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Android - Size in chars of an http response

I am not an pro developing android. I wanted to download a JSON object from my server, but only code I could find was this:
private String downloadUrl(String myurl) throws IOException {
InputStream is = null;
// Only display the first 500 characters of the retrieved
// web page content.
int len = 500;
try {
URL url = new URL(myurl);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setReadTimeout(10000 /* milliseconds */);
conn.setConnectTimeout(15000 /* milliseconds */);
conn.setRequestMethod("GET");
conn.setDoInput(true);
// Starts the query
conn.connect();
int response = conn.getResponseCode();
Log.d("ServerConnection", "The response is: " + response);
is = conn.getInputStream();;
//is.
// Convert the InputStream into a string
String contentAsString = readIt(is, len);
return contentAsString;
// Makes sure that the InputStream is closed after the app is
// finished using it.
} catch (MalformedURLException e) {
//
return "error";
} catch (IOException e) {
//
return "error";
} finally {
if (is != null) {
is.close();
}
}
}
And it works fine, I cant understand. But it has a int len = 500, and my returned json is cropped to 500 chars. I tried changing to a great number, but it puts spaces at the end. How can I know the size in chars of the String contained by the InputSteam?
Thanks

You can check the Content-Length header value of your response:
Map<String, List<String>> headers = connection.getHeaderFields();
for (Entry<String, List<String>> header : headers.entrySet()) {
if(header.getKey().equals("Content-Legth")){
len=Integer.parseInt(header.getValue());
}
}
or you can your response in a buffered reader like this:
InputStream is = connection.getInputStream();
InputStreamReader reader = new InputStreamReader(is);
StringBuilder builder = new StringBuilder();
int c = 0;
while ((c = reader.read()) != -1) {
builder.append((char) c);
}

Yout can use Apache Commons IO IOUtils.toString to convert InputStream to String or use Gson to read object from input stream directly:
return gson.fromJson(new InputStreamReader(inputStream), YourType.class);

Cannot read large JSON request data from input stream even after using few variations

I am using post man to send the JSon request. Then I get the inputStream using the getInputStream().
InputStream inputStream = request.getInputStream();
I have a JSon request with 2032 character and it might increase based on the scenarios. I tried few suggestions for the similar kind of issue, but using all I would be able to read only 1011 character.
Below are the ways which I tried.
Declarations:
BufferedReader bufferedReader = null;
StringBuilder stringBuilder = new StringBuilder();
// stringBuilder.ensureCapacity(1048576);
JSONObject jObj = null;
InputStream inputStream = request.getInputStream();
1)
bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
char[] charBuffer = new char[1048576];
int bytesRead = -1;
while ((bytesRead = bufferedReader.read(charBuffer)) > 0) {
stringBuilder.append(charBuffer, 0, bytesRead);
}
2)
bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
String line = "";
String result = "";
while ((line = bufferedReader.readLine()) != null)
result += line;
inputStream.close();
3)
String line;
try {
bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
while ((line = bufferedReader.readLine()) != null) {
stringBuilder.append(line);
}
} catch (Exception e) {
// TODO: handle exception
}
4)
stringBuilder.ensureCapacity(1048576);
BoundedInputStream boundedInputStream = new BoundedInputStream(inputStream);
bufferedReader = new BufferedReader(new InputStreamReader(boundedInputStream, "UTF-8"));
// StringBuilder builder= new StringBuilder();
StringBuilderWriter bufferedwriter = new StringBuilderWriter(stringBuilder);
IOUtils.copy(bufferedReader, bufferedwriter);
5)
bufferedReader = request.getReader();
char[] charBuffer = new char[1048576];
int bytesRead = -1;
while ((bytesRead = bufferedReader.read(charBuffer)) > 0) {
stringBuilder.append(charBuffer, 0, bytesRead);
}
Final Consumption: Used the second variation result was my latest try
// jObj = new JSONObject(stringBuilder.toString());
// jObj = new JSONObject(bufferedwriter.toString());
jObj = new JSONObject(result.toString());
Note: I was just verifying by increasing the char capacity to 1048576 to see if that would solve. But increasing that also have no effect on the inputstream.
Could anyone of you please advise me on how to read large Json input. Also let me know if I am doing it wrong.
Thanks in advance.

