Java Archives - Dumbsum Dumbsum

Today I am going to talk about how to create a simple phone application using the popular Twilio API. If you don’t know what Twilio is all about then I recommend you go through their “What is Cloud Communications” section.

Twilio

When I was working for Infofree I was given a task to come up with a basic SMS and Voice Authentication system using any available services out there. My two options back then was either Corvisa (now Shoretel) or Twilio. I tried to work with Corvisa and their API but, it lacked a lot of features that Twilio has. So ultimately, I decided to build the feature using Twilio. Sadly, because of economic reasons for my company my code was never live. But, in my free time I went further and used Twilio’s service to test different features.

In this tutorial I will show you how to setup basic twilio service using JAVA.

These are some of the things you will need in order for yor app to work.

Twilio Account SID TWILIO_ACCOUNT_SID
Twilio Authentication Token TWILIO_AUTH_TOKEN
Twilio Number TWILIO_NUMBER
Twilio Application SID (Optional)
Twilio Agent Number (Optional)

Get API Key

Go to twilio and click on the “Get a Free API Key button”.

Get a Free API Key – Twilio

Go through the general registration process (should be easy). You need to verify using your phone number.

After you are done, go to Home-> Settings-> General

You should see your TWILIO_ACCOUNT_SID and TWILIO_AUTH_TOKEN

Get Phone Number

If you plan to use your number then you do not need to get TWILIO_NUMBER else click here and get a phone number. For trial purposes you can only use verified phone numbers.

Get a new phone number

You should see this number in your Manage Numbers section.

Things you’ll need for JAVA

If you use maven, you need to add this dependency in your pom.xml file:

<dependency>
  <groupId>com.twilio.sdk</groupId>
  <artifactId>twilio</artifactId>
  <version>(7.0,7.9)</version>
</dependency>

If you don’t use maven, use this jar file instead: twilio-7.x.x-with-dependencies.jar

Here I will be using a properties file (db.properties) to store all my API credentials

#mysql DB properties
DB_DRIVER_CLASS=com.mysql.jdbc.Driver
DB_URL=jdbc:mysql://localhost:3306/test
DB_USERNAME=username
DB_PASSWORD=password

TWILIO_ACCOUNT_SID=ACed9da74780242eded3a2fb674a*****
TWILIO_AUTH_TOKEN=fac36407eb1bf66f207d2763671*****
TWILIO_NUMBER=+14023789330
TWILIO_APPLICATION_SID=

Once you have everything setup, we can use Twilio’s API library to do various tasks.

Go ahead and download this sample code to play around some of the features.

I also created a Phone Verification system where you could verify phone using either a SMS or a Voice Call. But because it was part of my company project, I cannot share the code with you. But here is the screenshot of how it looks like.

Phone Verification using Twilio

Following are some of the examples:

Send SMS

SendSMS

package com.twilioAPI;

import com.twilio.sdk.resource.instance.Account;
import com.twilioAPI.exceptions.UndefinedEnvironmentVariableException;
import com.twilioAPI.lib.AppSetup;
import com.twilio.sdk.TwilioRestClient;
import com.twilio.sdk.TwilioRestException;
import com.twilio.sdk.resource.factory.MessageFactory;
import com.twilio.sdk.resource.instance.Message;
import java.util.ArrayList;
import java.util.List;
import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class sendSMS
 */
@WebServlet("/sendSMS")
public class SendSMS extends HttpServlet {
	private static final long serialVersionUID = 1L;
	private AppSetup appsetup;
    /**
     * @see HttpServlet#HttpServlet()
     */
    public SendSMS() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		response.getWriter().append("Served at: ").append(request.getContextPath());
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request, response);
		this.appsetup = new AppSetup();
		try {
			String accountSid = this.appsetup.getAccountSid();
			String authToken = this.appsetup.getAuthToken();
			String fromNumber = this.appsetup.getTwilioNumber();
			TwilioRestClient client = new TwilioRestClient(accountSid, authToken);
			String pNumber = request.getParameter("phoneSMS");
			String pMessage = request.getParameter("testSMS");
			Account account = client.getAccount();
			MessageFactory messageFactory = account.getMessageFactory();
	        List<NameValuePair> params = new ArrayList<NameValuePair>();
	        params.add(new BasicNameValuePair("To", pNumber)); // Replace with a valid phone number for your account.
	        params.add(new BasicNameValuePair("From", fromNumber)); // Replace with a valid phone number for your account.
	        params.add(new BasicNameValuePair("Body", pMessage));
	        Message sms = messageFactory.create(params);
	        System.out.println("Sending SMS...: To:" + pNumber + "From:"+ fromNumber+ "and Message:" +pMessage);
		} catch (UndefinedEnvironmentVariableException | TwilioRestException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
        
