How can I split the HttpUrlConnection logic into multiple methods?

Question

I have several Acts, each of which receives different data from different URLs and different HTTP methods, such as POST , GET , PUT , DELETE , etc. Some queries have header data, while some have Body, some can have both. I use a single AsyncTask class with several constructors to pass data from Acts so I can add it to an HttpUrlConnection instance.

I tried this tutorial: http://cyriltata.blogspot.in/2013/10/android-re-using-asynctask-class-across.html .

But the above guide uses HttpClient and NameValuePair . I replaced NameValuePair with Pair . But it's hard for me to implement the same logic with the HttpUrlConnection , since I need to add some data and POST headers to my request.

But the returned string is empty. How to implement this scenario?

Full code:

 public class APIAccessTask extends AsyncTask<String,Void,String> { URL requestUrl; Context context; HttpURLConnection urlConnection; List<Pair<String,String>> postData, headerData; String method; int responseCode = HttpURLConnection.HTTP_NOT_FOUND; APIAccessTask(Context context, String requestUrl, String method){ this.context = context; this.method = method; try { this.requestUrl = new URL(requestUrl); } catch(Exception ex){ ex.printStackTrace(); } } APIAccessTask(Context context, String requestUrl, String method, List<Pair<String,String>> postData,){ this(context, requestUrl, method); this.postData = postData; } APIAccessTask(Context context, String requestUrl, String method, List<Pair<String,String>> postData, List<Pair<String,String>> headerData){ this(context, requestUrl,method,postData); this.headerData = headerData; } @Override protected void onPreExecute() { super.onPreExecute(); } @Override protected String doInBackground(String... params) { setupConnection(); if(method.equals("POST")) { return httpPost(); } if(method.equals("GET")) { return httpGet(); } if(method.equals("PUT")) { return httpPut(); } if(method.equals("DELETE")) { return httpDelete(); } if(method.equals("PATCH")) { return httpPatch(); } return null; } @Override protected void onPostExecute(String result) { Toast.makeText(context,result,Toast.LENGTH_LONG).show(); super.onPostExecute(result); } void setupConnection(){ try { urlConnection = (HttpURLConnection) requestUrl.openConnection(); urlConnection.setDoOutput(true); urlConnection.setDoInput(true); urlConnection.setChunkedStreamingMode(0); if(headerData != null){ for (Pair pair: headerData) { urlConnection.setRequestProperty(pair.first.toString(), Base64.encodeToString(pair.second.toString().getBytes(),Base64.DEFAULT)); } } } catch(Exception ex) { ex.printStackTrace(); } } private String httpPost(){ try{ urlConnection.setRequestMethod("POST"); } catch (Exception ex){ ex.printStackTrace(); return stringifyResponse(); } String httpGet(){ try{ urlConnection.setRequestMethod("GET"); } catch (Exception ex){ ex.printStackTrace(); } return stringifyResponse(); } String httpPut(){ try{ urlConnection.setRequestMethod("PUT"); } catch (Exception ex){ ex.printStackTrace(); } return stringifyResponse(); } String httpDelete(){ try{ urlConnection.setRequestMethod("DELETE"); } catch (Exception ex){ ex.printStackTrace(); } return stringifyResponse(); } String httpPatch(){ try{ urlConnection.setRequestMethod("PATCH"); } catch (Exception ex){ ex.printStackTrace(); } return stringifyResponse(); } String stringifyResponse() { StringBuilder sb = new StringBuilder(); try { OutputStream out = new BufferedOutputStream(urlConnection.getOutputStream()); BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(out, "UTF-8")); writer.write(getQuery(postData)); writer.flush(); writer.close(); out.close(); urlConnection.connect(); responseCode = urlConnection.getResponseCode(); if (responseCode == 200) { InputStream in = new BufferedInputStream(urlConnection.getInputStream()); BufferedReader reader = new BufferedReader(new InputStreamReader(in, "UTF-8")); String line = null; while ((line = reader.readLine()) != null) { sb.append(line); } } } catch (Exception ex) { ex.printStackTrace(); } return sb.toString(); } private String getQuery(List<Pair<String,String>> params) throws UnsupportedEncodingException{ Uri.Builder builder = null; for (Pair pair : params) { builder = new Uri.Builder() .appendQueryParameter(pair.first.toString(), pair.second.toString()); } return builder.build().getEncodedQuery(); } } 