You seem to want to convert the JSON into a String. With Java 8 this has become a bit simpler.
// (1)
try (BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream))) {
// (2)
String json = reader.lines().collect(Collectors.joining("\n"));
// do something with `json`...
}
Explained:
Create a BufferedReader from the input stream. Using "try-with-resources" means, that the reader will be automatically closed when leaving the try {} block.
The BufferedReader has a method lines() which returns a Stream<String>. You can simply join all Strings using the joining collector.

HTTP GET request in java returns meaningless data from App Engine

I'm requesting a json file from an App Engine URL
http://1-1-26a.wordbuzzweb.appspot.com/json/level-images.json
The file encoding is UTF-8 without a BOM. If I look at this file on my local disk it's size is 12414 bytes. If I get the file in Chrome is reads it perfectly well. If I then save it it's 12414 bytes. However, if I try and download the file with a GET request in java I only get 780 bytes returned and the returned data would appear to be meaningless.
I've tried several different types of get request, both of the methods below I have used elsewhere perfectly effectively. The response code on the GET requests is 200. Interestingly, if I do a POST with no content instead of a GET, then I get the valid response.
If I download the file from this URL on Google Drive instead, then the GET methods below work perfectly.
edit This code is now working, however, this is a recurring issue that comes and goes. If anyone has any ideas what might be causing it then please say so!
This doesn't work
public static String doGetSync(String urlToRead) throws IOException {
URL url = new URL(urlToRead);
InputStream is = url.openStream();
ByteArrayOutputStream buffer = new ByteArrayOutputStream();
int nRead;
byte[] data = new byte[BUFFER_SIZE];
while ((nRead = is.read(data, 0, data.length)) != -1) {
buffer.write(data, 0, nRead);
}
buffer.flush();
byte[] bytes = buffer.toByteArray();
return new String(bytes, "UTF-8");
}
Neither does this
public static String doGetSync2(String urlToRead) throws IOException {
final String charset = "UTF-8";
// Create the connection
HttpURLConnection connection = (HttpURLConnection) new URL(urlToRead).openConnection();
// Check the error stream first, if this is null then there have been no issues with the request
InputStream inputStream = connection.getErrorStream();
if (inputStream == null)
inputStream = connection.getInputStream();
// Read everything from our stream
BufferedReader responseReader = new BufferedReader(new InputStreamReader(inputStream, charset));
String inputLine;
StringBuilder response = new StringBuilder();
while ((inputLine = responseReader.readLine()) != null) {
response.append(inputLine);
}
responseReader.close();
return response.toString();
}
This code works
public static String doPostSync(final String url, final String content) throws IOException {
final String charset = "UTF-8";
// Create the connection
HttpURLConnection connection = (HttpURLConnection) new URL(url).openConnection();
// setDoOutput(true) implicitly set's the request type to POST
connection.setDoOutput(true);
connection.setRequestProperty("Accept-Charset", charset);
connection.setRequestProperty("Content-type", "application/json");
// Write to the connection
OutputStream output = connection.getOutputStream();
output.write(content.getBytes(charset));
output.close();
// Check the error stream first, if this is null then there have been no issues with the request
InputStream inputStream = connection.getErrorStream();
if (inputStream == null)
inputStream = connection.getInputStream();
// Read everything from our stream
BufferedReader responseReader = new BufferedReader(new InputStreamReader(inputStream, charset));
String inputLine;
StringBuilder response = new StringBuilder();
while ((inputLine = responseReader.readLine()) != null) {
response.append(inputLine);
}
responseReader.close();
return response.toString();
}

Grabbing JSON works from one link, not from another

I'm doing a simple JSON grab from two links with the same code. I'm doing it two separate times, so the cause of my issue isn't because they're running into each other or something.
Here is my code:
#Override
protected String doInBackground(Object... params) {
try {
URL weatherUrl = new URL("my url goes here");
HttpURLConnection connection = (HttpURLConnection) weatherUrl
.openConnection();
connection.connect();
responseCode = connection.getResponseCode();
if (responseCode == HttpURLConnection.HTTP_OK) {
InputStream inputStream = connection.getInputStream();
Reader reader = new InputStreamReader(inputStream);
int contentLength = connection.getContentLength();
char[] charArray = new char[contentLength];
reader.read(charArray);
String responseData = new String(charArray);
Log.v("test", responseData);
When I try this with:
http://www.google.com/calendar/feeds/developer-calendar#google.com/public/full?alt=json
I get an error of having an array lenth of -1
For this link:
http://api.openweathermap.org/data/2.5/weather?id=5815135
It returns fine and I get a log of all of the JSON. Does anyone have any idea why?
Note: I tried stepping through my code in debug mode, but I couldn't catch anything. I also downloaded a Google chrome extension for parsing json in the browser and both urls look completely valid. I'm out of ideas.

