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MV103 Android HttpClient Post Method and Remote JSON Data
0) Starting Up
Continue from the previous tutorial or download startup files here.
1) Add a new activity.
Right-click the project name, select New/Other...
Select Android Activity.
Select Blank Activity.
Give a name “VolunteerActivity” and click Finish.
Check Project Navigator.
2) Edit Resources for New Activity (Volunteer)
2.1) Add Image
Save the above image as res/drawable/person_small.png
2.2) Layout
res/layout/activity_volunteer.xml
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".SettingsActivity" >
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="@drawable/person_small"
android:layout_marginTop="20dp"
android:layout_gravity="center_horizontal"
/>
<EditText
android:id="@+id/etx_name"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="10dp"
android:hint="Name" />
<EditText
android:id="@+id/etx_email"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="10dp"
android:hint="Email" />
<Button
android:id="@+id/btn_register"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="10dp"
android:text="Register"
android:background="#e6e6e6" />
</LinearLayout>
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OUTCOME.
3) Edit Main Controller
3.1) Start Volunteer Activity
MainActivity.java
package com.example.myvolunteers102;
import java.util.ArrayList;
import java.util.HashMap;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.os.AsyncTask;
import android.os.Bundle;
import android.app.Activity;
import android.app.ProgressDialog;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.Toast;
public class MainActivity extends Activity {
// JSON Node names
private static final String TAG_PERSONS= "result";
private static final String TAG_ID = "id";
private static final String TAG_NAME = "name";
private static final String TAG_EMAIL = "email";
// persons JSONArray
JSONArray persons = null;
// Hashmap for ListView
ArrayList<HashMap<String, String>> alsPersons = new ArrayList<HashMap<String, String>>();
SimpleAdapter adpPersons;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
setViewObjects();
new GetPersons().execute();
}
private void setViewObjects() {
//bind ListView
ListView mListView = (ListView) findViewById(R.id.lvw_persons);
//set adapter
adpPersons = new SimpleAdapter(MainActivity.this, alsPersons,
R.layout.activity_main_list_item, new String[] { TAG_NAME, TAG_EMAIL,}
, new int[] { R.id.name,R.id.email}
);
//plug adapter to ListView
mListView.setAdapter(adpPersons);
//bind ImageView
ImageView imvPerson =(ImageView) findViewById(R.id.imv_person);
//attach onClickListener to ImageView
imvPerson.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
//Toast.makeText(getApplicationContext(), "Add Person", Toast.LENGTH_SHORT).show();
startActivity(new Intent(MainActivity.this, VolunteerActivity.class));
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle item selection
switch (item.getItemId()) {
case R.id.menu_settings:
//
case R.id.menu_refresh:
new GetPersons().execute();
default:
return super.onOptionsItemSelected(item);
}
}
/**
* Async task class to get json by making HTTP call
* */
private class GetPersons extends AsyncTask<Void, Void, Void> {
private ProgressDialog pDialog;
// URL to get persons JSON
private String url = "http://notarazi.esy.es/myvolunteers/api/volunteers";
@Override
protected void onPreExecute() {
super.onPreExecute();
// Showing progress dialog
pDialog = new ProgressDialog(MainActivity.this);
pDialog.setMessage("Please wait...");
pDialog.setCancelable(false);
pDialog.show();
}
@Override
protected Void doInBackground(Void... arg0) {
// Creating service handler class instance
ServiceHandler sh = new ServiceHandler();
// Making a request to url and getting response
String jsonStr = sh.makeServiceCall(url, ServiceHandler.GET);
Log.d("Response: ", "> " + jsonStr);
if (jsonStr != null) {
try {
JSONObject jsonObj = new JSONObject(jsonStr);
// Getting JSON Array node
JSONArray arrPersons = jsonObj.getJSONArray(TAG_PERSONS);
//reset personList
alsPersons.clear();
// looping through All Persons
for (int i = 0; i < arrPersons.length(); i++) {
JSONObject jobPerson = arrPersons.getJSONObject(i);
String id = jobPerson.getString(TAG_ID);
String name = jobPerson.getString(TAG_NAME);
String email = jobPerson.getString(TAG_EMAIL);
// tmp hashmap for single person
HashMap<String, String> hmpPerson = new HashMap<String, String>();
// adding each child node to HashMap key => value
hmpPerson.put(TAG_ID, id);
hmpPerson.put(TAG_NAME, name);
hmpPerson.put(TAG_EMAIL, email);
// adding person to person list
alsPersons.add(hmpPerson);
}
} catch (JSONException e) {
e.printStackTrace();
}
} else {
Log.e("ServiceHandler", "Couldn't get any data from the url");
}
return null;
}
@Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
// Dismiss the progress dialog
if (pDialog.isShowing())
pDialog.dismiss();
/**
* Updating parsed JSON data into ListView
* */
adpPersons.notifyDataSetChanged();
}
}
}
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OUTCOME.