Answer 1

IMO, you can refer to the following sample code:

  /** * HTTP request using HttpURLConnection * * @param method * @param address * @param header * @param mimeType * @param requestBody * @return * @throws Exception */ public static URLConnection makeURLConnection(String method, String address, String header, String mimeType, String requestBody) throws Exception { URL url = new URL(address); HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection(); urlConnection.setDoInput(true); urlConnection.setDoOutput(!method.equals(HTTP_METHOD_GET)); urlConnection.setRequestMethod(method); if (isValid(header)) { // let assume only one header here urlConnection.setRequestProperty(KEYWORD_HEADER_1, header); } if (isValid(requestBody) && isValid(mimeType) && !method.equals(HTTP_METHOD_GET)) { urlConnection.setRequestProperty(KEYWORD_CONTENT_TYPE, mimeType); OutputStream outputStream = new BufferedOutputStream(urlConnection.getOutputStream()); BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(outputStream, "utf-8"); writer.write(requestBody); writer.flush(); writer.close(); outputStream.close(); } urlConnection.connect(); return urlConnection; } 

requestBody is executed using the following method:

  public static String buildRequestBody(Object content) { String output = null; if ((content instanceof String) || (content instanceof JSONObject) || (content instanceof JSONArray)) { output = content.toString(); } else if (content instanceof Map) { Uri.Builder builder = new Uri.Builder(); HashMap hashMap = (HashMap) content; if (isValid(hashMap)) { Iterator entries = hashMap.entrySet().iterator(); while (entries.hasNext()) { Map.Entry entry = (Map.Entry) entries.next(); builder.appendQueryParameter(entry.getKey().toString(), entry.getValue().toString()); entries.remove(); // avoids a ConcurrentModificationException } output = builder.build().getEncodedQuery(); } } else if (content instanceof byte[]) { try { output = new String((byte[]) content, "UTF-8"); } catch (UnsupportedEncodingException e) { e.printStackTrace(); } } return output; } } 

Then in the AsyncTask class you can call:

  String url = "http://......."; HttpURLConnection urlConnection; Map<String, String> stringMap = new HashMap<>(); stringMap.put(KEYWORD_USERNAME, "bnk"); stringMap.put(KEYWORD_PASSWORD, "bnk123"); String requestBody = buildRequestBody(stringMap); try { urlConnection = (HttpURLConnection) Utils.makeURLConnection(HTTP_METHOD_POST, url, null, MIME_FORM_URLENCODED, requestBody); if (urlConnection.getResponseCode() == HttpURLConnection.HTTP_OK) { // do something... } else { // do something... } ... } catch (Exception e) { e.printStackTrace(); } 

or

  String url = "http://......."; HttpURLConnection urlConnection; JSONObject jsonBody; String requestBody; try { jsonBody = new JSONObject(); jsonBody.put("Title", "Android Demo"); jsonBody.put("Author", "BNK"); requestBody = Utils.buildRequestBody(jsonBody); urlConnection = (HttpURLConnection) Utils.makeURLConnection(HTTP_METHOD_POST, url, null, MIME_JSON, requestBody); if (urlConnection.getResponseCode() == HttpURLConnection.HTTP_OK) { // do something... } else { // do something... } ... } catch (Exception e) { e.printStackTrace(); } 

