Android Web Service Access Tutorial

In this post I'm going to illustrate how we can access web service in Android using ksoap2-android project that provides a lightweight and efficient SOAP library for the Android platform.

You can download the jar file from following link;

http://ksoap2-android.googlecode.com/svn/m2-repo/com/google/code/ksoap2-android/ksoap2-android-assembly/2.5.8/ksoap2-android-assembly-2.5.8-jar-with-dependencies.jar

Here is the sample code that illustrate SOAP web service call. I have access a live web service ConvertWeight from http://www.webserviceX.NET/ which convert weight from one unit to another. I have set "envelope.dotNet = true;" in Line 53 since I'm accessing .NET web service. You can comment that line if your web service is not .NET one.

package com.sencide;
 
import org.ksoap2.SoapEnvelope;
import org.ksoap2.serialization.PropertyInfo;
import org.ksoap2.serialization.SoapObject;
import org.ksoap2.serialization.SoapPrimitive;
import org.ksoap2.serialization.SoapSerializationEnvelope;
import org.ksoap2.transport.HttpTransportSE;
 
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;
 
public class AndroidWebService extends Activity {
  
    private final String NAMESPACE = "http://www.webserviceX.NET/";
    private final String URL = "http://www.webservicex.net/ConvertWeight.asmx";
    private final String SOAP_ACTION = "http://www.webserviceX.NET/ConvertWeight";
    private final String METHOD_NAME = "ConvertWeight";
 
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
 
        SoapObject request = new SoapObject(NAMESPACE, METHOD_NAME); 
      
        String weight = "3700";
        String fromUnit = "Grams";
        String toUnit = "Kilograms";
      
        PropertyInfo weightProp =new PropertyInfo();
        weightProp.setName("Weight");
        weightProp.setValue(weight);
        weightProp.setType(double.class);
        request.addProperty(weightProp);
         
        PropertyInfo fromProp =new PropertyInfo();
        fromProp.setName("FromUnit");
        fromProp.setValue(fromUnit);
        fromProp.setType(String.class);
        request.addProperty(fromProp);
         
        PropertyInfo toProp =new PropertyInfo();
        toProp.setName("ToUnit");
        toProp.setValue(toUnit);
        toProp.setType(String.class);
        request.addProperty(toProp);
        
        SoapSerializationEnvelope envelope = new SoapSerializationEnvelope(SoapEnvelope.VER11);
        envelope.dotNet = true;
        envelope.setOutputSoapObject(request);
        HttpTransportSE androidHttpTransport = new HttpTransportSE(URL);
 
        try {
            androidHttpTransport.call(SOAP_ACTION, envelope);
            SoapPrimitive response = (SoapPrimitive)envelope.getResponse();
            Log.i("myApp", response.toString());
    
            TextView tv = new TextView(this);
            tv.setText(weight+" "+fromUnit+" equal "+response.toString()+ " "+toUnit);
            setContentView(tv);
 
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

You have to add INTERNET permission to AndroidManifest.xml as follows;

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.sencide"
      android:versionCode="1"
      android:versionName="1.0">

    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".AndroidWebService"
                  android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

    </application>
    
    <uses-permission android:name="android.permission.INTERNET"></uses-permission>
</manifest>

You can download the source code of above project (Password:sara).

I have updated my previous code in the post Android Login Screen Using HttpClient to authenticate users from web service. There I have illustrated how you can start new activity if the login is successful.

You can download the updated source code with sample .NET web service application (Password:sara).

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Android Login Screen Using HttpClient

I have updated this code to use web service and open new screen if the login is successful in my post Android Web Service Access Tutorial.

In Android we can use HTTP POST request with org.apache.http.client.HttpClient to post data to a URL. This sample project illustrate how we can post data to a URL and get the response.

package com.sencide;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;

import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class AndroidLogin extends Activity implements OnClickListener {
 
 Button ok,back,exit;
 TextView result;
 
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        // Login button clicked
        ok = (Button)findViewById(R.id.btn_login);
        ok.setOnClickListener(this);
        
        result = (TextView)findViewById(R.id.lbl_result);
        
    }
    
    public void postLoginData() {
        // Create a new HttpClient and Post Header
        HttpClient httpclient = new DefaultHttpClient();
        
        /* login.php returns true if username and password is equal to saranga */
        HttpPost httppost = new HttpPost("http://www.sencide.com/blog/login.php");

        try {
            // Add user name and password
         EditText uname = (EditText)findViewById(R.id.txt_username);
         String username = uname.getText().toString();

