I have 3 url's of pages which content has a json structure. I must read a page from an url in an async task.
How can I read the 3 urls sequentially, so that I can work with the 3 json's maintaining their order?
private class JsonTask extends AsyncTask<String, String, String> {
protected void onPreExecute() {
super.onPreExecute();
}
protected String doInBackground(String... params) {
HttpURLConnection connection = null;
BufferedReader reader = null;
try {
URL url = new URL(params[0]); //params[0] = my first url
connection = (HttpURLConnection) url.openConnection();
connection.connect();
InputStream stream = connection.getInputStream();
reader = new BufferedReader(new InputStreamReader(stream));
StringBuffer buffer = new StringBuffer();
String line = "";
while ((line = reader.readLine()) != null) {
buffer.append(line + "\n");
}
return buffer.toString();
//read also the second and the third url
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
#Override
protected void onPostExecute(String result) {
// ... do something with the first json
// ... do something with the second json
// ... do something with the third json
}
}
Just move the logic for mapping one URL to JSON out into a method, and call it for each argument you pass in. Then, modify your AsyncTask so it outputs List<String> and not String from doInBackground().
protected List<String> doInBackground(String... params) {
final List<String> out = new ArrayList<>(paramas.length);
for(String url : params) {
out.add(downloadJson(url));
}
return out;
}
#Override
protected void onPostExecute(List<String> results) {
//A list of your JSON results...
}
private String downloadJson(String url) {
HttpURLConnection connection = null;
BufferedReader reader = null;
try {
connection = (HttpURLConnection) new URL(url).openConnection();
connection.connect();
InputStream stream = connection.getInputStream();
reader = new BufferedReader(new InputStreamReader(stream));
StringBuilder buffer = new StringBuilder();
String line = "";
while ((line = reader.readLine()) != null) {
buffer.append(line).append("\n");
}
return buffer.toString();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return "{}"; //Default to an empty JSON object
}
Related
Using AsyncTask freezes my whole app. i have an icon that rotates while the Http action is happening in the background. but the app just freezes till it finishes that action. Is there an alternative?
The below class sends the JSON to the server, the server has multiple endpoints and stuff like that. now when calling class calls the execute() method, the app freezes until the task is complete.
public class Connector extends AsyncTask<String, Void, Void> {
private String ip = "http://192.168.1.127";
private String port = "5000";
private URL Url;
private JSONObject jsonObject;
private String method = "";
private StringBuilder output = new StringBuilder();
Connector(String url, JSONObject jsonObject, String method)
{
try {
this.method = method;
this.Url = new URL(ip+":"+port+url);
} catch (MalformedURLException e) {
e.printStackTrace();
}
this.jsonObject = jsonObject;
//Connect to URL
}
#Override
protected Void doInBackground(String... strings) {
try {
HttpURLConnection httpURLConnection = (HttpURLConnection) Url.openConnection();
Log.i("Data", "Data sent => " + jsonObject.toString());
try {
httpURLConnection.setDoOutput(true);
httpURLConnection.setDoInput(true);
httpURLConnection.setRequestMethod(method);
httpURLConnection.setRequestProperty("content-type", "application/json");
httpURLConnection.connect();
DataOutputStream outputStream = new DataOutputStream(httpURLConnection.getOutputStream());
if(jsonObject != null)
{
outputStream.writeBytes(jsonObject.toString());
outputStream.flush();
outputStream.close();
}
InputStreamReader inputStreamReader = new InputStreamReader((InputStream) httpURLConnection.getContent(), Charset.forName("UTF-8"));
BufferedReader reader = new BufferedReader(inputStreamReader);
String line = reader.readLine();
while(line != null)
{
output.append(line);
line = reader.readLine();
}
}finally {
httpURLConnection.disconnect();
}
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(Void aVoid) {
super.onPostExecute(aVoid);
}
#Override
protected void onPreExecute() {
super.onPreExecute();
}
String getMessge() {
Log.i("Data", "Data received <= " + output.toString());
return output.toString();
}
}
Please use Retrofit library.