Answer 2

Let's apply some oops concepts here
Have an HttpCommunication class that will only execute a request to send a request and receive a response from the server. Sample code that looks like this

 package com.example.sample; import java.io.BufferedReader; import java.io.InputStream; import java.io.InputStreamReader; import java.util.ArrayList; import org.apache.http.HttpEntity; import org.apache.http.HttpResponse; import org.apache.http.NameValuePair; import org.apache.http.client.entity.UrlEncodedFormEntity; import org.apache.http.client.methods.HttpGet; import org.apache.http.client.methods.HttpPost; import org.apache.http.client.utils.URLEncodedUtils; import org.apache.http.impl.client.DefaultHttpClient; import org.apache.http.params.BasicHttpParams; import org.apache.http.params.HttpConnectionParams; import org.apache.http.params.HttpParams; public class HttpCommunication { public String makeHttpRequest( String url, HttpMethods method, ArrayList< NameValuePair > requestParams, ArrayList< NameValuePair > postData ) throws Exception { InputStream inputStream = null; String 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 = 15000; HttpConnectionParams.setConnectionTimeout( httpParameters, timeoutConnection ); /** * Set the default socket timeout (SO_TIMEOUT) in milliseconds which is the timeout for * waiting for data. */ int timeoutSocket = 15000; HttpConnectionParams.setSoTimeout( httpParameters, timeoutSocket ); DefaultHttpClient httpClient = new DefaultHttpClient( httpParameters ); /** * Check for request method */ if ( method == HttpMethods.POST ) { HttpPost httpPost = new HttpPost( url ); if ( requestParams != null && requestParams.size( ) > 0 ) { httpPost.setEntity( new UrlEncodedFormEntity( requestParams ) ); } HttpResponse httpResponse = httpClient.execute( httpPost ); HttpEntity httpEntity = httpResponse.getEntity( ); inputStream = httpEntity.getContent( ); } else if ( method == HttpMethods.GET ) { if ( requestParams != null && requestParams.size( ) > 0 ) { String paramString = URLEncodedUtils.format( requestParams, "utf-8" ); url += "?" + paramString; } HttpGet httpGet = new HttpGet( url ); HttpResponse httpResponse = httpClient.execute( httpGet ); HttpEntity httpEntity = httpResponse.getEntity( ); inputStream = httpEntity.getContent( ); } BufferedReader reader = new BufferedReader( new InputStreamReader( inputStream, "UTF-8" ) ); StringBuilder sb = new StringBuilder( ); String line = null; while ( ( line = reader.readLine( ) ) != null ) { sb.append( line + "\n" ); } inputStream.close( ); response = sb.toString( ); return response; } } 

Have an abstract base class that will act as a template for all the major web services in your application. This class will use the HttpCommunication class above to send the request. Requests will be sent from AsyncTask, therefore, they are completely asynchronous. The class will provide abstract methods that derived classes must override and provide definitions for.
1. getUrl () - Well-formatted request URL 2. getHttpMethod () - one of the HTTP methods from GET, POST, PUT, DELETE, PATCH
3. getRequestParams () - Request parameters (headers), if any.
4. getPostParams () - Message parameters, if any.
5. parseResponse (String) - derived classes should give a definition of this method to analyze the received response.
6. notifyError (int) - derived classes must define this method to handle the error that can be received during communication.

 package com.example.sample; import java.util.ArrayList; import org.apache.http.NameValuePair; import android.os.AsyncTask; /** * This class is an abstract base class for all web services. */ public abstract class BaseService { protected abstract String getUrl(); protected abstract HttpMethods getHttpMethod(); protected abstract ArrayList< NameValuePair > getRequestParams(); protected abstract ArrayList< NameValuePair > getPostParams(); protected abstract void parseResponse( String response ); protected abstract void notifyError( int errorCode ); public void send() { SendRequestTask sendRequestTask = new SendRequestTask( ); sendRequestTask.execute( ); } private class SendRequestTask extends AsyncTask< Void, Void, Integer > { @Override protected Integer doInBackground( Void... params ) { try { String url = getUrl( ); HttpMethods method = getHttpMethod( ); ArrayList< NameValuePair > httpParams = getRequestParams( ); ArrayList< NameValuePair > postParams = getPostParams( ); HttpCommunication httpCommunication = new HttpCommunication( ); String response = httpCommunication.makeHttpRequest( url, method, httpParams, postParams ); parseResponse( response ); } catch ( Exception ex ) { ex.printStackTrace( ); notifyError( CommunicationError.ERROR_COMMUNICATION ); } return 0; } } } 