         EditText pword = (EditText)findViewById(R.id.txt_password);
         String password = pword.getText().toString();
         
            List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
            nameValuePairs.add(new BasicNameValuePair("username", username));
            nameValuePairs.add(new BasicNameValuePair("password", password));
            httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));

            // Execute HTTP Post Request
            Log.w("SENCIDE", "Execute HTTP Post Request");
            HttpResponse response = httpclient.execute(httppost);
            
            String str = inputStreamToString(response.getEntity().getContent()).toString();
            Log.w("SENCIDE", str);
            
            if(str.toString().equalsIgnoreCase("true"))
            {
             Log.w("SENCIDE", "TRUE");
             result.setText("Login successful");   
            }else
            {
             Log.w("SENCIDE", "FALSE");
             result.setText(str);             
            }

        } catch (ClientProtocolException e) {
         e.printStackTrace();
        } catch (IOException e) {
         e.printStackTrace();
        }
    } 
  
    private StringBuilder inputStreamToString(InputStream is) {
     String line = "";
     StringBuilder total = new StringBuilder();
     // Wrap a BufferedReader around the InputStream
     BufferedReader rd = new BufferedReader(new InputStreamReader(is));
     // Read response until the end
     try {
      while ((line = rd.readLine()) != null) { 
        total.append(line); 
      }
     } catch (IOException e) {
      e.printStackTrace();
     }
     // Return full string
     return total;
    }

    @Override
    public void onClick(View view) {
      if(view == ok){
        postLoginData();
      }
    }

}

Following code is the content of mail.xml file that is used in the above code.

<?xml version="1.0" encoding="utf-8"?>
<AbsoluteLayout
android:layout_width="fill_parent"
android:layout_height="fill_parent"
xmlns:android="http://schemas.android.com/apk/res/android"
>
<EditText android:layout_width="150px" android:layout_height="wrap_content" android:textSize="18sp" android:id="@+id/txt_username" android:layout_y="132dip" android:layout_x="128dip"></EditText>
<EditText android:layout_width="150px" android:layout_height="wrap_content" android:textSize="18sp" android:password="true" android:id="@+id/txt_password" android:layout_x="128dip" android:layout_y="192dip"></EditText>
<Button android:layout_width="100px" android:layout_height="wrap_content" android:id="@+id/btn_login" android:layout_x="178dip" android:layout_y="252dip" android:text="Login"></Button>
<TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/lbl_username" android:text="User Name" android:layout_x="37dip" android:layout_y="150dip"></TextView>
<TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/lbl_password" android:text="Password" android:layout_y="207dip" android:layout_x="50dip"></TextView>
<TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/lbl_top" android:textSize="16sp" android:typeface="sans" android:text="Please Loggin First" android:layout_x="29dip" android:layout_y="94dip"></TextView>
<TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_y="312dip" android:layout_x="50dip" android:id="@+id/lbl_result"></TextView>
</AbsoluteLayout>

Following code is the content of AndroidManifest.xml file that is used in this project. There note that I have add the line <uses-permission android:name= "android.permission.INTERNET".

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.sencide"
      android:versionCode="1"
      android:versionName="1.0">

 <uses-permission android:name="android.permission.INTERNET" />
    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".AndroidLogin"
                  android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

    </application>
</manifest>

You can download the source code of above project (Password:sara).

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Event Handling In Android

In my previous article I discussed about how to create user interfaces in Android. Here I’m going to show you how you can add event handler to that UI. To do that, first add these two lines between package and class declaration.

To do that, first add these two lines between package and class declaration.

import android.view.View;
import android.widget.Button;

Now replace your onCreate method using following code.

import android.view.View;
import android.widget.Button;

public void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.testview);
 Button ok = (Button)findViewById(R.id.btn_testview_ok);
 ok.setOnClickListener(new View.OnClickListener() {
  public void onClick(View v){
   moveToMain();
  }
 });
}
private void moveToMain() {
 // TODO Auto-generated method stub
 setContentView(R.layout.main);
}

In the above code "btn_testview_ok" is the id of the "Ok" button in previous article. When you click that button, the moveToMain(); method will be called and content view will changed as "main.xml". I will discuss more about this topic in my next posts.

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Android User Interface Design

In one of my previous post I discussed about Creating Android Databases. In this tutorial I’ll discuss simple way to create Android UI using Eclipse and DroidDraw tool which support drag-and-drop of widgets like buttons, labels, text boxes, etc.

