We Keep Coding

How to get response from a http connection in android

I'm trying to handle this API http://worldtimeapi.org
Here is my code :
#Nullable
public String getResponseFromHttpUrl(#NonNull URL gotUrl) {
Log.v(LOG_TAG, "URI : " + gotUrl);
String timeJSONString = null;
HttpURLConnection urlConnection = null;
BufferedReader bufferedReader = null;
try {
urlConnection = (HttpURLConnection) gotUrl.openConnection();
InputStream inputStream = urlConnection.getInputStream();
bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
StringBuilder stringBuilder = new StringBuilder();
String line;
while ((line = bufferedReader.readLine()) != null) {
stringBuilder.append(line);
stringBuilder.append("\n");
}
if (stringBuilder.length() == 0) {
// Stream was empty. No point in parsing.
return null;
}
timeJSONString = stringBuilder.toString();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (urlConnection != null) {
urlConnection.disconnect();
}
if (bufferedReader != null) {
try {
bufferedReader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
Log.d(LOG_TAG, "Response : " + timeJSONString);
return timeJSONString;
}
But the problem is my method returns null.
As you can see in below:
V/NetworkUtils: URI : http://worldtimeapi.org/api/timezone/America/Denver
W/System.err: at com.example.timeonearth.NetworkUtils.getResponseFromHttpUrl(NetworkUtils.java:56)
D/NetworkUtils: Response : null

You need to Try getting the input stream from this you can then get the text data as so:-->
URL url;
HttpURLConnection urlConnection = null;
try {
url = new URL("http://worldtimeapi.org/api/timezone/America/Denver");
urlConnection = (HttpURLConnection) url
.openConnection();
InputStream in = urlConnection.getInputStream();
InputStreamReader isw = new InputStreamReader(in);
int data = isw.read();
while (data != -1) {
char current = (char) data;
data = isw.read();
System.out.print(current);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
if (urlConnection != null) {
urlConnection.disconnect();
}
}
You can probably use other Inputstream readers such as buffered reader also.
The problem is that when you open the connection - it does not 'pull' any data.

Using HttpUrlconnection in Rss Reader causes Android to hang

I put together an RSS reader that works as-is but, I want to setup the connection to the RSS URL using HttpUrlConnection method. When I tried it, the program locked up after I clicked Read Rss button:
private class getRssFeedTask extends AsyncTask<String, Void, String> {
#Override
protected String doInBackground(String... params) {
try {
URL rssUrl = new URL(params[0]);
HttpURLConnection urlIn = (HttpURLConnection) rssUrl.openConnection();
InputStream in = new BufferedInputStream(urlIn.getInputStream());
String line;
feed = "";
while ((line = in.toString()) != null) {
feed += line;
}
in.close();
return feed;
} catch (MalformedURLException ue) {
System.out.println("Malformed URL");
} catch (IOException ioe) {
System.out.println("The URL is unreachable");
}
return null;
}
}
This is the connection method I am stuck using which works:
private class getRssFeedTask extends AsyncTask<String, Void, String> {
#Override
protected String doInBackground(String... params) {
try {
URL rssUrl = new URL(params[0]);
BufferedReader in = new BufferedReader(new InputStreamReader(rssUrl.openStream()));
String line;
feed = "";
while ((line = in.readLine()) != null) {
feed += line;
}
in.close();
return feed;
} catch (MalformedURLException ue) {
System.out.println("Malformed URL");
} catch (IOException ioe) {
System.out.println("The URL is unreachable");
}
return null;
}
}
Thanks for any help you can provide!

What you need to do is put it into a string I called it results. I have attached my code for the doInBackground. By adding it to a string it has a place to store the feed. And it works for the rss reader.
public String doInBackground(String... urls){
String result = "";
try{
URL url = new URL(urls[0]);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
InputStream in = conn.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(in));
String line = "";
while((line = reader.readLine()) != null){
result = result + line;
}
conn.disconnect();
}
catch(Exception e){
Log.e("ERROR Fetching ", e.toString());
}
return result;
}

How to pass and read string from android to sql using JSON

Previously, i can access the string from php remotely. I find it difficult at first but AsyncTask did the work for me. Now, i can access the result of the query from php to sql server. But I would like to pass a string from my java class to php and as I googled some information, i saw some JSON post and get codes but i can't clearly understand them. Here's my code:
protected String doInBackground(Void... params) {
BufferedReader br = null;
StringBuilder sb = new StringBuilder();
String url = "http://122.2.8.226/MITBookstore/sqlconnect.php";
HttpURLConnection urlConnection = null;
String line;
try {
urlConnection = (HttpURLConnection) new URL(url).openConnection();
InputStream in = urlConnection.getInputStream();
br = new BufferedReader(new InputStreamReader(in));
while ((line = br.readLine()) != null) {
sb.append(line);
}
}
catch (Exception e) {
e.printStackTrace();
}
finally {
if (br != null) {
try {
br.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
return sb.toString();
The string is contained in "sb.toString()". Now how would I add a JSON something in my code to send string from java to php, and also get the result string from php to java as well. Thanks in advance for any help.

