive ip address of all devices connected in a lan to identify each one uniquely .......please help me to sort out this problem
Thanks in advance

The above functions are possible only by checking the arp cache where the IP address will be added one by one depending on how each one connect to the device. USe the below code and check. Just put button with proper name and call this method on click
public void getClientList() {
int macCount = 0;
BufferedReader br = null;
try {
br = new BufferedReader(new FileReader("/proc/net/arp"));
String line;
while ((line = br.readLine()) != null) {
String[] splitted = line.split(" +");
if (splitted != null && splitted.length >= 4) {
// Basic sanity check
String mac = splitted[3];
if (mac.matches("..:..:..:..:..:..")) {
macCount++;
ClientList.add("Client(" + macCount + ")");
IpAddr.add(splitted[0]);
HWAddr.add(splitted[3]);
Device.add(splitted[5]);
Toast.makeText(
getApplicationContext(),
"Mac_Count " + macCount + " MAC_ADDRESS "
+ mac, Toast.LENGTH_SHORT).show();
for (int i = 0; i < splitted.length; i++)
System.out.println("Addressssssss "
+ splitted[i]);
}
}
}
// ClientList.remove(0);
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
br.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}

use this code fetch the external ip address
HttpClient httpclient = new DefaultHttpClient();
HttpGet httpget = new HttpGet("http://api.externalip.net/ip/");
HttpResponse response = null;
try
{
response = httpclient.execute(httpget);
}
catch (ClientProtocolException e)
{
e.printStackTrace();
}
catch (IOException e)
{
e.printStackTrace();
}
Log.e("",""+response);
HttpEntity entity = response.getEntity();
if (entity != null) {
long len = entity.getContentLength();
if (len != -1 && len < 1024)
{
try
{
str=EntityUtils.toString(entity);
Log.e("",""+str);
}
catch (ParseException e)
{
e.printStackTrace();
}
catch (IOException e)
{
e.printStackTrace();
}
}
}

Android / Java: HttpURLConnection doesn't return headers of redirected file (e.g. on S3)

My code (reproduced below), connects to a url and downloads the file to disk on android. All standard stuff. When I try using this code on a file on S3 accessed via a subdomain on our server mapped to a bucket (e.g. foo.example.com => bucket called foo.example.com), it often fails. Turns out (using the handy curl command..
"curl -v -L -X GET http://foo.example.com/f/a.txt")
.. that there's a redirect going on here.
The file download works ok, as HttpURLConnection will follow redirects by default, but the calls that require the header infomation (getContentLength, getHeaderFieldDate("Last-Modified", 0 ) etc) are returns the headers from the 307 redirect, and not the actual file thats downloaded.
Anyone know how to get around this?
Thanks
File local = null;
try {
Log.i(TAG, "Downloading file " + source);
conn = (HttpURLConnection) new URL(source).openConnection();
fileSize = conn.getContentLength(); // ** THIS IS WRONG ON REDIRECTED FILES
out = new BufferedOutputStream(new FileOutputStream(destination, false), 8 * 1024);
conn.connect();
stream = new BufferedInputStream(conn.getInputStream(), 8 * 1024);
byte[] buffer = new byte[MAX_BUFFER_SIZE];
while (true) {
int read = stream.read(buffer);
if (read == -1) {
break;
}
// writing to buffer
out.write(buffer, 0, read);
downloaded += read;
publishProgress(downloaded, fileSize);
if (isCancelled()) {
return "The user cancelled the download";
}
}
} catch (Exception e) {
String msg = "Failed to download file " + source + ". " + e.getMessage();
Log.e(TAG, msg );
return msg;
} finally {
if (out != null) {
try {
out.flush();
out.close();
} catch (IOException e) {
Log.e(TAG, "Failed to close file " + destination);
e.printStackTrace();
}
}
if (stream != null) {
try {
stream.close();
} catch (IOException e) {
Log.e(TAG, "Failed to close file " + destination);
e.printStackTrace();
}
} else {
long dateLong = conn.getHeaderFieldDate("Last-Modified", 0 ); // ** THIS IS WRONG ON REDIRECTED FILES
Date d = new Date(dateLong);
local.setLastModified(dateLong);
}

have you tried to set redirects to false and try to manually capture the redirected URL and associated header fields with it?
For example something like this:
URL url = new URL(url);
HttpURLConnection ucon = (HttpURLConnection) url.openConnection();
ucon.setInstanceFollowRedirects(false);
URL secondURL = new URL(ucon.getHeaderField("Location"));
URLConnection conn = secondURL.openConnection();
This example captures the redirected URL, but you could easily tweak this to try for any other header field. Does this help?

Consider using httpclient-android. You should get the right headers after redirection with this:
HttpClient client = HttpClientBuilder.create().build();
HttpGet request = new HttpGet(YOUR_URL);
HttpResponse response = client.execute(request);
response.getAllHeaders()
Note that android comes with an older version of httpclient, but it has the same problem as you reported. You actually need to import "httpclient-android" for a newer version.
Note: The code snippet is for v4.3. For other versions, look for how to do it in regular apache HttpClient.

Well, I've been playing a bit and this code, which uses the HttpClient library rather than HttpUrlConnection works fine. The headers it returns are those of the final redirect hop.
At least on the devices I've tested it on.
HttpClient client = null;
HttpGet get = null;
HttpResponse response = null;
try {
client = new DefaultHttpClient();
get = new HttpGet(source);
response = client.execute(get);
Header contentSize = response.getFirstHeader("Content-Length");
if (contentSize != null) {
String value = contentSize.getValue();
fileSize = Long.parseLong(value);
}
if (fileSize == -1) {
Log.e(TAG, "Failed to read the content length for the file " + source);
}
Header lastModified = response.getFirstHeader("Last-Modified");
lastModifiedDate = null;
if (lastModified != null) {
lastModifiedDate = DateUtils.parseDate(lastModified.getValue());
}
if (lastModifiedDate == null) {
Log.e(TAG, "Failed to read the last modified date for the file " + source);
}
out = new BufferedOutputStream(new FileOutputStream(destination, false), 8 * 1024); // false means don't append
stream = new BufferedInputStream(response.getEntity().getContent(), 8 * 1024);
byte[] buffer = new byte[MAX_BUFFER_SIZE];
int count = 0;
while (true) {
int read = stream.read(buffer);
if (read == -1) {
break;
}
// writing to buffer
out.write(buffer, 0, read);
downloaded += read;
publishProgress(downloaded, fileSize);
if (isCancelled()) {
Log.w(TAG, "User Cancelled");
return; // NOTE that onPostExecute is not called here..
}
}// end of while
publishProgress(downloaded, fileSize);
} catch (Exception e) {
String msg = "Failed to download file " + source + ". " + e.getMessage();
Log.e(TAG, msg );
return msg;
} finally {
if (out != null) {
try {
out.flush();
out.close();
} catch (IOException e) {
Log.e(TAG, "Failed to close file " + destination);
e.printStackTrace();
}
}
if (stream != null) {
try {
stream.close();
} catch (IOException e) {
Log.e(TAG, "Failed to close file " + destination);
e.printStackTrace();
}
}
}