Displaying the user interface is done by Activity, the fundamental unit of an Android application. The setContentView() method of the Activity class load the XML UI located in the res/layout folder in the onCreate() event.

An Activity has Views and ViewGroups. Here View is a widget and collection of one or more View can be considered as ViewGroup. ViewGroup plays a major role by providing us layout to arrange the appearance and sequence of views. Well, let’s built our first User Interface in Android.

1. First create simple Android project.

2. Then using DroidDrow design your interface (show steps) and click "Generate" button at the top left corner.

First open DroidDrow and select AbsoluteLayout because using that layout you can easily place widgets as you want.

Then drag–and-drop widgets you want to the design surface.

You can change properties of your widgets using "Properties" tab. There if you want to change the Id, change the things after "@+id/".

Finally click "Generate" button to get the XML code to the "output" textbox.

3. Now add new XML file to "layout" folder as follows. There I’ll give the file name as "testview.xml". Don’t use capital letters for the name.

4. Then click on "testview.xml" tab and replace existing code by generated code from the DroidDrow tool.

5. Now replace the "setContentView(R.layout.main);" using "setContentView(R.layout.testview);". Now your "onCreate" method should appear as follows.

public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.testview);
}

Finally save all and run the project to see your interface in Android.

If you are interested please refer Event Handling in Android to learn how to handle events for these widgets.

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Create Android Database

This sample code illustrates how we can use Android SQLite Database to store data in Android.

Following example will give output as Saranga/22 since I have created a text view and set the out put to it. If you want to add your own fields, first drop the existing table using given source code.

import android.app.Activity;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;
public class DBTest extends Activity {
 /** Called when the activity is first created. */
 @Override
 public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);

  SQLiteDatabase myDB= null;
  String TableName = "myTable";

  String Data="";

  /* Create a Database. */
  try {
   myDB = this.openOrCreateDatabase("DatabaseName", MODE_PRIVATE, null);

   /* Create a Table in the Database. */
   myDB.execSQL("CREATE TABLE IF NOT EXISTS "
     + TableName
     + " (Field1 VARCHAR, Field2 INT(3));");

   /* Insert data to a Table*/
   myDB.execSQL("INSERT INTO "
     + TableName
     + " (Field1, Field2)"
     + " VALUES ('Saranga', 22);");

   /*retrieve data from database */
   Cursor c = myDB.rawQuery("SELECT * FROM " + TableName , null);

   int Column1 = c.getColumnIndex("Field1");
   int Column2 = c.getColumnIndex("Field2");

   // Check if our result was valid.
   c.moveToFirst();
   if (c != null) {
    // Loop through all Results
    do {
     String Name = c.getString(Column1);
     int Age = c.getInt(Column2);
     Data =Data +Name+"/"+Age+"\n";
    }while(c.moveToNext());
   }
   TextView tv = new TextView(this);
   tv.setText(Data);
   setContentView(tv);
  }
  catch(Exception e) {
   Log.e("Error", "Error", e);
  } finally {
   if (myDB != null)
    myDB.close();
  }
 }
}

You can download source code here.

Password: sara

Tested with Android 2.3.3 Platform SDK.

If you are interested please refer Android User Interface Design to learn simple way to Designing interfaces.

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VanCafe, My Android Project

Using Andriod we have built a solution for delivery van based Cafeteria. The overall process that targeted here is as follows. There is a main center cafe and there are delivery vans which would be assigned to different places. They sell goods to customers and the customers can order things via the mobile network using their smart phones. The vans are delivering the goods to the appropriate location.

Main focus on this system is towards a cafeteria which possesses number of delivery vans which do selling within different service areas and in the same time provides the customer with the facilities to make orders through their smart phones.

The Cafeteria has multiple delivery vans to sell and deliver food items to customers within the service area. Cafe Manager defines the service area which is fixed for a longer period of time. Vans are filled every morning and are allowed to come to the Cafeteria at any time to do refilling. Vans are expected to stay within their service area and an “Area Boundary Notification” shall be generated when the van crosses the defined boundary.

Customers can use the mobile device to view available items, view promotions and to order items. The customer location shall be automatically sent with the order. When an order is placed it shall be assigned to the van closest to the customer, depending on the stock availability. In addition to the order delivery vans can do direct sales on the road. Vans can also take orders from customers on the road.

The main features of this system is the usage of the facilities in the mobile environment. In spite of that, consumer friendly applications would be implemented to help the customer and the business (i.e. delivery van or the manager) with their day-to-day activities.

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