Log this: int contentLength = connection.getContentLength();
I don't see the google url returning a content-length header.
If you just want String output from a url, you can use Scanner and URL like so:
Scanner s = new Scanner(new URL("http://www.google.com").openStream(), "UTF-8").useDelimiter("\\A");
out = s.next();
s.close();
(don't forget try/finally block and exception handling)
The longer way (which allows for progress reporting and such):
String convertStreamToString(InputStream is) throws UnsupportedEncodingException {
BufferedReader reader = new BufferedReader(new
InputStreamReader(is, "UTF-8"));
StringBuilder sb = new StringBuilder();
String line = null;
try {
while ((line = reader.readLine()) != null)
sb.append(line + "\n");
} catch (IOException e) {
// Handle exception
} finally {
try {
is.close();
} catch (IOException e) {
// Handle exception
}
}
return sb.toString();
}
}
and then call String response = convertStreamToString( inputStream );

UTF-8 response with servlet

I am reading HTTP response from a Perl page in a Servlet like this:
public String getHTML(String urlToRead) {
URL url;
HttpURLConnection conn;
BufferedReader rd;
String line;
String result = "";
try {
url = new URL(urlToRead);
conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
conn.setRequestProperty("Accept-Charset", "UTF-8");
conn.setRequestProperty("Content-Type", "text/xml; charset=UTF-8");
rd = new BufferedReader(new InputStreamReader(conn.getInputStream(), "UTF-8"));
while ((line = rd.readLine()) != null) {
byte [] b = line.getBytes();
result += new String(b, "UTF-8");
}
rd.close();
} catch (Exception e) {
e.printStackTrace();
}
return result;
}
I am displaying this result with this code:
response.setContentType("text/plain; charset=UTF-8");
PrintWriter out = new PrintWriter(new OutputStreamWriter(response.getOutputStream(), "UTF-8"), true);
try {
String query = request.getParameter("query");
String type = request.getParameter("type");
String res = getHTML(url);
out.write(res);
} finally {
out.close();
}
But the response still is not encoded as UTF-8. What am I doing wrong?
Thanks in advance.

That call to line.getBytes() looks suspicious. You should probably make it line.getBytes("UTF-8") if you are certain that what is returned is UTF-8 encoded. Additionally, I'm not sure why it is even necessary. A typical approach to getting data out of a BufferedReader is to use a StringBuilder to continue appending each String retrieved from readLine into a result. The conversion back and forth between String and byte[] is unnecessary.
Change result into a StringBuilder and do this:
while ((line = rd.readLine()) != null) {
result.append(line);
}

Here is where you break the chain of character encoding conversions:
while ((line = rd.readLine()) != null) {
byte [] b = line.getBytes(); // NOT UTF-8
result += new String(b, "UTF-8");
}
From String#getBytes() javadoc:
Encodes this String into a sequence of bytes using the platform's
default charset, storing the result into a new byte array
And, defaullt charset is probably not UTF-8.
But why do all the conversions in the first place? Just read the raw bytes from the source and write the raw bytes to the consumer. It's supposed to be UTF-8 all the way.

I also faced the same problem in another scenario, but just do it I believe it will work:
byte[] b = line.getBytes(UTF8_CHARSET);
in the while loop:
while ((line = rd.readLine()) != null) {
byte [] b = line.getBytes(); // NOT UTF-8
result += new String(b, "UTF-8");
}

In my case, I have do add another configuration.
Previously, I was writing the page this way:
try (PrintStream printStream = new PrintStream(response.getOutputStream()) {
printStream.print(pageInjecting);
}
I changed to:
try (PrintStream printStream = new PrintStream(response.getOutputStream(), false, "UTF-8")) {
printStream.print(pageInjecting);
}