Android: Getting HTTP response incrementally like in iOS - android

I'm relatively new to Android (I'm an iOS-Developer) and I want to call a Webservice like I'm used to in iOS with NSURLConnectionDelegate's method
didReceiveData:(NSData *)data
I need to get the data incrementally because I'm building a streaming API that gets a lot of JSON data in response and needs to check the data for complete blocks.
Would be great if someone could help me, I've been searching for a while and didn't find a satisfying solution so far.

If you try to call web services in Android you should use the AsyncTask where the request would be made asynchronously. Have a look at the documentation. Every time you're request would be finished the method onPostExecute(Object result) would be called. Thats the method where you can go on with further processes.

The URLConnection documentation contain following example:
URL url = new URL("ftp://mirror.csclub.uwaterloo.ca/index.html");
URLConnection urlConnection = url.openConnection();
InputStream in = new BufferedInputStream(urlConnection.getInputStream());
try {
readStream(in);
finally {
in.close();
}
If i right understood your question, just implement readStream function as you need.

I found out how to do this with the help of a friend and some links.
You need to implement an own ResponseHandler like this:
class ChunkedResponseHandler implements ResponseHandler<String> {
#Override
public String handleResponse(HttpResponse response) throws ClientProtocolException, IOException {
HttpEntity entity = response.getEntity();
InputStream stream = entity.getContent();
StringBuffer output = new StringBuffer();
byte[] b = new byte[4096];
int n;
while ((n = stream.read(b)) != -1) {
output.append(new String(b, 0, n));
// do something while input is streaming
}
return output.toString();
}
}
Now you simply have to assign the response handler when starting the request:
HttpClient client = new DefaultHttpClient();
HttpGet getRequest = new HttpGet("someURL");
ResponseHandler<String> responseHandler = new ChunkedResponseHandler();
String responseBody = client.execute(postRequest, responseHandler);

Related

Get JSON from URL - deprecated method?

I have been using this code to get JSON from a specified URL, but today I checked it, and everything in it is deprecated. It still works fine, but I want to know what is the new method of doing it?
Here's what I have:
#Override
protected String doInBackground(String... params) {
try {
HttpClient client = new DefaultHttpClient();
StringBuilder url = new StringBuilder("some url");
HttpGet hg = new HttpGet(url.toString());
HttpResponse hr = client.execute(hg);
int status = hr.getStatusLine().getStatusCode();
if (status == 200) {
HttpEntity he = hr.getEntity();
String data = EntityUtils.toString(he);
jsonGet = new JSONObject(data);
}
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
The deprecated objects are HttpClient, HttpGet, HttpResponse, HttpEntity and EntityUtils.
EDIT: As suggested in some questions, this way
HttpClient client = HttpClientBuilder.create().build();
does not work for me, as I am getting HttpClientBuilder cannot be resolved
Apache httpClient is deprecated with api level 22 you can read it about this blog.
there is a new client for android now and it is very good.
but you can use okhttp instead (also back compat is possible).
EDIT
check this link(URL.openConnection()). this blog was posted in 2011 but they mentioned the deprecation there first as far as i know.
First of all you have to search well on Google.
Here is your answer may it will helps you.
The HttpClient documentation points you in the right direction:
org.apache.http.client.HttpClient:
This interface was deprecated in API level 22.
Please use openConnection() instead. Please visit this webpage for further details.
means that you should switch to java.net.URL.openConnection().
Here's how you could do it:
URL url = new URL("http://some-server");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("POST");
// read the response
System.out.println("Response Code: " + conn.getResponseCode());
InputStream in = new BufferedInputStream(conn.getInputStream());
String response = org.apache.commons.io.IOUtils.toString(in, "UTF-8");
System.out.println(response);
IOUtils documentation: Apache Commons IO
IOUtils Maven dependency: http://search.maven.org/#artifactdetails|org.apache.commons|commons-io|1.3.2|jar
Special Thanks to fateddy for this answer