Start.
Click the Add Volunteer button.
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Volunteer Activity Page is displayed
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3.2) Automatically refresh the Main Activity when Back Button is pressed in Volunteer Activity
Move the method call from onCreate method to onResume method.
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package com.example.myvolunteers102;
import java.util.ArrayList;
import java.util.HashMap;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.os.AsyncTask;
import android.os.Bundle;
import android.app.Activity;
import android.app.ProgressDialog;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.Toast;
public class MainActivity extends Activity {
// JSON Node names
private static final String TAG_PERSONS= "result";
private static final String TAG_ID = "id";
private static final String TAG_NAME = "name";
private static final String TAG_EMAIL = "email";
// persons JSONArray
JSONArray persons = null;
// Hashmap for ListView
ArrayList<HashMap<String, String>> alsPersons = new ArrayList<HashMap<String, String>>();
SimpleAdapter adpPersons;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
setViewObjects();
//new GetPersons().execute();
}
@Override
public void onResume() {
super.onResume(); // Always call the superclass method first
new GetPersons().execute();
}
private void setViewObjects() {
//bind ListView
ListView mListView = (ListView) findViewById(R.id.lvw_persons);
//set adapter
adpPersons = new SimpleAdapter(MainActivity.this, alsPersons,
R.layout.activity_main_list_item, new String[] { TAG_NAME, TAG_EMAIL,}
, new int[] { R.id.name,R.id.email}
);
//plug adapter to ListView
mListView.setAdapter(adpPersons);
//bind ImageView
ImageView imvPerson =(ImageView) findViewById(R.id.imv_person);
//attach onClickListener to ImageView
imvPerson.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
//Toast.makeText(getApplicationContext(), "Add Person", Toast.LENGTH_SHORT).show();
startActivity(new Intent(MainActivity.this, VolunteerActivity.class));
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle item selection
switch (item.getItemId()) {
case R.id.menu_settings:
//
case R.id.menu_refresh:
new GetPersons().execute();
default:
return super.onOptionsItemSelected(item);
}
}
/**
* Async task class to get json by making HTTP call
* */
private class GetPersons extends AsyncTask<Void, Void, Void> {
private ProgressDialog pDialog;
// URL to get persons JSON
private String url = "http://notarazi.esy.es/myvolunteers/api/volunteers";
@Override
protected void onPreExecute() {
super.onPreExecute();
// Showing progress dialog
pDialog = new ProgressDialog(MainActivity.this);
pDialog.setMessage("Please wait...");
pDialog.setCancelable(false);
pDialog.show();
}
@Override
protected Void doInBackground(Void... arg0) {
// Creating service handler class instance
ServiceHandler sh = new ServiceHandler();
// Making a request to url and getting response
String jsonStr = sh.makeServiceCall(url, ServiceHandler.GET);
Log.d("Response: ", "> " + jsonStr);
if (jsonStr != null) {
try {
JSONObject jsonObj = new JSONObject(jsonStr);
// Getting JSON Array node
JSONArray arrPersons = jsonObj.getJSONArray(TAG_PERSONS);
//reset personList
alsPersons.clear();
// looping through All Persons
for (int i = 0; i < arrPersons.length(); i++) {
JSONObject jobPerson = arrPersons.getJSONObject(i);
String id = jobPerson.getString(TAG_ID);
String name = jobPerson.getString(TAG_NAME);
String email = jobPerson.getString(TAG_EMAIL);
// tmp hashmap for single person