		
		
		
		
	}

}

Click-to-Call

package com.twilioAPI;

import com.twilioAPI.exceptions.UndefinedEnvironmentVariableException;
import com.twilioAPI.lib.AppSetup;
import com.twilio.sdk.TwilioRestClient;
import com.twilio.sdk.TwilioRestException;
import org.json.simple.JSONObject;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.HashMap;
import java.util.Map;
/**
 * Servlet implementation class Call
 */
@WebServlet("/Call")
public class Call extends HttpServlet {
	private static final long serialVersionUID = 1L;
	 AppSetup appSetup;
	  TwilioRestClient client;

	  public Call() {}

	  public Call(AppSetup appSetup, TwilioRestClient client) {
	    this.appSetup = appSetup;
	    this.client = client;
	  }
	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		response.getWriter().append("Served at: ").append(request.getContextPath());
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
	    String phoneNumber = request.getParameter("phone");
	    if(phoneNumber==null||phoneNumber==""){
	    	phoneNumber = request.getParameter("phoneNumber");
	    }
	    boolean record = request.getParameter( "record" ) != null;
	    String CallRecord = "false";
	    if (record == true){
	    	CallRecord = "true";
	    }
	    request.getServletContext().setAttribute("record", CallRecord);
	    
	    if (phoneNumber != null) {
	      if (this.appSetup == null || this.client == null) {
	        appSetup = new AppSetup();
	        client = null;
	        try {
	          client = new TwilioRestClient(appSetup.getAccountSid(), appSetup.getAuthToken());
	        } catch (UndefinedEnvironmentVariableException e) {
	          response.getOutputStream().write(getJSONResponse(e.getMessage()).getBytes());
	          return;
	        }
	      }

	      Map<String, String> params = new HashMap<>();
	      String twilioNumber;
	      try {
	        twilioNumber = appSetup.getTwilioNumber();
	      } catch (UndefinedEnvironmentVariableException e) {
	        response.getOutputStream().write(getJSONResponse(e.getMessage()).getBytes());
	        return;
	      }

	      // Full path to the end point that will respond with the call TwiML
	      //String path = request.getRequestURL().toString().replace(request.getRequestURI(), "") + "/CorvisaAPI/connect?record="+CallRecord;
	      String path = request.getRequestURL().toString().replace(request.getRequestURI(), "") + "/CorvisaAPI/connect";
	      params.put("From", twilioNumber);
	      params.put("To", phoneNumber);
	      params.put("Url", path);
	      try {
	        client.getAccount().getCallFactory().create(params);
	      } catch (TwilioRestException e) {
	        String message = "Twilio rest client error: " + e.getErrorMessage() +
	            "\nRemember not to use localhost to access this app, use your ngrok URL";
	        response.getOutputStream().write(getJSONResponse(message).getBytes());
	        return;
	      }
	      response.getOutputStream().write(getJSONResponse("Phone call incoming!").getBytes());
	    } else {
	      response.getOutputStream()
	          .write(getJSONResponse("The phone number field can't be empty").getBytes());
	    }
	}
	private String getJSONResponse(String message) {
	    JSONObject obj = new JSONObject();
	    obj.put("message", message);
	    obj.put("status", "ok");

	    return obj.toJSONString();
	  }

}

Web Phone

WebPhone

package com.twilioAPI;

import com.twilioAPI.exceptions.UndefinedEnvironmentVariableException;
import com.twilioAPI.lib.AppSetup;
import com.twilio.sdk.TwilioRestClient;
import com.twilio.sdk.TwilioRestException;
import org.json.simple.JSONObject;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.HashMap;
import java.util.Map;
/**
 * Servlet implementation class Call
 */
@WebServlet("/Call")
public class Call extends HttpServlet {
	private static final long serialVersionUID = 1L;
	 AppSetup appSetup;
	  TwilioRestClient client;