You can find samples to use Retrofit easily.
https://www.journaldev.com/13639/retrofit-android-example-tutorial
This is one of them.
Hope it to help you. Thanks.
public class PerformNetworkTasks extends AsyncTask<String, String, String> {
#Override
protected String doInBackground(String... params) {
HttpURLConnection connection = null;
BufferedReader reader = null;
try {
URL url = new URL(params[0]);
connection = (HttpURLConnection) url.openConnection();
connection.connect(); //getting the connection to the URL to read JSON data
InputStream stream = connection.getInputStream();
reader = new BufferedReader(new InputStreamReader(stream));
StringBuffer buffer = new StringBuffer();
String line = "";
while ((line = reader.readLine()) != null) {
buffer.append(line);
}
String jsonText = buffer.toString(); // gets what the URL returns as JSON
JSONObject obj = new JSONObject(jsonText); // using JSONObject to pass to a JSONArray to search for the JSON
List<String> allInfo = new ArrayList<String>(); // list to put all the returned information
JSONArray linemanques = obj.getJSONArray("linemanques"); //selects the array to read from
for (int i = 0; i < linemanques.length(); i++) {
JSONObject questionParts = linemanques.getJSONObject(i);
quesnum = questionParts.getString("quesnum"); // all of questionParts.getString() are for getting the data in the JSONArray
questype = questionParts.getString("questype");
question = questionParts.getString("question");
ans1 = questionParts.getString("ans1");
ans2 = questionParts.getString("ans2");
ans3 = questionParts.getString("ans3");
ans4 = questionParts.getString("ans4");
correctans = questionParts.getString("correctans");
category = questionParts.getString("category");
notes = questionParts.getString("notes");
flag = questionParts.getString("flag");
allInfo.add(quesnum);
allInfo.add(questype);
allInfo.add(question);
allInfo.add(ans1);
allInfo.add(ans2);
allInfo.add(ans3);
allInfo.add(ans4);
allInfo.add(correctans);
allInfo.add(category);
allInfo.add(notes);
allInfo.add(flag);
allInfo.add("\n");
}
return allInfo.toString();
/*
right now I am returning the list as a String,
so that I can actually view the data.
I need to put this data into their own TextViews.
So how can I return the list I have so that I can set
the individual TextViews as one section from the list?
*/
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
} finally {
}
if (connection != null) {
connection.disconnect();
}
try {
if (reader != null) {
reader.close();
}
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
inputDataTV.setText(result);
}
I need to return some data individually. So I need to return an array (i think) so that I can set the TextView as e.g. arrays.get(number).
Is there some other way that I am not realizing here, or should I continue with what I am doing to get the data individually?
Just to add, I am getting the info from a website.
You can return any data type you want
but your AsyncTask structure should be based on result data type
public class PerformNetworkTasks extends AsyncTask<String, String, List<String>/*resultParam*/> {
#Override
protected List<String>/*will same as result parma*/ doInBackground(String... params) {
return null;/*now you can return list of string*/
}
#Override
protected void onPostExecute(List<String>/*finally receive result*/ result) {
super.onPostExecute(result);
}
}
so your code will be
public class PerformNetworkTasks extends AsyncTask<String, String, List<String>> {
#Override
protected List<String> doInBackground(String... params) {
HttpURLConnection connection = null;
BufferedReader reader = null;
try {
URL url = new URL(params[0]);
connection = (HttpURLConnection) url.openConnection();
connection.connect(); //getting the connection to the URL to read JSON data
InputStream stream = connection.getInputStream();
reader = new BufferedReader(new InputStreamReader(stream));
StringBuffer buffer = new StringBuffer();
String line = "";
while ((line = reader.readLine()) != null) {
buffer.append(line);
}
String jsonText = buffer.toString(); // gets what the URL returns as JSON
JSONObject obj = new JSONObject(jsonText); // using JSONObject to pass to a JSONArray to search for the JSON
List<String> allInfo = new ArrayList<>(); // list to put all the returned information
JSONArray linemanques = obj.getJSONArray("linemanques"); //selects the array to read from