Getting json response from servlet to Android

I have a servlet that has the following purpose:
Receive data via the URL (that is, using get). Then returns a message, based on this input, back to the caller. I am new to this stuff, but have come to learn that using json (actually, Gson) is suitable for this.
My question now is, how do I retrieve this json message? What URL do I target? The relevant lines in the servlet are:
String json = new Gson().toJson(thelist);
response.setContentType("application/json");
response.setCharacterEncoding("UTF-8");
response.getWriter().println(json);
This is how I try to retrieve the json:
try{
DefaultHttpClient defaultClient = new DefaultHttpClient();
HttpGet httpGetRequest = new HttpGet("http://AnIPno:8181/sample/response?first=5&second=92866");
HttpResponse httpResponse = defaultClient.execute(httpGetRequest);
BufferedReader reader = new BufferedReader(new InputStreamReader(httpResponse.getEntity().getContent(), "UTF-8"));
String json = reader.readLine();
JSONObject jsonObject = new JSONObject(json);
} catch(Exception e){
e.printStackTrace();
}
But apparently this does not work, as I have found jsonObject has a size of 0 (it should be an array with three elements).
Previously, I had a write() instead of println() in the servlet. I'm not sure if that matters in this case. But I'm assuming I've misunderstood something about how the json object is retrieved. Is it not enough to point it towards the URL of the servlet?
Reading an InputStream whether from a File on the file system or from an HTTP request is, in most cases, the same.
What you have is correct only if your servlet wrote a single line. If the Gson object toString() method returns multiple lines, you're going to have to read multiple lines from the InputStream. I like to use the Scanner class for reading from an InputStream.
try {
DefaultHttpClient defaultClient = new DefaultHttpClient();
HttpGet httpGetRequest = new HttpGet("http://localhost:8080/cc/jsonyeah");
HttpResponse httpResponse = defaultClient.execute(httpGetRequest);
Scanner scanner = new Scanner(httpResponse.getEntity().getContent(), "UTF-8");
while(scanner.hasNextLine()) { // scanner looks ahead for an end-of-line
json += scanner.nextLine() + "\n"; // read the full line, you can append a \n
}
// do your serialization
} catch(Exception e) {
e.printStackTrace();
}
So we've done the same thing we would've done if we were reading from a file. Now the json object contains the json you received from the servlet, as a String.
For the serialization, you have a few options.
A Gson object has an overloaded method fromJson() that can take a String or a Reader, among other things.
From where we are with the code above, you can do
MyClass instance = new Gson().fromJson(json, MyClass.class);
where MyClass is the type you are trying to create. You will have to use a TypeToken for generic classes (such as a list). TypeToken is an abstract class, so generate an anonymous class and call getType()
Type type = new com.google.gson.reflect.TypeToken<List<String>>(){}.getType();
List<MyClass> list = new Gson().fromJson(json, type);
Another option is to use the overloaded method that takes a Reader directly instead of reading line by line from the InputStream:
BufferedReader reader = new BufferedReader(new InputStreamReader(httpResponse.getEntity().getContent(), "UTF-8"));
MyClass instance = new Gson().fromJson(reader , MyClass.class);
You'll get to skip a step.
Don't forget to close your streams.
I have this function to readJsonData from a a request to a JSON String. You can use this function to retrieve the JSON, then use GSON to parse it to the object that you like. It works for my application. Hope it works for you too.
protected String readJson(HttpResponse resp)
throws IOException {
BufferedReader reader = null;
try {
reader = new BufferedReader(new InputStreamReader(
resp.getEntity().getContent()));
StringBuffer buffer = new StringBuffer();
int read;
char[] chars = new char[1024];
while ((read = reader.read(chars)) != -1)
buffer.append(chars, 0, read);
} finally {
if (reader != null)
reader.close();
}
return buffer.toString();
}
So based on your code. I guess this should work:
String jsonData = readJson(httpResponse);
YourObject obj = new Gson().fromJson(jsonData, YourObject.class);
Before trying this, make sure your servlet prints out the JSON data that you want. I suggest using these Chrome Extensions: Postman - REST Client and JSON Formatter, to test your data from servlet. It's pretty helpful.