	  public Call() {}

	  public Call(AppSetup appSetup, TwilioRestClient client) {
	    this.appSetup = appSetup;
	    this.client = client;
	  }
	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		response.getWriter().append("Served at: ").append(request.getContextPath());
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
	    String phoneNumber = request.getParameter("phone");
	    if(phoneNumber==null||phoneNumber==""){
	    	phoneNumber = request.getParameter("phoneNumber");
	    }
	    boolean record = request.getParameter( "record" ) != null;
	    String CallRecord = "false";
	    if (record == true){
	    	CallRecord = "true";
	    }
	    request.getServletContext().setAttribute("record", CallRecord);
	    
	    if (phoneNumber != null) {
	      if (this.appSetup == null || this.client == null) {
	        appSetup = new AppSetup();
	        client = null;
	        try {
	          client = new TwilioRestClient(appSetup.getAccountSid(), appSetup.getAuthToken());
	        } catch (UndefinedEnvironmentVariableException e) {
	          response.getOutputStream().write(getJSONResponse(e.getMessage()).getBytes());
	          return;
	        }
	      }

	      Map<String, String> params = new HashMap<>();
	      String twilioNumber;
	      try {
	        twilioNumber = appSetup.getTwilioNumber();
	      } catch (UndefinedEnvironmentVariableException e) {
	        response.getOutputStream().write(getJSONResponse(e.getMessage()).getBytes());
	        return;
	      }

	      // Full path to the end point that will respond with the call TwiML
	      //String path = request.getRequestURL().toString().replace(request.getRequestURI(), "") + "/CorvisaAPI/connect?record="+CallRecord;
	      String path = request.getRequestURL().toString().replace(request.getRequestURI(), "") + "/CorvisaAPI/connect";
	      params.put("From", twilioNumber);
	      params.put("To", phoneNumber);
	      params.put("Url", path);
	      try {
	        client.getAccount().getCallFactory().create(params);
	      } catch (TwilioRestException e) {
	        String message = "Twilio rest client error: " + e.getErrorMessage() +
	            "\nRemember not to use localhost to access this app, use your ngrok URL";
	        response.getOutputStream().write(getJSONResponse(message).getBytes());
	        return;
	      }
	      response.getOutputStream().write(getJSONResponse("Phone call incoming!").getBytes());
	    } else {
	      response.getOutputStream()
	          .write(getJSONResponse("The phone number field can't be empty").getBytes());
	    }
	}
	private String getJSONResponse(String message) {
	    JSONObject obj = new JSONObject();
	    obj.put("message", message);
	    obj.put("status", "ok");

	    return obj.toJSONString();
	  }

}

Other uses are Phone Verification system, Conference Call, etc.

Today, I am going to talk about something simple and useful in programming. For people who are professional programmers this might seem relatively easy but for someone who is trying to learn PHP or Java having a knowlege of how arrays work might be really useful. Especially when you have a large set of data and you need to display it in multiple columns.

So let’s talk about how to use PHP’s and Java’s inbuilt array funtion to slice a large array into smaller parts. For this tutorial, I am assuming you have some knowledge of how PHP and Java works. If not, there are hundreds of websites and books available to get basic understanding.

Scenario: I was given a task to list all the 52 US states in a page so that only the ones that are flagged as active in a table inside database is shown on the page. I had to show this in 3 columns.

#	State Name	Active Flag
1	Alabama	1
2	Alaska	1
3	Arizona	0
4	Arkansas	1
5	…	1

Result: The result should look something like this.

Alabama
Alaska
Arkansas
California
…

Kentucky
Louisiana
Maine
Maryland
…

North Dakota
Ohio
Oklahoma
Oregon
…

Now, the question might seem relatively easy. And we don’t necessarily need PHP or JAVA to solve this. We could also use something on client side like JavaScript. But, I’ll show how it’s done on the server side.

Query Database for Results:

We can get the list of active states from the database as follows:

SELECT * FROM states where active_flag = 1 order by state_id asc;

For PHP you get the data as follows:

<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";

// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
} 

$sql = "SELECT * FROM states WHERE active_flag = 1 ORDER BY state_id ASC;";
$result = $conn->query($sql);
$states = array();
if ($result->num_rows > 0) {
    // output data of each row
    while($row = $result->fetch_assoc()) {
        $states[] = $row;
    }
} else {
    echo "No Results Found";
}

$conn->close();
?>

The above code connects to the database and quries the result and puts it inside the $states[] array.