for (int i = 0; i < linemanques.length(); i++) {
JSONObject questionParts = linemanques.getJSONObject(i);
quesnum = questionParts.getString("quesnum"); // all of questionParts.getString() are for getting the data in the JSONArray
questype = questionParts.getString("questype");
question = questionParts.getString("question");
ans1 = questionParts.getString("ans1");
ans2 = questionParts.getString("ans2");
ans3 = questionParts.getString("ans3");
ans4 = questionParts.getString("ans4");
correctans = questionParts.getString("correctans");
category = questionParts.getString("category");
notes = questionParts.getString("notes");
flag = questionParts.getString("flag");
allInfo.add(quesnum);
allInfo.add(questype);
allInfo.add(question);
allInfo.add(ans1);
allInfo.add(ans2);
allInfo.add(ans3);
allInfo.add(ans4);
allInfo.add(correctans);
allInfo.add(category);
allInfo.add(notes);
allInfo.add(flag);
allInfo.add("\n");
}
return allInfo;
/*
right now
I am returning the list as a String,
so that I can actually view the data.
I need to put this data into their own TextViews.
So how can I return the list I have so that I can set
the individual TextViews as one section from the list?
*/
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
} finally {
}
if (connection != null) {
connection.disconnect();
}
try {
if (reader != null) {
reader.close();
}
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(List<String> result) {
super.onPostExecute(result);
inputDataTV.setText(result.get(0));
}
}
I'm trying to send POST request via HttpURLConnection, here is the code
public class BackgroundTask extends AsyncTask<String, Void, Void> {
Context context;
Activity activity;
StringBuffer str = null;
int responseCode;
String responseMessage;
public BackgroundTask(Context context) {
this.context = context;
this.activity = (Activity) context;
}
#Override
protected Void doInBackground(String... params) {
HttpURLConnection connection = null;
OutputStream outputStream = null;
InputStream inputStream = null;
BufferedReader reader = null;
BufferedWriter writer = null;
String method = params[1];
if(method.equals("post")) {
try {
URL url = new URL(params[0]);
connection = (HttpURLConnection) url.openConnection();
connection.setDoOutput(true);
connection.setRequestMethod("POST");
connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
outputStream = connection.getOutputStream();
writer = new BufferedWriter(new OutputStreamWriter(outputStream, "UTF-8"));
String data = URLEncoder.encode(params[2] + "=" + params[3], "UTF-8");
writer.write(data);
responseCode = connection.getResponseCode();
responseMessage = connection.getResponseMessage();
inputStream = connection.getInputStream();
reader = new BufferedReader(new InputStreamReader(inputStream));
str = new StringBuffer();
String line = "";
while ((line = reader.readLine()) != null) {
str.append(line);
}
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (connection != null)
connection.disconnect();
if (reader != null) {
try {
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (writer != null) {
try {
writer.flush();
writer.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (inputStream != null) {
try {
inputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (outputStream != null) {
try {
outputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
} else if(method.equals("get")) {
}
return null;
}
#Override
protected void onProgressUpdate(Void... values) {
super.onProgressUpdate(values);
}
#Override
protected void onPostExecute(Void aVoid) {
TextView txt = (TextView) activity.findViewById(R.id.txt);
if(str != null)
txt.setText(str.toString());
Toast.makeText(activity, responseMessage, Toast.LENGTH_LONG).show();
}
}
responseCode is 200 which means everything went OK, however it says Undefined index: id
id is well defined inside php file
$user = User::find_by_id($_POST['id']);
echo json_encode($user);
and it works fine when I send post request from an html file yet when i send it from application it says id undefined which means that POST data is not sent.
btn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
BackgroundTask myTask = new BackgroundTask(MainActivity.this);
myTask.execute(link, "post", "id", "5");
}
});
this is how i instantiate asynctask object inside main activity
UPDATE: when i send not encoded string it works fine!
writer.write("id=5"); // works perfectly!
what is wrong with URLEncoder i use in the code?