calling RESTful WCFservice method with object as parameter from java

i have a RESTful WCF service and one of its methods use an Object as parameter
[WebInvoke(UriTemplate = "save", Method = "POST", RequestFormat = WebMessageFormat.Xml, ResponseFormat= WebMessageFormat.Xml), OperationContract]
public SampleItem Create(SampleItem instance)
{
return new SampleItem() { Id = 1, StringValue = "saved" };
// TODO: Add the new instance of SampleItem to the collection
//throw new NotImplementedException();
}
I am trying to call this method from my eclipse android project. i am using these lines of codes
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost post=new HttpPost("http://10.0.2.2:2768/Service1.svc/save");
ArrayList<NameValuePair> nvp= new ArrayList<NameValuePair>();
nvp.add(new BasicNameValuePair("Id", "1"));
nvp.add(new BasicNameValuePair("StringValue", "yolo"));
post.setEntity(new UrlEncodedFormEntity(nvp));
HttpResponse httpResponse = httpClient.execute(post);
HttpEntity httpEntity = httpResponse.getEntity();
String xml = EntityUtils.toString(httpEntity);
Every time i get this error Method not allowed. in the XML that is returned by the service method.
i have tried invoking it from the browser, but encountered the same error there.
please tell me what i am doing wrong and what i can do instead.
thanks in advance to anyone who can help.
note: other methods which do not use object as parameter are working fine.
EDIT: tried Fiddler2 with success. but stalled again.
i have tried invoking the method SampleItem Create(SampleItem instance) with the url http://localhost:2768/Service1.svc/save and it works. the method returns the object in XML format.
in fiddler i added the request body as
<SampleItem xmlns="http://schemas.datacontract.org/2004/07/WcfRestService1" xmlns:i="http://www.w3.org/2001/XMLSchema-instance"><Id>1</Id><StringValue>saved</StringValue></SampleItem>
but the problem is that i can not find any way to add this xml string to the HttpPost or HttpRequest as the requestbody eclipse android project.
note: passing the xml string as Header or UrlEncodedFormEntity did not work.
finally i have succeeded to send a json object over to my WCF Service here's my code
URI uri = new URI("http://esimsol.com/droidservice/pigeonlibrary.service1.svc/save");
JSONObject jo1 = new JSONObject();
jo1.put("Id", "4");
jo1.put("StringValue", "yollo");
HttpURLConnection conn = (HttpURLConnection) uri.toURL().openConnection();
conn.setRequestProperty("Content-Type","application/json; charset=utf-8");
conn.setRequestProperty("Accept", "application/json");
conn.setRequestProperty("User-Agent", "Pigeon");
conn.setChunkedStreamingMode(0);
conn.setDoInput(true);
conn.setDoOutput(true);
conn.setRequestMethod("POST");
conn.connect();
DataOutputStream out = new DataOutputStream(conn.getOutputStream());
out.write(jo1.toString().getBytes());
out.flush();
int code = conn.getResponseCode();
String message = conn.getResponseMessage();
InputStream in = conn.getInputStream();
StringBuffer sb = new StringBuffer();
String reply;
try {
int chr;
while ((chr = in.read()) != -1) {
sb.append((char) chr);
}
reply = sb.toString();
} finally {
in.close();
}
SampleItem SI = new SampleItem();
SI=new Gson().fromJson(reply, SampleItem.class);
Toast.makeText(getApplicationContext(), SI.getStringValue(),Toast.LENGTH_LONG).show();
conn.disconnect();
thanks to StackOverFlow.
i had to combine a number of code snippets to achieve this.
First, you should get the Web Service method working from the browser - I recommend using Fiddler2 - its easier to construct the request body with your object and also to set the request headers when doing a post. It will show you the response so should help with debugging.
As for your code, I'm doing a POST to a WCF service and instead of doing
post.setEntity(new UrlEncodedFormEntity(nvp));
I'm simply doing:
HttpPost request = new HttpPost(url);
// Add headers.
for(NameValuePair h : headers)
{
request.addHeader(h.getName(), h.getValue());
}
(I am using JSONObjects and I have RequestFormat = WebMessageFormat.Json in my WebInvoke parameters.
Also, check your using the correct UriTemplate name in your url as they are case sensitive.
To call that WCF service you must build valid SOAP request and post it. It is better to use some SOAP protocol stack on Android - for example kSoap2.
Here is example of using kSoap2 to call WCF service.
just add KSOAP2 lib in your project.for how we add KSOAP2 in Android project see this post