HashMap<String, String> hmpPerson = new HashMap<String, String>();
// adding each child node to HashMap key => value
hmpPerson.put(TAG_ID, id);
hmpPerson.put(TAG_NAME, name);
hmpPerson.put(TAG_EMAIL, email);
// adding person to person list
alsPersons.add(hmpPerson);
}
} catch (JSONException e) {
e.printStackTrace();
}
} else {
Log.e("ServiceHandler", "Couldn't get any data from the url");
}
return null;
}
@Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
// Dismiss the progress dialog
if (pDialog.isShowing())
pDialog.dismiss();
/**
* Updating parsed JSON data into ListView
* */
adpPersons.notifyDataSetChanged();
}
}
}
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OUTCOME.
Start.
Click the Add Volunteer button.
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Volunteer Activity Page is displayed
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When the Back Button is pressed in Volunteer Activity Page, the apps goes back to Main Activity and automatically refreshes the list.
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4) Edit Volunteer Activity
The activity calls the setViewObjects during the onCreate event.
When the user clicks the Register Button, the apps checks that the input is not empty and according to the valid format.
Then it prepares to register to the cloud.
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4.1) Set The View Objects
File: VolunteerActivity.java
package com.example.myvolunteers102;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class VolunteerActivity extends Activity {
EditText etxName;
EditText etxEmail;
Button btnRegister;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_volunteer);
setViewObjects();
}
private void setViewObjects() {
etxName = (EditText) findViewById(R.id.etx_name);
etxEmail = (EditText) findViewById(R.id.etx_email);
btnRegister = (Button) findViewById(R.id.btn_register);
btnRegister.setOnClickListener(new OnClickListener() {
public void onClick(View view) {
if (isValidFormData()) {
registerData();
}
}
private boolean isValidFormData() {
boolean isName = false, isEmail = false;
String emailPattern = "[a-zA-Z0-9._-]+@[a-z]+\\.+[a-z]+";
String strTestValue = "";
//get field values
strTestValue = etxName.getText().toString();
//check field values validity
if (isEmptyString(strTestValue)) {
etxName.setError("Name must not be empty");
Toast.makeText(getApplicationContext(), "Name error", Toast.LENGTH_SHORT).show();
} else {
isName = true;
}
//get field values
strTestValue = etxEmail.getText().toString();
//check field values validity
if (isEmptyString(strTestValue)) {
etxEmail.setError("Email must not be empty");
Toast.makeText(getApplicationContext(), "Email error", Toast.LENGTH_SHORT).show();
} else {
if (strTestValue.matches(emailPattern)) {
isEmail = true;
} else {
etxEmail.setError("Enter valid Email format");
Toast.makeText(getApplicationContext(), "Email error", Toast.LENGTH_SHORT).show();
}
}
return (isName && isEmail);
}
// validating empty string
public boolean isEmptyString(String text) {
return (text == null || text.trim().equals("null") || text.trim()
.length() <= 0);
}
});
}
private void registerData() {
// TODO Auto-generated method stub
Toast.makeText(getApplicationContext(), "Registering...", Toast.LENGTH_SHORT).show();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_volunteer, menu);
return true;
}
}
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Name error
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Email error
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Valid inputs accepted and the Apps is ready to register the details.