I believe you have a problem in this line:
String data = URLEncoder.encode(params[2] + "=" + params[3], "UTF-8");
You are url-encoding the = as well as the params, that's why the server cannot recognise the form fields. Try to encode the params only:
String data = URLEncoder.encode(params[2], "UTF-8") + "=" + URLEncoder.encode(params[3], "UTF-8");
The reason is that URL encoding is for passing special characters like = in the value(or key). Basically, the server will split and parse the key-value pairs with & and = before doing the decoding. And when you url-encode the = character, the server simply couldn't recognise it during the split and parse phase.
When i need to communicate with the server i use this
Server Class
public static String sendPostRequest(String requestURL,
HashMap<String, String> postDataParams) {
URL url;
String response = "";
try {
url = new URL(requestURL);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setReadTimeout(15000);
conn.setConnectTimeout(15000);
conn.setRequestMethod("POST");
conn.setDoInput(true);
conn.setDoOutput(true);
OutputStream os = conn.getOutputStream();
BufferedWriter writer = new BufferedWriter(
new OutputStreamWriter(os, "UTF-8"));
writer.write(getPostDataString(postDataParams));
writer.flush();
writer.close();
os.close();
int responseCode = conn.getResponseCode();
if (responseCode == HttpsURLConnection.HTTP_OK) {
BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));
response = br.readLine();
} else {
response = "Error Registering";
}
} catch (Exception e) {
e.printStackTrace();
}
return response;
}
private static String getPostDataString(HashMap<String, String> params) throws UnsupportedEncodingException {
StringBuilder result = new StringBuilder();
boolean first = true;
for (Map.Entry<String, String> entry : params.entrySet()) {
if (first)
first = false;
else
result.append("&");
result.append(URLEncoder.encode(entry.getKey(), "UTF-8"));
result.append("=");
result.append(URLEncoder.encode(entry.getValue(), "UTF-8"));
}
return result.toString();
}
OtherClass
//Run this inside an Asynctask
HashMap<String,String> data = new HashMap<>();
data.put("id", id);
String serverResponce = Server.sendPostRequest(URL,data);
I'm implementing JSP page in my Android application. I don't know how to use JSP Url in Android. I tried and run the application. But the page is blank does not show any info in Android layout and also in log cat. Here is my code.
public class JSP_Activity extends Activity
{
public static String strUrl=null;
String strText = null;
public void OnCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.jsp_page);
connectWithGet_JspPage();
}
private void connectWithGet_JspPage()
{
class GetJspPage extends AsyncTask<String, Void, String>
{
#Override
protected String doInBackground(String... strUrls)
{
// TODO Auto-generated method stub
strUrl="http://test.window2india.com/mobile/home.jsp";
Log.e("strUrl :=","" + strUrl);
String strOutPut = null;
strOutPut=getOutPutFromUrl(strUrl);
Log.e("strOutPut :="," "+strOutPut);
return strOutPut.toString();
}
protected void onPostExecute(String output1)
{
//outputText.setText(output1);
Log.e("strOutPut :="," "+output1);
}
}
GetJspPage getJspPageAsyncTask = new GetJspPage();
getJspPageAsyncTask.execute();
}
private String getOutPutFromUrl(String url)
{
StringBuffer output = new StringBuffer("");
try
{
InputStream stream = getHttpConnection(url);
BufferedReader buffer = new BufferedReader(new InputStreamReader(stream));
String s = "";
while ((s = buffer.readLine()) != null)
output.append(s);
}
catch (IOException e1)
{
e1.printStackTrace();
}
return output.toString();
}
private InputStream getHttpConnection(String urlString)
throws IOException
{
InputStream stream = null;
URL url = new URL(urlString);
URLConnection connection = url.openConnection();
try
{
HttpURLConnection httpConnection = (HttpURLConnection) connection;
httpConnection.setRequestMethod("GET");
httpConnection.connect();
if (httpConnection.getResponseCode() == HttpURLConnection.HTTP_OK)
{
stream = httpConnection.getInputStream();
}
}
catch (Exception ex)
{
ex.printStackTrace();
}
return stream;
}
}
Try this code,it will help for display the content send by the jsp.This code is useful for normal layout not for webview.You have to parse the content and display in your custom layout.