If you receive response as JSON format from server, make the json string to JSONObject first. And then read the json data for your use.
try {
JSONObject obj = new JSONObject(sb.toString()); // make string to json obj
Iterator iter = obj.keys(); // get all keys from json obj and iterating
while(iter.hasNext()){
String key = (String)iter.next();
String str = obj.get(key).toString();
// write your code
}
} catch(Exception e) {
e.printStackTrace();
}
Your code already contains the answer of your question. After make url connection, just add parameter for sending your data to server with OutputStreamWriter as like you did for receive the response with InpustStreamReader.
BufferedReader br = null;
StringBuilder sb = new StringBuilder();
String url = "http://122.2.8.226/MITBookstore/sqlconnect.php";
HttpURLConnection urlConnection = null;
String line;
try {
urlConnection = (HttpURLConnection) new URL(url).openConnection();
// wrtie params
OutputStreamWriter we = new OutputStreamWriter(urlConnection.getOutPutStream());
wr.write(data); // data (make json obj to 'key=value' string)
wr.flush();
wr.close();
// read response
InputStream in = urlConnection.getInputStream();
br = new BufferedReader(new InputStreamReader(in));
while ((line = br.readLine()) != null) {
sb.append(line);
}
}
catch (Exception e) {
e.printStackTrace();
}
finally {
if (br != null) {
try {
br.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}enter code here

Catch errors of HttpUrlConnection in AsyncTask

I'm searching for a best practice to handle errors in an HttpURLConnection especially if the host is not available. How did I have to change my source?:
protected String doInBackground(String... strings) {
URL aURL;
String line;
HttpURLConnection connection;
BufferedReader reader;
StringBuilder stringBuilder = null;
try {
aURL = new URL(strings[0]);
connection = (HttpURLConnection) aURL.openConnection();
InputStream aInputStream = connection.getInputStream();
BufferedInputStream aBufferedInputStream = new BufferedInputStream(aInputStream);
reader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
stringBuilder = new StringBuilder();
while ((line = reader.readLine()) != null)
{
stringBuilder.append(line);
}
} catch (IOException e) {
Log.d("svc", e.toString());
}
return stringBuilder.toString();
}

you will get different responsecode using connection.getResponseCode()
Check for the response codes for host not available and you will be set.

How to read an HTTP input stream?

The code pasted below was taken from Javadocs on HttpURLConnection.
I get the following error:
readStream(in)
...as there is no such method.
I see this same thing in the Class Overview for URLConnection at
URLConnection.getInputStream
Where is readStream? The code snippet is provided below:
URL url = new URL("http://www.android.com/");
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
try
{
InputStream in = new BufferedInputStream(urlConnection.getInputStream());
readStream(in); <-----NO SUCH METHOD
}
finally
{
urlConnection.disconnect();
}

Try with this code:
InputStream in = address.openStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(in));
StringBuilder result = new StringBuilder();
String line;
while((line = reader.readLine()) != null) {
result.append(line);
}
System.out.println(result.toString());

It looks like the documentation is just using readStream() to mean:
Ok, we've shown you how to get the InputStream, now your code goes in readStream()
So you should either write your own readStream() method which does whatever you wanted to do with the data in the first place.

Spring has an util class for that:
import org.springframework.util.FileCopyUtils;
InputStream is = connection.getInputStream();
ByteArrayOutputStream bos = new ByteArrayOutputStream();
FileCopyUtils.copy(is, bos);
String data = new String(bos.toByteArray());

try this code
String data = "";
InputStream iStream = httpEntity.getContent();
BufferedReader br = new BufferedReader(new InputStreamReader(iStream, "utf8"));
StringBuffer sb = new StringBuffer();
String line = "";
while ((line = br.readLine()) != null) {
sb.append(line);
}
data = sb.toString();
System.out.println(data);

a complete code for reading from a webservice in two ways
public void buttonclick(View view) {
// the name of your webservice where reactance is your method
new GetMethodDemo().execute("http://wervicename.nl/service.asmx/reactance");
}
public class GetMethodDemo extends AsyncTask<String, Void, String> {
//see also:
// https://developer.android.com/reference/java/net/HttpURLConnection.html
//writing to see: https://docs.oracle.com/javase/tutorial/networking/urls/readingWriting.html
String server_response;
#Override
protected String doInBackground(String... strings) {
URL url;
HttpURLConnection urlConnection = null;
try {
url = new URL(strings[0]);
urlConnection = (HttpURLConnection) url.openConnection();
int responseCode = urlConnection.getResponseCode();
if (responseCode == HttpURLConnection.HTTP_OK) {
server_response = readStream(urlConnection.getInputStream());
Log.v("CatalogClient", server_response);
}
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
try {
url = new URL(strings[0]);
urlConnection = (HttpURLConnection) url.openConnection();
BufferedReader in = new BufferedReader(new InputStreamReader(
urlConnection.getInputStream()));
String inputLine;
while ((inputLine = in.readLine()) != null)
System.out.println(inputLine);
in.close();
Log.v("bufferv ", server_response);
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
Log.e("Response", "" + server_response);
//assume there is a field with id editText
EditText editText = (EditText) findViewById(R.id.editText);
editText.setText(server_response);
}
}