How to send POST request in JSON using HTTPClient in Android?

I'm trying to figure out how to POST JSON from Android by using HTTPClient. I've been trying to figure this out for a while, I have found plenty of examples online, but I cannot get any of them to work. I believe this is because of my lack of JSON/networking knowledge in general. I know there are plenty of examples out there but could someone point me to an actual tutorial? I'm looking for a step by step process with code and explanation of why you do each step, or of what that step does. It doesn't need to be a complicated, simple will suffice.
Again, I know there are a ton of examples out there, I'm just really looking for an example with an explanation of what exactly is happening and why it is doing that way.
If someone knows about a good Android book on this, then please let me know.
Thanks again for the help #terrance, here is the code I described below
public void shNameVerParams() throws Exception{
String path = //removed
HashMap params = new HashMap();
params.put(new String("Name"), "Value");
params.put(new String("Name"), "Value");
try {
HttpClient.SendHttpPost(path, params);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
In this answer I am using an example posted by Justin Grammens.
About JSON
JSON stands for JavaScript Object Notation. In JavaScript properties can be referenced both like this object1.name and like this object['name'];. The example from the article uses this bit of JSON.
The Parts
A fan object with email as a key and foo#bar.com as a value
{
fan:
{
email : 'foo#bar.com'
}
}
So the object equivalent would be fan.email; or fan['email'];. Both would have the same value
of 'foo#bar.com'.
About HttpClient Request
The following is what our author used to make a HttpClient Request. I do not claim to be an expert at all this so if anyone has a better way to word some of the terminology feel free.
public static HttpResponse makeRequest(String path, Map params) throws Exception
{
//instantiates httpclient to make request
DefaultHttpClient httpclient = new DefaultHttpClient();
//url with the post data
HttpPost httpost = new HttpPost(path);
//convert parameters into JSON object
JSONObject holder = getJsonObjectFromMap(params);
//passes the results to a string builder/entity
StringEntity se = new StringEntity(holder.toString());
//sets the post request as the resulting string
httpost.setEntity(se);
//sets a request header so the page receving the request
//will know what to do with it
httpost.setHeader("Accept", "application/json");
httpost.setHeader("Content-type", "application/json");
//Handles what is returned from the page
ResponseHandler responseHandler = new BasicResponseHandler();
return httpclient.execute(httpost, responseHandler);
}
Map
If you are not familiar with the Map data structure please take a look at the Java Map reference. In short, a map is similar to a dictionary or a hash.
private static JSONObject getJsonObjectFromMap(Map params) throws JSONException {
//all the passed parameters from the post request
//iterator used to loop through all the parameters
//passed in the post request
Iterator iter = params.entrySet().iterator();
//Stores JSON
JSONObject holder = new JSONObject();
//using the earlier example your first entry would get email
//and the inner while would get the value which would be 'foo#bar.com'
//{ fan: { email : 'foo#bar.com' } }
//While there is another entry
while (iter.hasNext())
{
//gets an entry in the params
Map.Entry pairs = (Map.Entry)iter.next();
//creates a key for Map
String key = (String)pairs.getKey();
//Create a new map
Map m = (Map)pairs.getValue();
//object for storing Json
JSONObject data = new JSONObject();
//gets the value
Iterator iter2 = m.entrySet().iterator();
while (iter2.hasNext())
{
Map.Entry pairs2 = (Map.Entry)iter2.next();
data.put((String)pairs2.getKey(), (String)pairs2.getValue());
}
//puts email and 'foo#bar.com' together in map
holder.put(key, data);
}
return holder;
}
Please feel free to comment on any questions that arise about this post or if I have not made something clear or if I have not touched on something that your still confused about... etc whatever pops in your head really.
(I will take down if Justin Grammens does not approve. But if not then thanks Justin for being cool about it.)
Update
I just happend to get a comment about how to use the code and realized that there was a mistake in the return type.
The method signature was set to return a string but in this case it wasnt returning anything. I changed the signature
to HttpResponse and will refer you to this link on Getting Response Body of HttpResponse
the path variable is the url and I updated to fix a mistake in the code.
Here is an alternative solution to #Terrance's answer. You can easly outsource the conversion. The Gson library does wonderful work converting various data structures into JSON and the other way around.
public static void execute() {
Map<String, String> comment = new HashMap<String, String>();
comment.put("subject", "Using the GSON library");