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4.2) Send Post Method Request
VolunteerActivity.java
package com.example.myvolunteers102;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.os.AsyncTask;
import android.os.Bundle;
import android.app.Activity;
import android.app.ProgressDialog;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class VolunteerActivity extends Activity {
EditText etxName;
EditText etxEmail;
Button btnRegister;
String strName="", strEmail="";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_volunteer);
setViewObjects();
}
private void setViewObjects() {
etxName = (EditText) findViewById(R.id.etx_name);
etxEmail = (EditText) findViewById(R.id.etx_email);
btnRegister = (Button) findViewById(R.id.btn_register);
btnRegister.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View view) {
if (isValidFormData()) {
strName=etxName.getText().toString();
strEmail=etxEmail.getText().toString();
registerData();
}
}
private boolean isValidFormData() {
boolean isName = false, isEmail = false;
String emailPattern = "[a-zA-Z0-9._-]+@[a-z]+\\.+[a-z]+";
String strTestValue = "";
//get field values
strTestValue = etxName.getText().toString();
//check field values validity
if (isEmptyString(strTestValue)) {
etxName.setError("Name must not be empty");
Toast.makeText(getApplicationContext(), "Name error", Toast.LENGTH_SHORT).show();
} else {
isName = true;
}
//get field values
strTestValue = etxEmail.getText().toString();
//check field values validity
if (isEmptyString(strTestValue)) {
etxEmail.setError("Email must not be empty");
Toast.makeText(getApplicationContext(), "Email error", Toast.LENGTH_SHORT).show();
} else {
if (strTestValue.matches(emailPattern)) {
isEmail = true;
} else {
etxEmail.setError("Enter valid Email format");
Toast.makeText(getApplicationContext(), "Email error", Toast.LENGTH_SHORT).show();
}
}
return (isName && isEmail);
}
// validating empty string
public boolean isEmptyString(String text) {
return (text == null || text.trim().equals("null") || text.trim()
.length() <= 0);
}
});
}
private void registerData() {
// TODO Auto-generated method stub
//Toast.makeText(getApplicationContext(), "Registering...", Toast.LENGTH_SHORT).show();
new RegisterPerson().execute();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_volunteer, menu);
return true;
}
/**
* Async task class to get json by making HTTP call
* */
private class RegisterPerson extends AsyncTask<Void, Void, Void> {
String url = "http://notarazi.esy.es/myvolunteers/api/volunteers";
List<NameValuePair> params = new ArrayList<NameValuePair>(2);
String strActionStatus="status unknown",strResult="result unknown";
ProgressDialog pDialog;
@Override
protected void onPreExecute() {
super.onPreExecute();
// Showing progress dialog
pDialog = new ProgressDialog(VolunteerActivity.this);
pDialog.setMessage("Please wait...");
pDialog.setCancelable(false);
pDialog.show();
params.add(new BasicNameValuePair("name",strName));
params.add(new BasicNameValuePair("email",strEmail));
}
@Override
protected Void doInBackground(Void... arg0) {
// Creating service handler class instance
ServiceHandler sh = new ServiceHandler();
// Making a request to url and getting response
String jsonStr = sh.makeServiceCall(url,ServiceHandler.POST,params);
Log.d("Response: ", "> " + jsonStr);
if (jsonStr != null) {
try {
JSONObject jsonObj = new JSONObject(jsonStr);
// Getting JSON Array node
strActionStatus =jsonObj.getString("actionstatus");
strResult =jsonObj.getString("result");
} catch (JSONException e) {
e.printStackTrace();
}
} else {
Log.e("ServiceHandler", "Couldn't get any data from the url");
}
return null;
}
@Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
// Dismiss the progress dialog
if (pDialog.isShowing())
pDialog.dismiss();
Toast.makeText(getApplicationContext(), strActionStatus + "\n" + strResult, Toast.LENGTH_SHORT).show();
finish();
}
}
}
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Enter a new volunteer.
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Click register.
If successful, you get a toast showing “success” and id number.
The activity automatically closes itself.
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The Main Activity refreshes the list.
The new volunteer name should be displayed at the bottom of the list.
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DOWNLOAD
REFERENCES:
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