new Thread(new Runnable()
{
public void run()
{
try
{
URL url = new URL("http://test.window2india.com/mobile/home.jsp");
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
InputStream in = new BufferedInputStream(urlConnection.getInputStream());
BufferedReader r = new BufferedReader(new InputStreamReader(in));
String x = "";
String total = "";
int i=0;
ArrayList<String> content = new ArrayList();
while((x = r.readLine()) != null)
{
content.add(x);
}
in.close();
r.close();
}
catch(Exception e)
{
e.printStackTrace();
}
}
}).start();
I need to download .html file from some URL. How can I do it? And how can I convert it to String?
UPDATED:
I have no idea why you downvoting. I can get the desired result on iOS by only using one method stringWithContentsOfURL:encoding:error:. And I suggested that Android has similar. method
Code below downloads html page from link, and return html page converted to string in completion callback
public class HTMLPageDownloader extends AsyncTask<Void, Void, String> {
public static interface HTMLPageDownloaderListener {
public abstract void completionCallBack(String html);
}
public HTMLPageDownloaderListener listener;
public String link;
public HTMLPageDownloader (String aLink, HTMLPageDownloaderListener aListener) {
listener = aListener;
link = aLink;
}
#Override
protected String doInBackground(Void... params) {
// TODO Auto-generated method stub
HttpClient client = new DefaultHttpClient();
HttpGet request = new HttpGet(link);
String html = "";
try {
HttpResponse response = client.execute(request);
InputStream in;
in = response.getEntity().getContent();
BufferedReader reader = new BufferedReader(
new InputStreamReader(in));
StringBuilder str = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
str.append(line);
}
in.close();
html = str.toString();
} catch (IllegalStateException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return html;
}
#Override
protected void onPostExecute(String result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
if (!isCancelled()) {
listener.completionCallBack(result);
}
}
}
How's this:
URL url;
InputStream is = null;
DataInputStream dis;
String line;
String out = "";
try {
url = new URL("http://www.example.com/");
is = url.openStream(); // throws an IOException
dis = new DataInputStream(new BufferedInputStream(is));
while ((line = dis.readLine()) != null) {
out.append(line);
}
} catch (MalformedURLException mue) {
mue.printStackTrace();
} catch (IOException ioe) {
ioe.printStackTrace();
} finally {
try {
is.close();
} catch (IOException ioe) {
}
}
You can use http://jsoup.org library
or
URL url = new URL("http://www.android.com/");
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
try {
InputStream in = new BufferedInputStream(urlConnection.getInputStream());
readStream(in);
}finally {
urlConnection.disconnect();
}
and covert Input Stream to String
BufferedReader br = new BufferedReader(new InputStreamReader(is));
StringBuilder sb = new StringBuilder();
String line;
while ((line = br.readLine()) != null) {
sb.append(line);
}
System.out.println(sb.toString());
br.close();
You could use HttpURLConnection, streams, and a ReadableByteChannel.
I feel this helps down the line for adding request info to the connection.
try {
URL test = new URL(/* link to your resource */);
HttpURLConnection httpcon = (HttpURLConnection) test.openConnection();
httpcon.addRequestProperty("User-Agent", "Mozilla/5.0");
ReadableByteChannel rbc = Channels.newChannel(httpcon.getInputStream());
FileOutputStream fos = new FileOutputStream(/* File output here */);
fos.getChannel().transferFrom(rbc, 0, 1 << 24);
fos.close();
} catch (FileNotFoundException ex) {
ex.printStackTrace();
} catch (IOException ex) {
ex.printStackTrace();
}