comment.put("message", "Using libraries is convenient.");
String json = new GsonBuilder().create().toJson(comment, Map.class);
makeRequest("http://192.168.0.1:3000/post/77/comments", json);
}
public static HttpResponse makeRequest(String uri, String json) {
try {
HttpPost httpPost = new HttpPost(uri);
httpPost.setEntity(new StringEntity(json));
httpPost.setHeader("Accept", "application/json");
httpPost.setHeader("Content-type", "application/json");
return new DefaultHttpClient().execute(httpPost);
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
Similar can be done by using Jackson instead of Gson. I also recommend taking a look at Retrofit which hides a lot of this boilerplate code for you. For more experienced developers I recommend trying out RxAndroid.
I recommend using this HttpURLConnectioninstead HttpGet. As HttpGet is already deprecated in Android API level 22.
HttpURLConnection httpcon;
String url = null;
String data = null;
String result = null;
try {
//Connect
httpcon = (HttpURLConnection) ((new URL (url).openConnection()));
httpcon.setDoOutput(true);
httpcon.setRequestProperty("Content-Type", "application/json");
httpcon.setRequestProperty("Accept", "application/json");
httpcon.setRequestMethod("POST");
httpcon.connect();
//Write
OutputStream os = httpcon.getOutputStream();
BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(os, "UTF-8"));
writer.write(data);
writer.close();
os.close();
//Read
BufferedReader br = new BufferedReader(new InputStreamReader(httpcon.getInputStream(),"UTF-8"));
String line = null;
StringBuilder sb = new StringBuilder();
while ((line = br.readLine()) != null) {
sb.append(line);
}
br.close();
result = sb.toString();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
Too much code for this task, checkout this library https://github.com/kodart/Httpzoid
Is uses GSON internally and provides API that works with objects. All JSON details are hidden.
Http http = HttpFactory.create(context);
http.get("http://example.com/users")
.handler(new ResponseHandler<User[]>() {
#Override
public void success(User[] users, HttpResponse response) {
}
}).execute();
There are couple of ways to establish HHTP connection and fetch data from a RESTFULL web service. The most recent one is GSON. But before you proceed to GSON you must have some idea of the most traditional way of creating an HTTP Client and perform data communication with a remote server. I have mentioned both the methods to send POST & GET requests using HTTPClient.
/**
* This method is used to process GET requests to the server.
*
* #param url
* #return String
* #throws IOException
*/
public static String connect(String url) throws IOException {
HttpGet httpget = new HttpGet(url);
HttpResponse response;
HttpParams httpParameters = new BasicHttpParams();
// Set the timeout in milliseconds until a connection is established.
// The default value is zero, that means the timeout is not used.
int timeoutConnection = 60*1000;
HttpConnectionParams.setConnectionTimeout(httpParameters, timeoutConnection);
// Set the default socket timeout (SO_TIMEOUT)
// in milliseconds which is the timeout for waiting for data.
int timeoutSocket = 60*1000;
HttpConnectionParams.setSoTimeout(httpParameters, timeoutSocket);
HttpClient httpclient = new DefaultHttpClient(httpParameters);
try {
response = httpclient.execute(httpget);
HttpEntity entity = response.getEntity();
if (entity != null) {
InputStream instream = entity.getContent();
result = convertStreamToString(instream);
//instream.close();
}
}
catch (ClientProtocolException e) {
Utilities.showDLog("connect","ClientProtocolException:-"+e);
} catch (IOException e) {
Utilities.showDLog("connect","IOException:-"+e);
}
return result;
}
/**
* This method is used to send POST requests to the server.
*
* #param URL
* #param paramenter
* #return result of server response
*/
static public String postHTPPRequest(String URL, String paramenter) {
HttpParams httpParameters = new BasicHttpParams();
// Set the timeout in milliseconds until a connection is established.
// The default value is zero, that means the timeout is not used.
int timeoutConnection = 60*1000;
HttpConnectionParams.setConnectionTimeout(httpParameters, timeoutConnection);
// Set the default socket timeout (SO_TIMEOUT)
// in milliseconds which is the timeout for waiting for data.
int timeoutSocket = 60*1000;
HttpConnectionParams.setSoTimeout(httpParameters, timeoutSocket);
HttpClient httpclient = new DefaultHttpClient(httpParameters);
HttpPost httppost = new HttpPost(URL);
httppost.setHeader("Content-Type", "application/json");
try {
if (paramenter != null) {
StringEntity tmp = null;
tmp = new StringEntity(paramenter, "UTF-8");
httppost.setEntity(tmp);
}
HttpResponse httpResponse = null;
httpResponse = httpclient.execute(httppost);
HttpEntity entity = httpResponse.getEntity();
if (entity != null) {
InputStream input = null;
input = entity.getContent();
String res = convertStreamToString(input);
return res;
}
}
catch (Exception e) {
System.out.print(e.toString());
}
return null;
}