In Java, you can do the same utilizing Java’s inbuilt database connection library:

Connection conn = null;
CallableStatement stmt = null;
ResultSet result = null;
ArrayList<String> states = new ArrayList<String>();
		
try {
        conn = getConnection();
	stmt = conn.prepareCall("SELECT * FROM states WHERE active_flag = 1 ORDER BY state_id ASC;");

	result = stmt.executeQuery();

	while (result.next()) {

		String state_name = result.getString("state_name");
		states.add(state_name);
	}

} catch (SQLException e) {
	LOG.log(Level.SEVERE, e.getMessage(), e);

} finally {
	result.close();
	stmt.close();
	conn.close();
}

The above code puts the result inside states array. Here, getConnection() actually connects to the database. You can google and read about how to connect to database in Java to understand it much better. But, the idea is simple. We utilize Java’s SQL library to automatically connect to the database. You just define all the required connection settings in a properties file (below is just an example).

protected static Connection getConnection() throws SQLException {
     return DriverManager.getConnection("**** Database Name ****");
}

Now that we have our results in an array. Let’s see how we can split the array into three sub arrays.

Array Count or Length

Before we do the actual splitting, we need to know the count of the total states in the array so that we can split the array evenly across the three arrays.

To do this, in PHP we use the inbuilt function count($array).

$states_count=count($states);

In Java we simply we utilize array.length property of an array.

int states_count = states.length;

Divisible by 3

Now that we know the array length, we need to know how to evenly distribute the states into three sets of list. The logic here is to make the length (or count) of the list divisible by 3 so that we can evenly distribute the states among three sets.

The concept of modulus is very helpful here. The modulo operation (or simply modulus) finds the remainder after division of one number by another. To check if a number is divisible by 3 or not we do the following:

First, we check to see if the number is even or odd.
If even, we add +1 and do the modulo operand on the length. This is done as number % divisor. If this outputs a number, besides 0, then we know the number is not divisible by divisor. Here we know length or count is even as $states_count % 2 gives us 0. If so, we loop and keep on adding 1 ($states_count++;) until we get a number that is divisible by 3 (loop until $states_count % 3 is not 0).
If odd, we test and see if this odd number is divisible by 3 ($states_count % 3 == 0). If the number is not divisible by 3 we keep adding 1 until we get a number that is divisible by 3.

In PHP

if($states_count % 2 == 0){
   do {
      $states_count++;
   }while($states_count % 3 != 0);
}else{
   if($states_count % 3 == 0){
      //do nothing
   }else{
      do {
	 $states_count++;
      }while($states_count % 3 != 0);
   }
}

In Java

if(states_count % 2 == 0){
   do {
      states_count++;
   }while(states_count % 3 != 0);
}else{
   if(states_count % 3 == 0){
      //do nothing
   }else{
      do {
	 states_count++;
      }while(states_count % 3 != 0);
   }
}

Split Array in 3

Now that we have an array length that is divisible by 3, we can do the following to split the array.

In PHP we will use array_slice() method to slice into three parts. The syntax for array_slice() is

array_slice(array, starting index, length);

$states_first = array_slice($states, 0, $states_count/3);
$states_second = array_slice($states, $states_count/3, $states_count/3);
$states_third = array_slice($states, ($states_count/3)*2, $states_count/3);

In Java we will use Arrays.copyOfRange method to make a copy of or split an array. The syntax for copyOfRange() is

int[] newArray = Arrays.copyOfRange(array, starting index, ending index);

ArrayList<String> states_first = new ArrayList<String>();
ArrayList<String> states_second = new ArrayList<String>();
ArrayList<String> states_third = new ArrayList<String>();

states_first = Arrays.copyOfRange(states, 0, states_count/3);
states_second = Arrays.copyOfRange(states, states_count/3, (states_count/3)*2);
states_third = Arrays.copyOfRange(states, (states_count/3)*2, states_count);

And there you go! That’s how you split an array. You can split into any number using the same concept. Let me know what you think or if you have an even better way.

Getting started with Twilio Phone Services