The key to using POST with HttpURLConnection is to write the POST parameters to an output stream:
wr = new DataOutputStream(conn.getOutputStream());
wr.writeBytes(paramsString);
Here is a full working example of how you could implement the login functionality with HttpURLConnection.
First, the JSONParser class, which makes the network request and returns a JSON response:
import android.util.Log;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;
import java.util.HashMap;
public class JSONParser {
String charset = "UTF-8";
HttpURLConnection conn;
DataOutputStream wr;
StringBuilder result;
URL urlObj;
JSONObject jObj = null;
StringBuilder sbParams;
String paramsString;
public JSONObject makeHttpRequest(String url, String method,
HashMap<String, String> params) {
sbParams = new StringBuilder();
int i = 0;
for (String key : params.keySet()) {
try {
if (i != 0){
sbParams.append("&");
}
sbParams.append(key).append("=")
.append(URLEncoder.encode(params.get(key), charset));
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
i++;
}
if (method.equals("POST")) {
// request method is POST
try {
urlObj = new URL(url);
conn = (HttpURLConnection) urlObj.openConnection();
conn.setDoOutput(true);
conn.setRequestMethod("POST");
conn.setRequestProperty("Accept-Charset", charset);
conn.setReadTimeout(10000);
conn.setConnectTimeout(15000);
conn.connect();
paramsString = sbParams.toString();
wr = new DataOutputStream(conn.getOutputStream());
wr.writeBytes(paramsString);
wr.flush();
wr.close();
} catch (IOException e) {
e.printStackTrace();
}
}
else if(method.equals("GET")){
// request method is GET
if (sbParams.length() != 0) {
url += "?" + sbParams.toString();
}
try {
urlObj = new URL(url);
conn = (HttpURLConnection) urlObj.openConnection();
conn.setDoOutput(false);
conn.setRequestMethod("GET");
conn.setRequestProperty("Accept-Charset", charset);
conn.setConnectTimeout(15000);
conn.connect();
} catch (IOException e) {
e.printStackTrace();
}
}
try {
//Receive the response from the server
InputStream in = new BufferedInputStream(conn.getInputStream());
BufferedReader reader = new BufferedReader(new InputStreamReader(in));
result = new StringBuilder();
String line;
while ((line = reader.readLine()) != null) {
result.append(line);
}
Log.d("JSON Parser", "result: " + result.toString());
} catch (IOException e) {
e.printStackTrace();
}
conn.disconnect();
// try parse the string to a JSON object
try {
jObj = new JSONObject(result.toString());
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
// return JSON Object
return jObj;
}
}
Here is an example of how you would initiate the login from an AsyncTask in your Activity:
class PostAsync extends AsyncTask<String, String, JSONObject> {
JSONParser jsonParser = new JSONParser();
private ProgressDialog pDialog;
private static final String LOGIN_URL = "http://www.example.com/testPost.php";
private static final String TAG_SUCCESS = "success";
private static final String TAG_MESSAGE = "message";
@Override
protected void onPreExecute() {
pDialog = new ProgressDialog(MainActivity.this);
pDialog.setMessage("Attempting login...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
}
@Override
protected JSONObject doInBackground(String... args) {
try {
HashMap<String, String> params = new HashMap<>();
params.put("name", args[0]);
params.put("password", args[1]);
Log.d("request", "starting");
JSONObject json = jsonParser.makeHttpRequest(
LOGIN_URL, "POST", params);
if (json != null) {
Log.d("JSON result", json.toString());
return json;
}
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
protected void onPostExecute(JSONObject json) {
int success = 0;
String message = "";
if (pDialog != null && pDialog.isShowing()) {
pDialog.dismiss();
}
if (json != null) {
Toast.makeText(MainActivity.this, json.toString(),
Toast.LENGTH_LONG).show();
try {
success = json.getInt(TAG_SUCCESS);
message = json.getString(TAG_MESSAGE);
} catch (JSONException e) {
e.printStackTrace();
}
}
if (success == 1) {
Log.d("Success!", message);
}else{
Log.d("Failure", message);
}
}
}
When you want to login the user, execute the AsyncTask, and pass in the username and password:
String username = "testuser"; //get this from user input
String password = "testpass"; //get this from user input
new PostAsync().execute(username, password);
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