Connecting to a webserver with android

I have to connect to a webserver from android and I have to access a webservice and a webpage from the webserver. Can anybody help me? Please give step by step process with some code snippets because I am new to android and I don't know anything in connecting to a webserver.
You can use an HttpClient:
HttpClient httpClient = new DefaultHttpClient();
HttpGet httpGet = new HttpGet(uri);
HttpResponse httpResponse = httpClient.execute(httpGet);
BufferedReader reader = new BufferedReader(
new InputStreamReader(httpResponse.getEntity().getContent()));
// user reader to read & parse response
reader.close();
Parsing the response obviously depends on the format (e.g. SOAP, JSON, etc.)
You haven't given very much info (what kind of web page, XML/JSON/HTML/etc. ?). But the basic principles of regular Java apply. Using URL and InputStream:
URL url = new URL(...);
InputStream is = url.openStream();
And from there it depends what kind of data you're dealing with.
If you don't want to use an additional library, here is a means for sending an "id" and "name" to a server:
URL url = null;
try {
String registrationUrl = String.format("http://myserver/register?id=%s&name=%s", myId, URLEncoder.encode(myName,"UTF-8"));
url = new URL(registrationUrl);
URLConnection connection = url.openConnection();
HttpURLConnection httpConnection = (HttpURLConnection) connection;
int responseCode = httpConnection.getResponseCode();
if (responseCode == HttpURLConnection.HTTP_OK) {
Log.d("MyApp", "Registration success");
} else {
Log.w("MyApp", "Registration failed for: " + registrationUrl);
}
} catch (Exception ex) {
ex.printStackTrace();
}
You could just as easily send other data via this URI "GET" style, but if you need to send something more detailed a POST will be required.
Note: Originally posted to answer a similar question here: How to connect android to server

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