Here is the code for an example of the webservice class, which is derived from the above class;

 package com.example.sample; import java.util.ArrayList; import org.apache.http.NameValuePair; import org.apache.http.message.BasicNameValuePair; /** * This is a web service class to login. */ public class SignIn extends BaseService { private final String _emailId; private final String _password; private final String _signinUrl = "http://www.example.com/login.php"; public SignIn( String userName, String password ) { _emailId = userName; _password = null; } @Override protected String getUrl() { return _signinUrl; } @Override protected ArrayList< NameValuePair > getRequestParams() { ArrayList< NameValuePair > params = new ArrayList< NameValuePair >( ); params.add( new BasicNameValuePair( "header1", "header1" ) ); params.add( new BasicNameValuePair( "header2", "header2" ) ); return params; } @Override protected ArrayList< NameValuePair > getPostParams() { ArrayList< NameValuePair > params = new ArrayList< NameValuePair >( ); params.add( new BasicNameValuePair( "email", _emailId ) ); params.add( new BasicNameValuePair( "password", _password ) ); return params; } @Override protected HttpMethods getHttpMethod() { return HttpMethods.POST; } @Override protected void parseResponse( String response ) { // Parse the response here } @Override protected void notifyError( int errorCode ) { // Notify error to application } } 

Here's how you can use the SignIn web service;

 SignIn signIn = new SignIn(" [e-mail] ", "abc123"); signIn.send(); 

Modify your HttpCommunication class as follows.

 package com.example.sample; import java.io.BufferedReader; import java.io.InputStream; import java.io.InputStreamReader; import java.io.OutputStream; import java.net.HttpURLConnection; import java.net.URL; import java.util.ArrayList; import org.apache.http.NameValuePair; public class HttpCommunication { private final int CONNECTION_TIMEOUT = 10 * 1000; /** * Default Constructor */ public HttpCommunication() { } public String makeHttpRequest( String strUrl, HttpMethods method, ArrayList< NameValuePair > requestParams, ArrayList< NameValuePair > postData ) throws Exception { HttpURLConnection connection = null; InputStream inputStream = null; URL url = null; String response = null; try { url = new URL( strUrl ); connection = (HttpURLConnection) url.openConnection( ); connection.setConnectTimeout( CONNECTION_TIMEOUT ); connection.setReadTimeout( CONNECTION_TIMEOUT ); if ( requestParams != null && requestParams.size( ) > 0 ) { for ( NameValuePair pair : requestParams ) { connection.setRequestProperty( pair.getName( ), pair.getValue( ) ); } } connection.setDoInput( true ); connection.connect( ); if ( method == HttpMethods.POST ) { OutputStream os = connection.getOutputStream( ); // Convert post data to string and then write it to outputstream. String postDataStr = "test"; os.write( postDataStr.getBytes( ) ); os.close( ); } inputStream = connection.getInputStream( ); if ( inputStream != null ) { BufferedReader reader = new BufferedReader( new InputStreamReader( inputStream, "UTF-8" ) ); StringBuilder sb = new StringBuilder( ); String line = null; while ( ( line = reader.readLine( ) ) != null ) { sb.append( line + "\n" ); } response = sb.toString( ); inputStream.close( ); } connection.disconnect( ); } catch ( Exception e ) { if ( connection != null ) { connection.disconnect( ); } } return response; } }